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Glass Materials in Nuclear Technology for Gamma Ray and Neutron Radiation Shielding: a Review

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Abstract

The review deals the investigation of glass doped with elements exhibiting high cross section for shielding against the neutrons and gamma ray radiation. The attenuation ability of pure gamma ray, fast neutrons, slow neutrons, and total gamma rays is reviewed and discussed. A short literature review on the glass materials for nuclear radiation shielding is also given.
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Nonlinear Optics, Quantum Optics, Vol. 53, pp. 107–159
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107
Glass Materials in Nuclear Technology for
Gamma Ray and Neutron Radiation Shielding:
a Review
Aly SAeed1, R. M. el ShAzly1, y. h. elbAShAR2,*, A. M. Abou el-AzM1,
M. N. h. CoMSAN3, M. M. el-okR1 ANd W. A. kANSouh3
1Physics Department, Faculty of Science, Al-Azhar University, Cairo, Egypt
2Egypt Nanotechnology Center (EGNC), Cairo University, Giza, Egypt
3Nuclear Research Center, Egyptian Atomic Energy Authority, Egypt
Received: September 1, 2019. Accepted: March 2, 2020.
The review deals the investigation of glass doped with elements exhibit-
ing high cross section for shielding against the neutrons and gamma ray
radiation. The attenuation ability of pure gamma ray, fast neutrons, slow
neutrons, and total gamma rays is reviewed and discussed. A short litera-
ture review on the glass materials for nuclear radiation shielding is also
given.
Keywords: Glass shielding, gamma ray shielding, nuclear technology, neutron
shielding, nuclear spectroscopy
1. INTRODUCTION
Life on earth developed under avpermanent exposure to radiation, which is a
part of our daily life. So the radiation and the life are inseparable. In recent
decades of the twentieth century a huge revolution took place in the use of
nuclear technology in many different applications and the use of ionizing
radiation in various fields of industrial, agricultural, medical, and many other
areas. Thus the exposure to ionizing radiation is no longer limited to natural
sources but the artificial sources become a major part of this exposure. Expo-
Corresponding author’s e-mail: y_elbashar@yahoo.com
108 Aly SAeed et al.
sure to ionizing radiation consists mainly of two distinct components, namely,
internal and external exposure. The exposure causes deformation of the
atomic structure of the living tissue, leading to its damage. The protection
from exposure to the nuclear radiation was an important subject considered
largely in the field of nuclear physics. The general principles for radiation
protection are time, distance, and shielding. Shielding is generally preferred
due to its efficiency in intrinsically safe working conditions, whereas reliance
on distance and time of exposure involves continuous administrative control
over workers [1]. The type and amount of shielding required depends on the
type of radiation, the activity of radiation source and the dose rate that is
acceptable outside the shielding material. However, there are other factors for
the choice of shielding material such as their cost and weight. An effective
radiation shielding will cause a large energy loss in a small penetration depth
without emission of more hazardous radiation. At the same time irradiation
side effects on its physical properties should be small. A number of experi-
mental and theoretical studies were performed on radiation shielding, which
has wide, different application areas with different materials (e.g. concrete,
semi- conductor, polymer, Lipowitz alloy, colemanite, etc.) [2].
Nowadays, some of the promising materials are glassy systems in the
regard of radiation shielding because they can be transparent to visible light
and their properties can be modified by changing their composition and the
preparation technique. Several glasses were used for nuclear engineering
applications because they accomplish the double task of allowing visibility
while absorbing radiations like gamma-ray and neutrons. A good shielding
glass should exhibit a high absorption cross-section and at the same time the
irradiation effects on its mechanical, electrical and optical properties should
be small. In the last decades, many experimental and theoretical studies, deal-
ing with the investigation of the attenuation and penetration of gamma ray
and neutrons in different types of glassy shielding were carried out [3].
1.1 Literature survey
C.A. Stone et al. [1994], studied glass containing a high concentration of 6Li
and its use for the thermal neutron shielding. The glass composition was the
following: 31 mol% of 6Li2O and 69 mol% of SiO2. Studies were performed
on the second formulation that contained as much as 37 mol% of 6Li2O and
59 mol% of SiO2, with 4 mol% Al2O3 added to prevent crystallization at
such high 6Li2O concentration. The lithium silicate glasses can be formed
into variety of shapes using conventional glass fabrication techniques [4].
Kulwant Singh et al. [2002], investigated the mass attenuation coeffi-
cients of the bismuth borate glass at 356, 662, 1173, and 1332 keV photon
energies using a narrow beam transmission method. The calculated values by
(WinXCom software version 3.1) were compared with the obtained experi-
mental data. Appreciable variations were observed in these coefficients
caused by the change in the chemical composition of glasses. On the other
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 109
hand, the coefficients were then used to determine effective atomic numbers
of glass samples, which were found to be constant with bismuth concentra-
tion and energy. The obtained results have shown that the bismuth based glass
can be used as radiation shielding glass [5].
Harvinder Singh et al. [2003] determined experimentally the values of
the mass attenuation coefficients (µm), mean free path (mfp), effective atomic
numbers (Zeff) and effective electron density (Ne,eff) of xZnO.2xPbO.(1-3x)
B2O3 (where x=0.1–0.26) glasses using the photon energies of 511, 662,
1173, and 1332 keV and compared them with the theoretical data. The spe-
cific volume of glasses was derived from density measurements and studied
as a function of composition. It was pointed out that these glasses are poten-
tially interesting for application in radiation shielding [6].
Narveer Singh et al. [2004] studied the linear and mass attenuation coef-
ficients of two different glass systems: lead borate and bismuth lead borate
glasses, using narrow beam transmission method at 662 keV. The obtained
values were used to calculate the half value layer (HVL) parameters. These
parameters were also calculated theoretically for some standard radiation
shielding concretes at the same energy. The effect of replacing lead by bis-
muth was analyzed in terms of density, molar volume, and mass attenuation.
The two studied glassy systems were found to be promising as gamma-ray
shielding materials. Their radiation shielding properties were also better than
those of investigated concretes, with an added advantage of being transparent
in visible light. Their high values of mass attenuation coefficients and low
values of HVL in comparison to concretes indicated that the volume required
is less than for the concretes [7].
Kulwant Singh et al. [2005] used the transmission method to measure the
mass attenuation coefficients of the system xCaO-(0.3 -x) SrO-0.7B2O3 at
photon energies 511, 662, 1173, and 1332 keV. They used the obtained data
to calculate the effective atomic numbers, and effective electron density. The
mass attenuation coefficients, at a given photon energy, varied slowly with
composition. This was due to the almost constant electron density, and the
fact that the attenuation is determined essentially by the Compton scattering.
The results were compared with the theoretical calculation, carried out by
WinXCom computer program. The obtained data should be helpful in poten-
tial applications in gamma ray shielding, for practical applications, e.g. in
connection with the radioactive waste disposal [8].
Narveer Singh et al. [2006] investigated the PbO.BaO.B2O3 glass sys-
tem in terms of molar mass, mass attenuation coefficients and half value layer
parameters by using gamma-ray at 511, 662 and 1274 keV photon energies.
Gamma-ray attenuation coefficients of the prepared glass samples were com-
pared with the tabulations based upon the results of XCOM computer soft-
ware. Good agreement was observed between the experimental and the
theoretical data. The results had uncertainty less than 3%. The radiation
shielding properties of the glass system were compared with some standard
110 Aly SAeed et al.
radiation shielding concretes and showed that these glasses are better than
ordinary concrete in terms of the volume required for shield design, with
added advantage of being transparent in visible light [9].
Kulwant Singh et al. [2006] determined experimentally the mass attenu-
ation coefficients for lead and bismuth borate fly-ash glasses at 81, 356, 511,
662, 1173, and 1332 keV photon energies, using a narrow-beam transmission
method. The coefficients of glasses were then used to determine their interac-
tion cross sections, the photon mean free path, effective atomic numbers, and
the electron densities. Results indicated that these fly-ash glasses exhibit an
interesting potential for application in low-energy gamma ray shielding. This
was due to their large mass attenuation coefficients and low values of HVL in
comparison to concretes. These authors observed also that the bismuth glasses
have higher density and mass attenuation coefficients than lead-containing
ones. It has shown that bismuth could substitute lead to improve the radia-
tion-shielding properties of glasses. It is apparent that the fly-ash glasses can
be advantageously used as the radiation-shielding materials [10].
Sukhpal Singh et al. [2008] measured the mass attenuation coefficient of
barium–borate–fly-ash glasses for γ-ray photon energies of 356, 662, 1173
and 1332 keV using a narrow beam transmission geometry. The theoretical
values were obtained by using the ‘mixture rule’ and the ‘XCOM’ computer
software. The photon beam was highly collimated and overall scattering
acceptance angle was less than 3%. The uncertainty in results was less than
3%. The so obtained coefficients were then used to calculate values of mean
free path, effective atomic number and electron density. Good agreements
were observed between the experimental and the theoretical values. From the
obtained results it was reported that from the shielding point of view the
barium–borate–fly-ash glasses exhibit better shieldings to gamma radiation
than the standard radiation shielding concretes and the ordinary barium–
borate glasses [11].
K.J. Singh et al. [2008] determined experimentally the gamma-ray atten-
uation coefficients using a narrow beam transmission method. It was done for
the xPbO(1-x)SiO2 (x = 0.45–0.70) glass system at 662, 1173 and 1332 keV
photon energies. These values were also obtained theoretically using the
‘mixture rule’ and the ‘XCOM’ computer software. The results were then
used to calculate the half value layer parameters. Gamma-ray shielding prop-
erties of PbO–SiO2 glass samples were compared with ordinary concretes.
The molar volume, FTIR and acoustic investigations were employed to study
the structural properties of the prepared glass system. The PbO–SiO2 glasses
are potential candidates for gamma ray shielding. Lower values of HVL in
PbO– SiO2 glasses as compared to that of concrete suggest smaller size
requirements with the advantage of being transparent visible[12].
S.R. Manohara et al. [2009] calculated the effective atomic number
(Zeff), the effective electron density (Ne,eff), and the energy dependence
(ED), at photon energies from 1 keV to 1 GeV for CaO–SrO–B2O3, PbO–
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 111
B2O3, Bi2O3–B2O3, and PbO–Bi2O3–B2O3 glasses with potential applica-
tions as gamma ray shielding materials. For medium-Z glasses, Zeff is almost
constant and equal to the mean atomic number in a wide energy range, typi-
cally 0.3 < E < 4 MeV. In such cases, Compton scattering is the dominating
photon interaction mechanism. In contrast, for high-Zeff glasses there is no
energy region where Compton scattering is truly dominating. The results
were compared with concrete and other standard shielding materials and
showed an additional advantage of being transparent in visible. The single-
valued effective atomic number calculated by XMuDat is approximately
valid at low energies where photoelectric absorption is dominating. Heavy-
metal oxide glasses containing PbO and/or Bi2O3 are promising gamma ray
shielding materials due to their high effective atomic number and a strong
absorption of gamma ray. [13].
K. Kirdsiri et al. [2009] studied the mass attenuation coefficients, total
interaction cross-sections and effective atomic numbers of lead borate glass
system with different compositions at 662 keV gamma ray energy. The results
were in fair agreement with the theoretical values, calculated by the WinX-
Com program. The mass attenuation coefficients were increasing with the
increase PbO content. This is due to the increase of effective atomic number
of glass samples, which increase the probability of photoelectric absorption
in glass. However, the Compton scattering gives dominant contribution to the
total mass attenuation coefficients for the studied glass samples. The shield-
ing properties of studied glass samples are better than the ordinary concrete
shieldings and commercial window glass with added advantage of transpar-
ency in visible region. These results indicated a good potential glasses for use
as radiation shielding materials [14].
R.S. Kaundal et al. [2010] prepared glasses of the system PbO–SrO–
B2O3 with the value of molar ratio R (=PbO/B2O3) in the region 0.14R2.0
using the melt quenching technique, in order to evaluate gamma-ray shield-
ing properties. Mass attenuation coefficients have been calculated with the
XCOM computer program. The longitudinal velocities of ultrasonic waves
were measured in glass samples at room temperature using the pulse echo
technique. The results indicated that with the increase of R-value, stability of
glass network decreases. The decrease of glass network indicates the increase
in the number of boron atoms with non- bridging oxygen at the expense of
decrease of tetrahedral borate units. This feature may lead to open glass struc-
ture with lesser rigidity of the glass samples. DSC studies have been under-
taken to measure the glass transition temperature and to get an idea about the
stability of the glass network with increasing R value [15].
J. Kaewkhao et al. [2010] determined the mass attenuation coefficients
and some other shielding parameters of borate glass matrices containing with
Bi2O3 and BaO at 662 keV, and compared with PbO in the same glass struc-
ture. The theoretical values were calculated by WinXCom software and com-
pared with the experimental data. The results found that the mass attenuation
112 Aly SAeed et al.
coefficients increased with the increasing of Bi2O3, BaO and PbO concentra-
tion. Moreover the HVL of glass samples were also better than for ordinary
concretes and commercial window glass. These results reflected that the Bi-
based glass can replace Pb in radiation shielding material. In the case of Ba
compound, it may be used at appropriate energy such as X-rays or lower
energy of gamma rays [16].
P. Limkitjaroenporn et al. [2011] studied the lead sodium borate glasses
with compositions xPbO-20Na2O-(80-x)B2O3 (where x=5, 10, 15, 20, 25,
30, 35, 40, 45, 50 and 55 mol%). The samples were prepared using the melt-
quenching method and investigated with respect to their optical, physical,
structural and gamma-rays shielding properties. The densities of these glass
samples were increasing with the increase of PbO concentration. The FTIR
spectra and molar volumes indicated that PbO acts differently in this glass
structures over their compositions. Gamma-ray shielding properties, param-
eters such as mass attenuation coefficients, effective atomic number and half
value layer were increasing with the increasing PbO concentration. The
results showed a relative difference of less than 1% between experimental
and theoretical values. Moreover, the half value layers of the glass systems
were compared with some standard radiation shielding materials and they
exhibited better shielding properties than barite and ferrite concretes at 15
and 25 mol% of PbO, respectively [17].
K. Kirdsiri et al. [2011] investigated the radiation shielding and optical
properties of xBi2O3-(100-x)SiO2, xPbO-(100-x)SiO2 and xBaO-(100- x)
SiO2 glass systems (where 30 x 70 is the composition by weight%). Mass
attenuation coefficients of glasses at 662 keV were improved by increasing
the Bi2O3 and PbO content, which raised the photoelectric absorption in the
glass matrices. The results indicated that photon is strongly attenuated in
Bi2O3 and PbO containing glasses, more than in BaO containing glass. The
results from the optical absorption spectra showed an edge that was not
sharply defined; clearly indicating the amorphous nature of glass samples. It
was observed that the cutoff wavelength for Bi2O3 containing glass was lon-
ger than for PbO and BaO containing glasses [18].
H. A. Saudi et al. [2011] have prepared a glass system with chemical
formula xBi2O3–(30-x) CdO–10B2O3–20Fe2O3-40P2O5 (0 x 30)
weight % to be used as a radiation shield. The mass attenuation coefficient
and half value layer of the glass system to gamma ray were measured
experimentally and compared with those calculated using the WinXCom
program. A database of effective mass removal cross-sections for fast neu-
trons was also introduced in this work. The obtained results were correlated
with the structural characteristics of these glasses obtained from their IR
spectra. The influence of gamma and neutrons irradiation on structural
properties was also studied [19].
Natthakridta CHANTHIMA et al. [2011] investigated experimentally
and theoretically the mass attenuation coefficients and partial interaction of
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 113
xRmOn:(100-x)SiO2 glass system (where RmOn are Bi2O3, PbO and BaO,
with 30 x 70 % by weight) at the photon energy of 662 keV. The theo-
retical values of total and partial interaction were obtained by the WinX-
Com software. The glass system was prepared by the melt-quenching
method and its radiation shielding properties were measured. Mass attenu-
ation coefficients of glasses increased with the increasing Bi2O3 and PbO
content. On the contrary, there was no significant change in mass attenua-
tion coefficient when the fraction of BaO increased. These results indicated
that photons were more attenuated in Bi2O3 and PbO. The HVL and effec-
tive atomic number results indicated that Bi can replace Pb at this energy as
a gamma-ray shielding material. For Bi2O3 and BaO, HVL was better than
for the ordinary concrete and commercial windows. It meant that Bi2O3
and BaO glasses can be used to shield gamma rays. It was suggested that
Bi2O3 and BaO glass will open new possibility for lead-free radiation pro-
tecting glasses with non-toxicity [20].
J. Kaewkhao [2011] have synthesized the Bi2O3-SiO2 glass system
by using the melt-quenching method. The radiation shielding properties
of the glass samples at various levels of bismuth content were measured
at 662 keV. Comparisons were made with theoretical values calculated by
using the WinXCom. The experimental values were generally in good
agreement with the theoretical ones. Furthermore, a comparison was
made with a lead-borate glass system with the same level of the additive.
The radiation shielding properties were found to improve with increasing
Bi2O3 concentration. The different values of Compton scattering yielded
a higher mass attenuation coefficients for the bismuth-silicate than for the
bismuth-borate glass, respectively. These results reflect a potential useful-
ness of bismuth-based glasses as new materials for lead-free radiation-
shielding glasses [21].
Suparat TUSCHAROEN et al. [2011] have prepared glasses with com-
position xBaO.(80-x)B2O3.20Fly-ash (x = 45, 50, 55, 60, 65 and 70 wt.%)
using the melt-quenching method. Mass attenuation coefficients of the fabri-
cated glass system at 662 keV were determined using the narrow beam trans-
mission method. The results were consistent with theoretical calculations
done using the WinXCom software. The mass attenuation coefficient for the
given photon energy was found to vary slowly with composition but to
increase with the increasing fraction of BaO. The glass samples having 45-60
wt.% of BaO content showed the value of mean free path shorter than in the
case of ordinary hematite-serpentine, ilmentite-limonite and basalt-magnetite
concretes. The values were smaller than in the case of all conventional con-
cretes with higher than 65 wt.% content. The mean free path results showed
that the better shielding properties were achieved at higher BaO concentra-
tions. The density measurements were reported as a function of the BaO frac-
tion. The data could be useful for potential applications of fly-ash in
developing of radiation shielding glasses [22].
114 Aly SAeed et al.
P. Limkitjaroenporn et al. [2011] have determined the mass attenuation
coefficients of glass systems xPbO: 20Na2O: (80-x) B2O3 (x = 5, 10, 15, 20,
25, 30, 35, 40, 45, 50 and 55% mol) at 662 keV photon energy using the
gamma rays transmission method. The theoretical values of mass attenuation
coefficients were calculated by the WinXCom program. The coefficients
were then used to determine the effective atomic numbers of the glass sam-
ples. All shielding parameters increased with the increasing PbO concentra-
tion. [23].
Krit Won-in et al. [2011] have prepared colorless lead free glass sam-
ples from 40 wt% local quartz sand and various concentration of BaCO3
(20-40 wt%) as the main composition in order to study their radiation
shielding properties. The gamma ray attenuation characteristics were stud-
ied for the photon energy of 662 keV. Density and refractive index were
also determined. They found that changes of prepared glass compositions
can produce better material in terms of both clarity and radiation shielding
properties. The attenuation coefficients were found to increase linearly with
the increasing BaCO3 content. Both the density and refractive index were
found also to increase. The measured linear and mass attenuation coeffi-
cients of the glass sample containing 40-wt % BaCO3 were 0.234 cm-1 and
0.0726cm2g-1, respectively. The lead-free high refractive index glass, that
is one of the ecofriendly environmental materials, can be used as the gamma
radiation shielding glass [24].
S. R. Manohara et al. [2011] introduced a geometric progression fitting
formula for calculating the gamma ray exposure buildup factors for three
heavy metal oxide (HMO) glass systems: PbO-Bi2O3-B2O3, PbO-B2O3,
and Bi2O3-B2O3. Computations were done by interpolation method using
the geometric progression fitting formula and ANSI/ANS- 6.4.3 library for
the energy range from 15 keV to 15 MeV, up to penetration depths of 40 mfp
(mean free path). The buildup factors were studied as function of incident
photon energy and penetration depth. These factors for HMO glasses cannot
be found in any standard database. They are useful for practical calculations
in gamma ray shield designs. They help also to determine and control the
thickness of the used shielding material [25].
S. Kaewjaeng et al. [2012] studied the effect of BaO on optical, physical
and radiation shielding properties of SiO2-15B2O3-2Al2O3- 10CaO-
23Na2O glasses. Glasses in composition (50-x) SiO2-15B2O3- 2Al2O3-
10CaO -23Na2O-xBaO, where x = 0, 5, 10, 15 and 20 % mol were fabricated
by the melt-quenching technique. The results have shown that the density and
molar volume of glasses were found to increase with increasing BaO concen-
tration. The optical spectra were measured by UV-VIS spectrophotometer
and showed a shift to longer wavelength. Gamma-ray shielding properties at
662 keV of SiO2-B2O3-Al2O3-CaO-Na2O-BaO glasses were studied. The
experimental results showed a good agreement with the theoretical values
which calculated by WinXCom program. Moreover, the comparison of ordi-
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 115
nary concrete and commercial window in term of half value layer was dis-
cussed and showed better radiation shielding properties with the advantage of
being transparent in visible light [26].
N. Chanthima et al. [2012] calculated the mass attenuation coefficient,
effective atomic number, effective electron density and HVL of xRmOn:(1-x)
SiO2 glass system (where RmOn are Bi2O3, PbO and BaO, with 0.3 x 0.7
as fraction of weight) by theoretical approach using WinXCom program in
the energy region from 1 keV to 100 GeV. In addition, the HVL of these glass
samples was compared with some standard shielding concretes. They
observed that the value of these parameters change with energy and composi-
tion of the silicate glasses. Better shielding properties of glass samples were
obtained as compared with some standard shielding concretes. These results
indicate that these glasses can be used as radiation shielding materials [27].
Sandeep Kaur et al. [2013] evaluated the gamma ray shielding properties
of PbO-Al2O3-B2O3 and PbO-Al2O3-SiO2 glass systems in terms of mass
attenuation coefficient, half value layer, mean free path and effective atomic
number parameters. Structural information of both the glass systems has been
obtained by using density, XRD, DSC and ultrasonic measurements. Gamma
ray shielding properties of the investigated glass systems have been com-
pared with standard nuclear radiation shielding concretes. PbO-B2O3-Al2O3
and PbO-SiO2-Al2O3 glass systems can be the potential candidates for
gamma-ray shielding applications. Higher mass attenuation coefficients and
lower HVL values of the investigated glass samples for most of the composi-
tion range show that most of the prepared glass samples are better than exist-
ing concretes. They have estimated that these glasses have smaller volume
requirements than the others as gamma ray shielding materials in nuclear
reactors [28].
2. RADIATION SHIELDING MATERIALS
2.1. Introduction
Radiation refers to the whole spectra of electromagnetic waves as well as
atomic and subatomic particles that were discovered [29]. The main sources
of radiation can be categorized as given in Table 1.
Radiation can be divided into two main categories: ionizing and non-ionizing
one. Non-ionizing radiation is electromagnetic radiation with wavelength of
about 10 nm or longer, this part of electromagnetic spectra includes “Radio-wave,
Micro-wave, Infrared, Visible light and Ultraviolet”. The ionizing radiation refers
to the radiation, which can remove an electron from atoms or molecules of the
medium, it traverse. The ionizing radiation includes the rest of electromagnetic
spectra with wavelength shorter than 10 nm such as X-rays and γ-rays as well as
atomic and subatomic particles such as α-particle, β-particle, positron, proton,
neutron, heavy ions, and mesons. The ionizing radiations are commonly classi-
116 Aly SAeed et al.
fied into two principal types. The first is the directly ionizing radiations that
include radiations of energetic particles carrying an electric charge, such as beta,
alpha particles, protons, and heavy ions. Another type of ionizing radiation are
the indirectly ionizing, such as neutrons and gamma rays, which are not charged
and cause ionization by an indirect way [31].
Directly ionizing radiation interacts very strongly with shielding media,
therefore they can be easily stopped. A very thin barrier like sheet of paper
can stop alpha particles so that alpha particles are usually not hazardous out-
side the body, but they cause damage if ingested. By contrast, indirectly ion-
izing radiation may be more penetrating and the shielding required may be
quite massive and expensive, gamma rays and neutrons are very penetrating
and can pass through thick barriers [32]. Several feet of concrete or lead
would be needed to stop highly energetic gamma rays. On the other hands,
light elements such as hydrogen and paraffin are needed to moderate a fast
neutron and high capture cross section elements such as boron and cadmium
are necessary to absorb thermal neutrons (Fig 1).
For these reasons nowadays much attention has been paid for shielding
against neutrons and gamma ray because they are the highly penetrating
through matter. Any medium can stop gamma ray and neutrons is very suffi-
ciently to stop any other type of nuclear radiation [32].
FIGURE 1
Penetrating power of ionizing radiation [32].
TABLE 1
Main sources of radiation [30].
Category Source Type of radiation
Natural Radioactivity (decaying process) α, β- particles and γ-rays
Cosmic Rays Neutrons, protons, electrons, photons, etc
Artificial Nuclear Reactors Neutrons, γ-rays and residual radioactivity
Accelerators Electrons, protons, X-rays, neutrons, etc
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 117
2.2. Radiation Hazards and Principles of Protection
People are exposed to low levels of radiation every day from background
radiation and from artificial sources. Low levels of radiation do not cause any
detectable harm. Exposure to higher levels of radiation, however, can affect
the body in a number of harmful ways, and these damaging effects may not
be seen for many years, due to the increased susceptibility of the human body
to damage from ionizing radiation, the National Council on Radiation Protec-
tion and Measurement (NCRP) recommended maximum radiation dose lim-
its allowable annually (Table 2) [33-34].
The severity of the effects depends on the amount of radiation absorbed by
the body, the type of radiation, how the radiation is taken into the body
(breathed in, eaten, or absorbed through cuts in the skin), and the length of
time a person is exposed [36].
Exposure to above-normal levels of radiation can completely kill or dam-
age living tissue, it can also increase the risk of developing cancer much later
in life. On the other hand, the exposure to very large doses of radiation can
lead to the death (Table 3) [36].
With increasing use of radioactive sources human exposure to ionizing
radiation has increased and the health hazards are increased, so practical
TABLE 2
Dose limit recommendations (N.C.R.P) [35] in Sieverts (Sv).
Type of exposure group Maximum permissible absorbed
dose equivalent
Whole Body:
Prospective annual limit
Reprospective annual units
Long term accumulation to N years of age
¾Skin
¾Hands
¾Forearms
¾Other organs
¾Fertile women
50 mSv any one year
100-150 mSv, any one year
500 (N-18) mSv
150 mSv, any one year
750 mSv, any one year
300 mSv, any one year
150 mSv, any one year
5 mSv is gestation period
Public or occasionally exposed individual
¾Individual or occasional
¾Students
5 mSv, any one year
1 mSv, any one year
Population as a whole 1.750 mSv, any one year
Emergency
life saving
Whole body
Hands, forearms
less urgent
Whole body
Hands, forearms
1000 mSv
2000 mSv
250 mSv
1000 mSv, total
118 Aly SAeed et al.
methods of protection were developed. In essence, the three effective factors
of protection from ionizing radiation are [37]:
i) Distance from radiation source
Distance is a very effective protection factor and often the least expensive
way to reduce radiation exposure. As one moves away from a point source of
radiation, the amount of radiation at a given distance from the source is
inversely proportional to the square of the distance (inverse square law) [37].
I2 = I1[d1/ d2]2
I2 = intensity at a distance (d2) from a point source
I1 = intensity at distance (d1) from the same point source
Exposure time
Reducing the exposure time is a very practical method of radiation protec-
tion. Since the amount of exposure occurs as a function of its duration.
Shorter time means less absorption of radiation [37].
Dose rate × exposure time = total dose
ii) Shielding materials
Along with understanding of the characteristics and potential benefits of dif-
ferent types of radiation came awareness of their potential harm, thus from
the need for radiation protection, the radiation shielding design and analysis
born. Radiation shielding serves a number of functions, foremost among
these is reducing the radiation exposure to persons near radiation sources,
shielding used for this purpose is named biological shielding. Shields are also
used in some nuclear reactors to reduce the intensity of γ-rays incident on the
reactor vessel, which protects the vessel from excessive heating due to γ-ray
TABLE 3
Biological effects of acute dose [36].
Acute dose Probable effect
0-250 mSv No obvious injury
250-500 mSv Possible blood changes but no serious injury
500-1000 mSv Blood-cell changes, some injury, no disability
1000-2000 mSv Injury and disability certain
2000-4000mSv Injury and disability certain, death possible
4000 mSv 50 percent fatal
6000 or more mSv Probably 100 percent fatal
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 119
absorption and reduces radiation damage due to neutrons; these shields are
named thermal shields. Sometimes shields are used to protect delicate elec-
tronic apparatus that otherwise would not function properly in a radiation
shield such apparatus shields are used, for example, in some types of military
equipment [38].
2.3. Radiation shielding materials
Variety of materials can be used for radiation shielding, but to choose an
appropriate type of shielding material, the type of radiation that is being
shielded, the energy of the radiation, and the level of dose reduction are in
need to be considered. In choosing a shielding material, the first consider-
ation must be effectiveness. If dealing with external radiation protection, the
most important consideration is personnel protection. An effective shield will
cause a large energy loss in a relatively small penetration distance without
emission of more hazardous radiation. However, other factors may also influ-
ence the choice of shielding materials such as, cost, weight of the materials as
well as how much space is available for the materials. The effectiveness of the
shielding material is determined by the interactions between the incident
radiation and the atoms of the absorbing medium. The interactions, which
take place, depend mainly upon the type of radiation, the energy of the radia-
tion, and the density of the absorbing medium. Among all the types of radia-
tion, gamma ray and neutron radiation shielding materials will be discussed
in some details [39].
2.3.1. Gamma-Ray Shielding Materials
Gamma radiation is the most difficult to shield against it. Therefore pres-
ents the biggest problem in the nuclear plant. The penetrating power of the
gamma is due, in part, to the fact that it has neither charge no mass, there-
fore, it does not interact as frequently as do the other types of radiation. The
most probable of gamma interaction are those near the nucleus or interac-
tions with the electrons around the nucleus. For this reason, more gamma
interactions occur in dense materials that have many electrons [40]. The
most common form of effective gamma rays shielding materials are: lead,
steel, concrete …etc. A few details of common gamma rays shielding mate-
rials are given below.
Lead: lead is a common shielding material used for gamma radiation. The
properties of lead that make it excellent shielding materials are its density,
high atomic number, high level of stability, ease of fabrication, high degree of
flexibility in application and its availability. [41]
Concrete: concrete is widely used as a shielding for gamma rays because
it is cheap and adaptable for any construction design. Concrete often used in
the construction of large volume shields because of its low cost and most
commonly used as the outer constituent of a shield with its own activity
shielded by an inner layer of steel, lead or other materials. [42]
120 Aly SAeed et al.
Iron: It is also a common gamma-ray shielding material and is often used
in situations where the size or configuration of the shield would make its
construction from lead alone too expensive. In such circumstances, an outer
layer of steel with inner lead lining is often an effective compromise [43].
Tungsten: For small shields or collimators, tungsten is an attractive mate-
rial. It has been shown that tungsten can be effectively and economically
utilized in large-scale applications and in shielding conditions that require a
high degree of radiation attenuation in a limited thickness. It possesses supe-
rior shielding factors compared to lead while removing the accompanying
toxicity hazard and mixed waste processing costs. However, tungsten is over
thirty times more expensive than lead; therefore, it is used sparingly and is
almost never used for massive shields [44].
Depleted uranium: DU is an excellent gamma radiation-shielding mate-
rial; it can provide equivalent gamma shielding with less thickness than other
materials such as lead and stainless steel. In shipping container applications,
DU has been used to provide gamma shielding for spent fuel casks. Another
advantageous of DU is that it can provide structural strength similar to stain-
less steel, although this characteristic of DU has not yet been recognized by
regulatory agencies [45].
2.3.2. Neutron shielding materials
Shielding against neutrons is based on three successive steps
1. Slow down fast neutron by scattering.
2. Absorb the slow neutrons.
3. Absorb the secondary produced gamma rays
The effective materials in slowing down neutrons are the light elements, par-
ticularly hydrogen. Many hydrogenous materials, such as water and paraffin,
make efficient neutron shields. However, water shields have the disadvantage
of needing maintenance; also, evaporation can lead to a potentially dangerous
loss of shielding while paraffin is flammable. At higher energies (10 MeV),
the cross section for interaction with hydrogen (1 barn) is not as effective in
slowing down neutrons. If the energy of the fast neutron is sufficiently high,
inelastic scattering with nuclei can take place in which the recoil nucleus is
elevated to one of its excited states during the collision. The nucleus quickly
de-excites, emitting a gamma ray, and the neutron loses a greater fraction of
its energy than it would in an equivalent elastic collision [46]. Inelastic scat-
tering and the subsequent gamma ray play an important role in the shielding
of high-energy neutrons. Materials with good inelastic scattering properties,
such as iron, are used to offset this decrease in cross section with increased
neutron energy. Lead, which is generally used to provide shielding against
gammas, has another advantage of shielding against fast neutrons because of
its high cross section for inelastic scattering when it is uniformly distributed
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 121
throughout a hydrogenous material. These materials can cause a large change
in neutron energy after collision for high-energy neutrons but have little effect
on the neutrons at lower energy, below 0.1 MeV [46].
Thermal neutrons with energies of 0.025 eV or less are absorbed with high
effectively by thin layers of boron or cadmium. Boron is often used in the
form of boron carbide (B4C) or boron-loaded solutions. One commonly used
material is Boral, a mixture of boron carbide and aluminum, which is avail-
able in sheets of varying thickness. Cadmium has the disadvantage of emit-
ting high-energy gamma rays after neutron capture, which may necessitate
additional gamma ray shielding. Cadmium is more effective than boron for
absorbing thermal neutrons, whereas boron is more effective for absorbing
epithermal neutrons (energy range 0.1 eV to 10 eV) [46].
2.3.3. Current Neutron-Gamma Radiation Shielding Materials
An effective radiation shield consists of a combination of hydrogenous or
other low-atomic mass number materials to moderate neutrons, as well as
materials with high capture cross section for thermal neutron, and heavy ele-
ments to absorb gamma rays (Table 4).
Examples of hybrid shielding materials are polyethylene and lead, con-
crete containing scrap iron, and more exotic materials such as lithium hydride.
Shields that are more effective can sometimes be obtained by adding boron,
lithium, or lead to polyethylene [47].
2.4. Novel shielding materials
Some studies already carried out to seek for novel shielding materials with
both the neutron and gamma ray shielding ability. A number of them are
briefly presented below.
Special glasses have been developed which accomplish the double task
of allowing visibility while absorbing gamma ray and neutrons, thus pro-
TABLE 4
Material properties for gamma and neutron absorption [38].
Material
Density
(g/cm3) Advantages Disadvantages
Lead 11.350 High gamma attenuation Poor neutron absorption
Cadmium 8.642 Good neutron absorption High mass
Concrete 2.320 Inexpensive, high neutron moderation High volume
Boron 2.31 Good neutron absorption Poor gamma absorption
Carbon 2.250 good neutron moderation, Low mass Poor gamma attenuation
Water 1.0 Inexpensive, high neutron moderation Vapor unless pressurized
Lithium 0.533 low mass, High neutron absorption Poor gamma absorption
122 Aly SAeed et al.
tecting the observer. Glasses rich in heavy elements such as lead, bismuth
and barium are an excellent absorber for gamma rays, on the other hand
glasses containing boron and cadmium are used to absorb slow neutrons..
In industry, a variety of neutron-gamma shielding materials have been
developed and supplied by industry. Some examples are given here., boro-
nated rubber and other shielding rubber & polyethylene composite (e.g.,
lead-rubber & plastics composite) are produced in the Boron Rubbers India
Company. The composite neutron-gamma guard mixtures which have been
proved the attributes/properties for potential applications in management of
solid, liquid and sludge radioactive wastes, as well as mixed grout mixtures.
In some applications, given the additional need for weight reduction and
practical considerations, there is a need for multifunctional materials which
could perform structural or other roles while providing good radiation shield-
ing capability. Characterization of this neutron-gamma shielding material
and the methods to enhance strength and ductility of this integration structure
is being studied [38].
3. GLASSY MATERIALS
3.1. Introduction
Glass is an amorphous material that can be prepared by melting and quench-
ing method. The glass was used from ancient in many applications like
cups, windows, bottles etc. Nowadays the glass finds enhanced interest due
to its wide range applications such as lasers, optical recording, optical fil-
ters, smart windows and radiation shielding, and detection. These types of
application are very important in many space of modern technology [48].
3.2. Glass Definition
The glass can be define as an amorphous materials completely lacking in long
range order, periodic structure and exhibiting a region of glass transforma-tion
behavior, so that any materials organic, or inorganic, or metallic formed by any
technique, which exhibits glass transformation behavior, is a glass [48].
3.3. Volume- temperature diagram
The relation between crystal, liquid and glass can be explained by means of
V-T curve, which reflects the behavior observed for substance, which upon
cooling from a liquid state either changes into a crystal or moves into the
glassy state depending upon the rate of cooling.
As shown in Figure 2 regardless of whether melts had originated from a
crystal line or vitreous solid; above the melting point (Tm) they are identical
and show the identical decrease of volume with temperature along AB. If the
rate of cooling is slow, crystallization occurs if i) There is a sufficiently large
number of nuclei forming in unit time (nucleation frequency) and ii) The
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 123
linear growth rate of these nuclei are large enough. The volume is decreased
sharply along BC, upon further cooling of the crystal so formed shrink along
the crystal line to point D. If the rate of cooling is sufficiently rapid, a super-
cooled liquid is obtained. As temperature decreases, the structure of the liquid
continues to rearrange, but no abrupt decrease in volume observed, due to a
discontinuous structural rearrangement occurs. As cooling continues, the vis-
cosity of the system is rapidly increases. At sufficient low temperature, the
molecular groups can’t rearrange themselves fast enough to reach the volume
characteristic of that temperature and the frozen liquid is now glass. This is
called glass transformation region and occurs over a range of temperature not
a fixed point. Therefore, every glass has its characteristic temperature (Tg) in
which only below it the material is glass. If the temperature of the glass is
held constant at T, which is a little below Tg, the volume G continue to
decrease slowly. Eventually it reaches the level G’ on the dotted line, which
is a smooth continuation of contraction graph BE of the supercooled liquid.
The properties of glass show a change with time in the vicinity of Tg. This
process by which the glass reaches a more stable condition is known as stabi-
lization. Above Tg no such time – dependence properties is observed. Because
FIGURE 2
Relationship between glassy, liquid, and solid states [47].
124 Aly SAeed et al.
of the existence of stabilization effects, the properties of glass depend to a
certain extent on the rate at which it has been cooled particularly through the
transformation range [48].
3.4. Structural theories of glass formation
The earliest glasses used by man where found in nature and provide to be
useful to early man it is not surprising that the desire to produce glasses at
will developed thousands year ago. Many theories were development to
explain the glass formations, which usually are grouped under the heading of
structure theories of glass formation.
3.4.1. Goldschmidt observations
The earliest and simplest theory of glass formation was based on the observa-
tions by Goldschmidt that glasses of the general formula RnOm from most
easily where the ionic radius of the cation R to the oxygen ion lies in the
range 0.2 to 0.4 since radius ratios in this range tend to produce cations sur-
rounded by four oxygen ions in the form of tetrahedral (Fig. 3) [48].
3.4.2. Zachariasen’s Rules
In 1932 W.H. Zachariasen published a paper “The Atomic Arrangement in
Glass”, which described the ability of various oxides to form glass and had
great impact on material scientists of the period. Zachariasen’s work placed
the understanding of glass structure and its relationship to composition on a
chemical basis for the first time.
Zachariasen considered the relative glass forming ability of oxides and con-
cluded that the ultimate condition for glass formation is that a substance can
form extended three-dimensional networks lacking periodicity but with energy
content comparable with that of the corresponding crystal network. From these
conditions, he derived four rules for oxide structure that allow selection of those
oxides that tend to form glasses. The rules are the following:
1. An oxygen atom is linked to not more than two glass-forming atoms.
2. The coordination number of the glass-forming atoms is small.
FIGURE 3
Tetrahedral form for glass [47].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 125
3. The oxygen polyhedra share corners with each other, not edges or faces.
4. The polyhedra are linked in the three dimensional network.
From these considerations, Zachariasen concluded that the following oxides
should be glass formers:
B2O3, SiO2, GeO2, P2O5, As2O3, Sb2O3, V2O5, P2O3, Sb2O5, As2-
O5, Nb2O5, and Ta2O5.
At the time of Zachariasen’s research, only the first five oxides above [in
bold] had been made into glasses, but since then glasses of two other oxides
[underlined] in the list have been prepared. Five others on his list have never
been successfully prepared as glasses [49].
3.4.3. Stanworth classification
Stanworth suggested three more criteria on the glass-forming tendency of
oxides. These three criteria are:
1. The cation valance must be three or greater
2. The tendency of glass formation increases with decreasing cation size.
3. The electronegativity should be between 1.5 and 2.1 on Pauling’s scale.
Accordingly, Stanworth divided all oxides into four groups according to the
glass forming ability. They are:
i. Strong glass formers, which form glasses by their own when the melts
of their oxides are cooled. e.g., SiO2, GeO2, P2O5, and B2O3
ii. Intermediate glass formers which form glasses by their own but only on
rapid cooling, e.g., As2O3, Sb2O3 etc
iii. Conditioned glass formers, which will not form glasses by their own but
each will do so when melted with suitable quantity of non-forming
oxides, e.g. TeO2, SeO2, MoO3, WO3, Bi2O3, Al2O3 and V2O5.
iv. Non-glass forming oxides, e.g. oxides of Tin and Chromium.
The main glass-forming oxides are SiO2, B2O3, GeO2, and P2O5 all of
which come from a certain area of the periodic table. They are oxides of ele-
ments with intermediate electro-negativity. These elements are not suffi-
ciently electropositive to form ionic structures, but also are not sufficiently
electronegative to form covalently bonded molecular structure. Instead,
bonding is usually a mixture of ionic and covalent, and the structures are best
regarded as three-dimensional polymeric structures. Oxides of other elements
around this group in the periodic table also show a tendency for glass forma-
tion. Oxides like Na2O, K2O, PbO and CaO which when added in a small
quantities to the glass network forming oxides produce drastic changes in the
properties (like melting point, electrical conductivity etc.) of the glass form-
ing oxides. Such oxides also modify the network structure of the glass and
hence they are termed as network modifiers. [49]
126 Aly SAeed et al.
3.5. Methods of Glass Preparation
Different techniques have been used to prepare amorphous/ glassy materials
in various forms like bulk, sheet, powder, thin films, etc (Fig. 4). The follow-
ing techniques are used to prepare amorphous/glassy materials [50-51].
1. Melt quenching
2. Sol gel technique
3. Thermal evaporation,
4. Sputtering,
5. Glow discharge decomposition,
6. Chemical vapor deposition,
7. Electrolytic decomposition,
8. Chemical reaction,
9. Reaction amorphization,
10. Neutron Irradiation etc,
Among the above, melt quench technique is the simple and widely used for
the preparation of glassy materials because of the following reasons,
i. Glass preparation and handling are very easy
ii. Speedy preparations of innumerable compositions of the glasses are pos-
sible.
iii. Ability to produce wide variety of new oxide glasses
iv. Bulk glasses can be prepared and comparisons can be made with pulver-
ized glasses
v. Simultaneously, both amorphous and crystalline nature can be obtained
in the same melt, etc.
Hence, melt quench technique is used to prepare different compositions of
SAT. SPT and SVT glassy compounds
3.5.1. Melt– quench technique
Glass is prepared by cooling the molten liquid form of the compound suffi-
ciently quickly (Fig. 4(b)). The cooling must be sufficiently fast to preclude
crystal nucleation and growth. The crystallization rate of an under cooled
liquid depends on the rate of crystal nucleation and on the speed with which
the crystal-liquid interface moves. These are strongly dependent on the
reduced temperature Tr =Tc-Tm and the under cooling Tr = (Tm-T)/Tm.
High values of viscosity reduce the crystallization front velocity and hence,
the crystallization rate. Cooling rate is a critical factor in determining glass
formation. Generally, the quenching rate is from 105 to 109 KS-1 depends
upon the preparation method and type of materials.
Various types of materials can be prepared in amorphous/glassy form
using the melt-quench technique. Table 5 gives various techniques used for
creating different cooling rates to produce various types of glasses [53-54].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 127
3.6. Properties of Glass
Glass is a solid that belongs to the disordered state of matter. The most
common names for it are non-crystalline solids or amorphous solids or sol-
ids with liquid like structure. From macroscopic point of view, glass is hard,
FIGURE 4
Schematic presentations of different methods for the preparation of glasses: a) Slow cooling, b)
quenching, c) R F. sputtering, d) thermal evaporation [51].
TABLE 5
Various techniques and different cooling rates [53].
Technique Cooling rate (KS-1)*
Sputtering, Evaporation
Melt spinning, extraction
Chill-block, Splat-cooling
Liquid Quenching
Air Quenching
Annealing
Large telescope mirror
Optical glass
Ordinary glass
109
106-108
105
102-103
1-10
10-5
3x10-4
10-2-10-4
*Kelvin/second
128 Aly SAeed et al.
difficult to deform, transparent because there are no irregularities to deviate
any light ray passing through it and easy to break (brittle substance). In
addition, it is isotropic, except if internal stress or a texture is present.
Under microscope, it looks like a continuous and homogeneous material; in
large scale, it might be inhomogeneous. When compared with crystal, like
crystal glass must be made of an extended three-dimensional lattice but the
diffuse character of x-ray scattering shows that, this lattice neither symmet-
ric nor periodic unlike crystal (Fig. 5). The density, the mechanical proper-
ties and the thermal properties of glasses are similar to those of the
corresponding crystal. However, unlike crystal, glasses do not have sharp,
well-defined melting point and don’t cleave in preferred directions. Practi-
cally, glasses are more preferred as host matrices than crystalline materials
because of their high transparency, ease of mass production and shaping,
chemical durability, and dispersibility of many additives at high concentra-
tion [54-55].
3.7. Different Types of Glass
There are different types of glasses such as silicate glasses, alkali silicate
glasses, boric oxide glasses, alkali borate glasses, alkali borosilicate glasses
phosphate glasses and so on. Since the present study deals with borate glasses,
the structure and properties of vitreous B2O3 and borate glasses are discussed
in the following sections.
3.7.1. Borate Glass
In B2O3 glass, the oxygen coordination around each B is only three, and
hence the basic structural unit is a BO3 triangle with B is slightly above the
FIGURE 5
Ordered crystalline form (a) and, (b) a random network glassy form of the same oxide [55].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 129
plane of three oxygens. All the three oxygen are bridging between neighbour-
ing triangles. Several authors believe that an important constituent of vitreous
B2O3 is the boroxyl group (Fig. 6).
This group is a planar ring consists of six-members, alternatively boron
and oxygen atoms. These groups are linked together in a three-dimensional
network by boron-oxygen-boron bonds as shown in Figure 6. The presence of
boroxol groups in B2O3 glass was confirmed from X-ray diffraction and
various spectroscopic studies. From the X-ray diffraction measurements, the
boron-oxygen and oxygen-oxygen distances in the boroxol groups were esti-
mated as 1.37Ao, 2.40 Ao respectively [57].
3.7.2. Alkali orate glass
B2O3 is a glass fobrmer and the boron ion is trivalent positive. The introduc-
tion of oxygen from a modifier oxide into boric oxide glass brings about one
of the two possibilities.
a. Creates non-bridging oxygen, and the oxygen co-ordination around the
boron remains three as shown by the following reaction.
FIGURE 6
Configuration of two boroxyl groups linked by a bridging oxygen -boron; O-oxygen [57].
130 Aly SAeed et al.
b. Converts boron from 3-coordination state to 4-coordination state as
shown by the reaction.
In the RO: group, the oxygen is fully bridging and one negative charge each
from oxygen satisfies the three positive charges on the boron ion. After the
conversion from BO3 to Bo4, all the oxygen remain bridging, the extra nega-
tive charges on the [BO3 group is satisfied by an alkali M+ ion in the vicinity].
An Increase in the Bo4 tetrahedral in the glass structure increases the connec-
tivity of the network, and hence flow related properties decrease and viscosity
increases. The addition of alkali oxide to glassy B2O3 causes the gradual
change in the co-ordination number of boron from three to four [58-61].
3.8. Applications of Glass in Nuclear Science
Interest in glass is due to its diverse applications, has been observed from
time immemorial. Glass as a material is comparatively relatively easy to pro-
duce as well as for synthesis in a wide range of composition. Chemical com-
position of the glass plays an important role in determining properties of
glass. Glass has many applications in laser eyewear, laser safety, nuclear
shielding for gamma ray and neutrons, water treatment, antibacterial, and
many applications [62-92].
3.8.1. Glass as a shielding material
Nowadays nuclear radiation has been used in a wide space of modern tech-
nology like medical, agriculture, drilling and exploration of oils….etc. Expo-
sure radiation doses may harm various types of cell at varying effects and due
to no lower safety radiation limit. International committee on radiation pro-
tection (ICRP) had developed the principle for utilization of radiation with
safety precaution by using “As Low As Reasonable Achievable ‘ ALARM’ “.
Radiation workers needs a high quality or suitable shielding materials for
reduction of unnecessary radiation dose to working personal Many studies
conducted on various materials that serve the purpose of radiation shielding
like normal and heavy concrete, foam and rubber...etc, and hence they are
promising materials in this regard. Glass materials are possible alternatives
with two advantages brought by their transparency to visible light and their
properties can be modified by using composition and preparation techniques.
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 131
Several glasses developed which can use as a shield for different nuclear
application because they accomplish the double task of allowing visibility
and excellent absorber for nuclear radiation like gamma ray and neutrons. A
good shielding glass should have high value of interaction cross-section and
the effect of irradiation in mechanicals, electrical, thermal, and optical prop-
erties should be small [93-94].
3.8.2. Glass as nuclear waste disposal materials
With the increased potential of the nuclear power and the associated repro-
cessing of the fuel, the disposal of radioactive wastes will become an increas-
ingly important consideration. Many nuclear wastes are currently sorted as
liquid solutions, which impose very stringent demands on containment mate-
rials. Glasses are whoever showing considerable promise as a means of stor-
ing nuclear waste. The stability of glasses considered to their possible use in
the disposal of radioactive waste. Many of the technique that has been devel-
oped to improve the reliability of structural glasses will be applicable to
glasses intended for radioactive waste disposal [95-96].
3.8.3. Glass as radiation detectors
The most common glass scintillators are cerium-activated lithium or boron
silicates. Since both lithium and boron have large neutron cross-sections,
glass detectors are particularly well suited to the detection of thermal (slow)
neutrons. Lithium is more widely used than boron since it has a greater energy
release on capturing a neutron and therefore greater light output. Glass scin-
tillators are however sensitive to electrons and γ-rays as well (pulse height
discrimination can be used for particle identification). Being very robust, they
are also well suited to harsh environmental conditions. Their response time is
10 ns, their light output is however low, typically 30% of that of anthracene
[98].
4. INTERACTION OF RADIATION WITH MATTER AND
DETECTION TECHNIQUES
4.1. Introduction
The detection, characterization, and effects of radiation are almost entirely
dependent upon their interaction with matter. The flows of charged particles
direct ionizing radiation” such as alpha particles, beta particles and electrons,
are strongly interact with matter and cause dense ionization in the medium,
because through coulomb interaction with matter it directly causes ionization
and excitation of atoms so they easily stopped in matter. To shield from alpha
particles, a thin sheet of paper is generally sufficient. For beta particles having,
those energies commonly encountered, a few millimeters of aluminum, or a
132 Aly SAeed et al.
similar material is sufficient. Indirect ionizing radiation (neutrons, γ-rays) are
radiation of particles or photons, which have no charge and during interaction
with matter can transfer energy to charged particles, nuclei, and atom electrons
due to electromagnetic or nuclear interaction. The high penetration of indirect
ionizing radiation makes them very difficult to stop [98].
In this chapter, we will focus our debate on indirectly ionizing radiation in
terms of the interaction mechanisms and detection methods.
4.2. Gamma Rays
Gamma radiation is electromagnetic radiation of high frequency and there-
fore high energy. Gamma rays are ionizing radiation and are thus biologically
hazardous [99].
4.2.1. Gamma Ray Sources
Natural sources of gamma rays on Earth include gamma decay from natu-
rally occurring radioisotopes such as potassium-40, and as a secondary
radiation from various atmospheric interactions with cosmic ray particles.
Some rare terrestrial natural sources, which produce gamma rays that are
not of a nuclear origin, are lightning strikes and terrestrial gamma-ray
flashes, which produce high-energy emissions from natural high-energy
voltages. Gamma rays are produced by a number of astronomical processes
in which very high-energy electrons are produced, such electrons produce
secondary gamma rays by the mechanisms of bremsstrahlung, inverse Comp-
ton scattering and synchrotron radiation. Large fractions of such astronom-
ical gamma rays are screened by Earth’s atmosphere and must be detected
by spacecraft. Notable artificial sources of gamma rays include fission such
as occurs in nuclear reactors, and high energy physics experiments, such as
neutral and nuclear fusion [100].
4.2.2. Interaction of Gamma Rays with matter
Knowledge of gamma-ray interactions is important to the nondestructive
essayist in order to understand gamma-ray detection and attenuation. The
interaction of gamma rays with matter is markedly different from that of
charged particles such as α- or β-particles. The difference is apparent in the
much greater penetrating power of γ-rays and in the absorption laws. Gamma
rays, which are electromagnetic radiations, show a characteristic exponential
absorption in matter, and have no definite range [101].
Gamma rays have many modes of interaction with matter which can
divided into three categories from point of view the importance of attenuating
gamma rays
i. Primary importance
1. Photoelectric effect
2. Compton scattering
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 133
ii. Pair production
1. Secondary importance
2. Coherent (Rayleigh ) electron scattering
3. Annihilation radiation
4. Fluorescence radiation
5. Bremsstrahlung
iii. Negligible
1. Thomson scattering from the nucleus
2. Potential scattering
3. Crystal scattering
4. Nuclear interaction
a. Nuclear photoeffect
b. Nuclear scattering
5. Radiative corrections to lower order processes
The first category of interactions is the most frequent and therefore we will
discuss them below in some details [102].
i) Photoelectric effect
In this effect, an incident photon ejects tightly bound electrons from an atom
or a molecule (Fig. 7), and the energy of the ejected electron is equal to the
difference between the incident photon energy and the energy of that electron
in its atom [102].
The energy carried away by the emitted electron can be found by subtract-
ing the binding energy from the incident photon energy, that is
EEE
eb
=−
γ (1)
FIGURE 7
Photoelectric effect interaction [100].
134 Aly SAeed et al.
where Eb is the binding energy of the electron, Eγ is the incident photon
energy and Ee is the emitted electron energy.
In this reaction, the conservation of the energy is possible through impart-
ing some momentum to the remainder of the atom. The possibility of the
photoelectric absorption tends to increases rapidly with both the decrease in
the photon energy and the increase in the atomic number of the irradiated
material.
In the case of the heaviest elements, the photoelectric absorption is rather
insignificant for gamma ray energies greater than one MeV. Also in the pho-
toelectric effect, the photoelectrons are mainly responsible for the ionization
produced by the low energy photons [71].
ii) Compton scattering
In this interaction, the photon, with incident energy Eγ, scatters from an
electron normally regarded as being free. The result is a photon of lower
energy
E
γ, and an electron recoiling with an amount of kinetic energy T
which depends on the scattering angle. The process is illustrated schemati-
cally in Figure 8 Energy conservation gives for the kinetic energy of the
electron as [103]:
TE Eb
=−
γ (2)
From energy and momentum conservation one can derive the ratio of scat-
tered (
E
γ) to incident photon energy (Eγ)
=+−
E
E
γ
γγ
εθ
1
11(cos ) (3)
where, θγ is the scattering angle of the photon with respect to its original
direction. For backscattering (θγ = π) the energy transfer to the electron EKin
reaches a maximum value
Em
c
Kin
max=
+
2
12
2
2
ε
ε
(4)
The Compton Effect occurs primarily in the absorption of high γ-ray energy
and low atomic numbers. The cross section for this process, given by the
Klein-Nishina formula, can be approximated at high energies by
σε
ε
cZ
=⋅
ln (5)
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 135
In Compton scattering only a fraction of the photon energy is transferred to
the electron. Therefore, one defines an energy scattering cross section [103].
σσ
γ
γ
cs c
E
E
= (6)
In addition, energy absorption cross-section
σσσσ
γ
ca ccsc
Kin
E
E
=− = (7)
iii) Pair production
A gamma ray with energy of at least 1.022 MeV can create an electron-posi-
tron pair when it is under influence of the strong electromagnetic field near a
nucleus (Fig. 9). In this interaction, the nucleus receives a very small amount
of recoil energy to conserve momentum, but the nucleus is otherwise
unchanged and the gamma ray disappears.
This interaction has a threshold of 1.022 MeV because that is the minimum
energy required to create the electron and positron. If the gamma ray energy
exceeds 1.022 MeV, the excess energy shared between the electron and posi-
tron as kinetic energy. This interaction process is relatively unimportant for
nuclear material assay because most important gamma-ray signatures are
below 1.022 MeV. The electron and positron from pair production rapidly
slowed down in the absorber. After losing its kinetic energy, the positron com-
FIGURE 8
The Compton effect [101].
136 Aly SAeed et al.
bines with an electron in an annihilation process, which releases two gamma
rays with energies of 1.022 MeV. These lower energy gamma rays may interact
further with the absorbing material or may escape. In a gamma-ray detector,
this interaction often gives three peaks for a high-energy gamma ray [103].
The probability of the three processes described above for barium is illus-
trated in Figure 10.
4.2.3. Attenuation of Gamma Rays
The attenuation of gamma ray intensity is due primarily to combinations of the
photoelectric effect, the Compton scattering effect, and pair production. In each
FIGURE 9
Pair production interaction [103].
FIGURE 10
The relative importance of the three major types of gamma-ray interaction with Barium (Xcom
program version 3.1).
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 137
case, the photon energy is absorbing by the energy transferred to kinetic energy
of an electron or an electron-positron pair. The photoelectric effect and pair pro-
duction are processes in which the gamma ray’s energy is mostly absorbed in the
material. The Compton Effect involves both scattering and absorption. Cross sec-
tion of an absorbing material of thickness x with an intensity of radiation I0 inci-
dent perpendicularly to the face of the material (Fig. 11), as the radiation is
absorbed in the material, the intensity will be I1=I(x) as it enters a thin slice of the
material of thickness Dx located a distance x, from the entrance face. Assuming
that the material absorbs some of the radiation, the intensity of the radiation as it
leaves the slice is I2 = I(x + Dx) and will be less. The change in intensity DI will
be( I1-I2) and will be a decrease (negative) that is proportional to the thickness of
the thin slice, Dx, and the intensity of the radiation, I(x), so that
∆∆
IX Ix x() ()
=−µ
(8)
The constant of the proportionality µ is called the linear attenuation coeffi-
cient; its value is dependent on the gamma ray photon energy. Equation (4-8)
is the standard relationship for a change in a quantity that is proportional to
that quantity and is the basis for the typical exponential relationship. Equa-
tion (4-8) can be rearranged as
I
Ix=−µ (9)
and rewritten as a differential equation
Ix
IX dx
()
()
=−µ (10)
FIGURE 11
Cross section of absorbing material of thickness x with incident radiation intensity I0 [102].
138 Aly SAeed et al.
By applying the boundary conditions, I(0) = I0 when x’=0, the methods of
integral calculus yields the familiar solution
Ix Ie x
()=
0
µ (11)
The functional dependence of I on the absorber thickness x is implied implic-
itly. If the natural logarithm is taken on both sides of equation (4-11), then
ln() ln()IIx
=−
0µ (12)
This equation is in the form of an equation for a straight line, y = a + bx,
where yIaIb== =−ln(),ln( ), ,
0µ and x = x. If ln(I) is plotted as a function
of x, then the results should be a straight line whose slope is negative and has
the value µ linear attenuation coefficient (in cm-1).
The total linear attenuation coefficient µ represents the probability of pho-
ton interaction per unit path length. The quantity µ is the sum of the probabil-
ity for each of the three processes, that is.
µ = t + s + π
where t is the linear attenuation coefficient for the photoelectric effect, and s
is that for the Compton Effect, and π is that for pair production. The coeffi-
cient µ is a function of the energy of the gamma rays and the absorbing sub-
stance.
Another useful concept is the half-value thickness, X½, which is the value
of the absorber thickness that reduces the intensity to the half.
when xX
12
120
,
IX IIe
e
X
X
X
12
12
12
1200
12
1
2
2
()
==
=
=
µ
µ
µln()
µ=ln
()
2
12
X (13)
The way for comparing the absorption of photons in different material is
to use the tenth value thickness (T.V.T.). The (T.V.L) is the thickness,
which reduces the initial intensity to one-tenth of its value; it is related to
the HVL by:
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 139
xXxx
110 1212
10 10
232== =
ln() ln()
ln() .
µ (14)
Several values of TVT for different materials and photon energies are listed
in Table 6 [104].
4.3. Neutrons
Neutron is a neutral subatomic particle that is a constituent of every atomic
nucleus, except ordinary hydrogen atom, it has no electrical charge and rest
mass equal to 1.67493x10-27 kg, neutrons and protons commonly called
together nucleons where they account for 99.9 percent of atom’s mass. The
English physicist James Chadwick discovered the neutron in 1932 and within
a few years of this discovery, many of studies were conducted on the new
particle [105].
4.3.1. Neutron sources
Since the discovery of the neutron, studies have shown that neutrons can be
produced in a variety of ways. Neutron sources and some of their properties
are discuss below in some details [106-108]:
I (α,n) reactions - These sources are often prepared bymaking an intimate
mixture of α-emitter and finely divided powder ofthe target substance (Fig.
12). 226Ra, 2l0Po, and 239Pu are common as α-emitters used in the past.
Recently, 241Am and 238Pu sources have been used. B, Be, Li, Na, and F are
used as target materials (Table 7) [106-108].
TABLE 6
Photon tenth value thickness in cm for Al, Fe, Pb and concrete [104].
Energy (MeV) Aluminum Iron Lead Concrete
0.05 21 1.6 0.25 18
0.1 50 8.1 0.37 49
0.2 70 20 2.03 77
0.5 101 35 13 111
1 139 49 29 153
1.5 170 60 39 188
2 198 69 44 218
3 241 81 48 265
4 274 88 48 306
5 300 93 47 338
140 Aly SAeed et al.
Beryllium is most commonly used since it gives the highest yield. These
sources emit neutrons, which have a spectrum of energies, up to about 10 MeV.
II Photoneutron reactions - Some nuclei will emit neutrons when exposed to
high-energy-rays (Fig. 12) The target substances are thus limited mainly to
beryllium and deuterium, which have low neutron binding energies (1.67and
2.23 MeV, respectively). These sources emit nearly monoenergetic neutrons,
generally below about 1MeV (Table 8) [106-108].
III Accelerator sources - Nuclear reactions caused by high-speed charged
particles impinging on a suitable target yield neutrons. Types of reactions
used are (α, n), (α, 2n), (p,n), (γ,n), and (d, n). Accelerator sources are useful
for producing monoenergetic neutrons over a wide energy range. Since these
machines produce very high-energy charged particles, many new target sub-
TABLE 7
(α, n) neutron sources [106].
Source Half life
Average neutron
energy (MeV)
Yield
n/s Ci
226Ra + Be 1600 yrs 5 1.7 × 107
226Ra + B 1600 yrs 3 6.8 × 106
222Rn + Be 3.8 d 5 1.5 × 107
210Po + Be 138 d 4 3 × 106
210Po + B 138 d 2.5 9 × 105
210Po + F 138 d 1.4 4 × 105
210Po + Li 138 d 0.42 9 × 104
239Pu + Be 24,000 yrs 4 106
TABLE 8
Photoneutron sources [106].
Source Have-Life Energy(MeV) Neutron Yield (per GBq)
Neutron Gamma
24Na/Be 15 h 0.967 2.754 3.4x104
24Na/D 15 h 0.263 2.754 3.3x104
28Al/Be 2.24 min 0.101 1.779 3.3x103
124Sb/Be 60.2 d 0.023 1.691 2.2x104
88Y/D 107 d .0152, 0.949 1.836, 2.734 2.3x104
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 141
stances can be used. Proton and deuteron accelerators of 10 MeV can produce
monoenergetic neutrons at all energies up to 27 MeV [108-110].
IV Reactors - The fission process in reactors produces neutrons with a spec-
trum of energy, extending up to approximately 11 MeV [110].
V Spontaneous fission sources - The neutron spectra from these sources are
similar to that produced by fission in reactors. These sources are desirable as
calibration sources since they have fission like spectrum. 252Cf is at present
the most notable of these types of sources [110].
VI Fusion neutrons - When light elements are fused to form a heavier
nucleus, neutrons are released. Two reactions of interest in fusion research
are[110]:
1
2
1
2
1
3
0
1
1
2
1
3
2
4
0
1
245
14 1
HH He
nM
ev
HHeHen Mev
+→ +
+→+
(. )
(. )
4.3.2. Classification of Neutrons by Energy
Neutrons are classified according to their energy because the type of reaction
that a neutron undergoes depends very strongly on its energy. Neutrons are
classified according to the following energy scheme [111-112]:
I. Slow neutrons: These are neutrons with energies less than 1kev, and
divided into three groups as follows
FIGURE 12
Two types of neutron sources [109].
142 Aly SAeed et al.
a. Cold neutron: The neutron with an average energy less than 0.025
eV, they produced by device which depends on the coherent scattering
of slow neutron.
b. Thermal neutron: Thermal neutrons are those, which are in thermal
equilibrium with molecules or atoms of the surrounding medium. The
energy distribution of this group of neutron can be represented by
Maxwell–Boltzmann distribution. The thermal neutrons have energy
of about 0.025 eV at room temperature. One may use 0.4 eV as the
upper limit of this energy range.
c. Epithermal neutron: The neutrons, which are cover energy range
from 0.4 eV to 1 keV.
II. Intermediate energy neutron: These are the neutrons of energies
between slow and fast neutrons, and which cover energy range from
1kev to 500 keV.
III. Fast neutrons: These are neutrons having energies from 0.5 MeV to 20
MeV, and are produced by many types of nuclear reactions.
I V. Relativistic neutrons: This range includes neutrons of energy greater
than 20 MeV.
4.3.3. Neutrons Interactions
The study of neutrons interactions with matter still forms a large part of the
present experimental work in the field of physics. There are a number of pro-
cesses, which a neutron can enter into while passing through matter. The
particular effect, which occurs, depends upon the properties of the substances
and the energy of the neutron.
The interactions of neutrons with nuclei are divided into two categories:
scattering and absorption.
I. Scattering reactions
In scattering interactions, the neutron interacts with a nucleus, but both par-
ticles reappear after the reaction. The importance of scattering becomes
greater, however, because the neutron can transfer an appreciable amount of
energy in one collision. The secondary radiations in this case are recoil nuclei,
which have picked up a detectable amount of energy from neutron collisions.
At each scattering site, the neutron loses energy and is thereby moderated or
slowed to lower energy. A scattering collision is indicated as an (n, n) reaction
or as:
nX
Xn
Z
A
Z
A
+→+
The two categories of scattering reactions, elastic and inelastic scattering are
described in the following paragraph [1].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 143
I1. Elastic scattering
In an elastic scattering reaction between a neutrons and a target nucleus
(Fig. 13), there is no energy transferred into nuclear excitation. Momentum
and kinetic energy of the “system” are conserved although there is usually
some transfer of kinetic energy from the neutron to the target nucleus. The
target nucleus gains the amount of kinetic energy that the neutron loses.
Elastic scattering of neutrons by nuclei can occur in two ways. The
more unusual of the two interactions is the absorption of the neutron,
forming a compound nucleus, followed by there-emission of a neutron in
such a way that the total kinetic energy is conserved and the nucleus
returns to its ground state. This is known as resonance elastic scattering
and does the neutron possess very dependent upon the initial kinetic
energy. Due to formation of the compound nucleus, it is also referred to
as compound elastic scattering. The second, more usual method is termed
potential elastic scattering and can be understood by visualizing the neu-
trons and nuclei to be much like billiard balls with impenetr able surfaces.
Potential scattering takes place with incident neutrons that have energy of
up to about 1 MeV. In potential scattering, the neutron does not actually
touch the nucleus and a compound nucleus is not formed. Instead, the
neutron is scattered by the short-range nuclear forces when it approaches
close enough to the nucleus [101,113].
FIGURE 13
Elastic collision, momentum and energy are conserved [111].
144 Aly SAeed et al.
I2. Inelastic scattering
When a fast neutron undergoes inelastic scattering (Fig. 14), it is first cap-
tured by the target nucleus to form an excited state of the compound nucleus;
a neutron of lower kinetic energy is then emitted, leaving the target nucleus
in an excited state. In other words, in an inelastic scattering collision, some
(or all) of the kinetic energy of the neutron is converted into excitation energy
of the target nucleus.
This excess energy is subsequently emitted as one or more photons of
gamma radiation, called inelastic-scattering gamma rays. The total energy of
these gamma rays is equal to the excess energy of the excited state of the
target nucleus. For elements of moderate and high mass number, the mini-
mum excitation energy, i.e., the energy of the lowest excited state of the target
nucleus above the ground state is usually from 0.1 to 1 MeV. Hence, only
neutrons with energy exceeding this amount can be inelastically scattered
because of nuclear excitation. With decreasing mass number of the nucleus,
there is a general tendency for the excitation energy to increase, so that the
neutrons must have higher energies if they are to undergo inelastic scattering
[101,113].
II Absorption reactions
Most absorption reactions result in the loss of a neutron coupled with the
production of a charged particle or gamma ray. When the product nucleus is
radioactive, additional radiations emitted later. Radiative capture, particle
FIGURE 14
Inelastic Scattering neutrons, the target nucleus, and the total gamma energy emitted is equal to
the initial kinetic energy of the incident neutron [111].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 145
ejection, and fission are all categorized as absorption reactions and are briefly
described below [112,113].
II1. Radiative capture
In a radiative capture, the incident neutron enters the target nucleus forming
a compound nucleus.
Z
AXn Z
AX+→
++
0
11
γ
The compound nucleus then decays to its ground state by gamma emission
and described by (n, γ) reaction, this process most common occurs with slow
neutrons. The compound nucleus resulting from this process has almost exci-
tation energy of the order of 8 MeV [114].
II2. Particle ejection
In a particle, ejection reaction the incident particle enters the target nucleus
forming a compound nucleus. The newly formed compound nucleus has been
excited to a high enough energy level to cause it to eject a new particle while
the incident neutron remains in the nucleus. After the new particle is ejected,
the remaining nucleus may or may not exist in an excited state depending
upon the mass-energy balance of the reaction [115]. Table 9 lists some exam-
ples of particle eject reactions.
II3. Fission
One of the most important interactions that neutrons can cause is fission, in
which the nucleus of a heavy atom splits into two smaller nuclei known as
fission fragments and emits large amounts of energy and additional free neu-
trons. Hence, fission products include free neutrons, photons in the form
gamma rays, and other fragments such as beta particles and alpha particles.
This reaction occurs with certain nuclei of high atomic and mass numbers,
and can be described by (n, f) reaction. The fission process can become a
chain reaction producing large amount of neutrons, which become source to
TABLE 9
Particle eject reactions [114].
Reaction Reaction Name
0
111
1
nX
YP
Z
A
Z
A
+→ +
(n, p) Reaction
0
12
32
4
nX Y
Z
A
Z
A
+→ +
α(n, α) Reaction
2nX
+→ +
(n, 2n)Reaction
146 Aly SAeed et al.
a nuclear reactor. The neutron energy required to cause fission depends on the
nuclear properties of the target. Thus 235U, for example, has a large cross
section for thermal neutron, whereas 238U undergoes fission only if irradi-
ated by fast neutrons [116].
4.3.4. Neutron thermalization
Since neutrons are neutral particles, they cannot lose energy via ionization;
hence, they are slowed down by collisions with nuclei. Fission neutrons are
produced at an average energy of 2 MeV with energy extending to 11 MeV
and immediately begin to slow down as the result of numerous scattering
reactions with a variety of target nuclei. After a number of collisions, the
speed of a neutron is reduced to such an extent that it has approximately the
same average kinetic energy of the atoms or molecules of the medium in
which the neutron is undergoing elastic scattering. This energy, which is a
small fraction of an electron volt at ordinary temperature (0.025 eV at 20.5
OC), is frequently referred to as the thermal energy, since it depends upon the
temperature of the medium. Neutrons whose energies have been reduced to
values in this region (<1eV) are designated thermal neutrons. The process of
reducing the energy of a neutron to the thermal region by elastic scattering is
referred to as thermalization, slowing down, or moderation. The material
used for the purpose of thermalizing neutrons is called a moderator; a good
moderator reduces the speed of neutrons in a small number of collisions, but
does not absorb them largely [46].
4.3.5. Neutron Attenuation
Although a neutron beam has a relatively long range, there are always some
neutrons absorbed in the matter. The characteristic quantity for this absorp-
tion is called attenuation coefficient and is denoted by (µ). For polyenergetic
neutrons, there is an exponential decrease in their intensity variation during
the passage of neutrons through the matter, such that
IIe
o
x
=−µ (15)
The attenuation coefficient has the unit cm-1 and in case of neutron physics,
it is also called macroscopic cross-section . The physical meaning of the
macroscopic cross-section is the probability of neutron interaction per one
centimeter. The quantity µ, divided by the density ρ of the target material is
called mass attenuation coefficient and is equal to
µ
ρσ= N
M
A (16)
where:
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 147
NA = Avogadro’s number,
M = the atomic or molar mass,
s = microscopic cross-section.
The macroscopic cross-section can be used for defining a quantity called
reaction rate RR. Its meaning gives the number of reactions per unit time.
RR V
=⋅Σφ
(17)
where
φ = neutron flux.
V = target volume.
The microscopic cross-section can be defined as the area within which the
number of nuclei – neutron reaction taking place. The unit of the microscopic
cross-section is cm2, but usually barn is used instead (1 barn=10-24 cm2).
The relationship between microscopic and macroscopic cross-section corre-
sponds to the physical meaning:
Σ=
=
σ
ρ
n
n
M
NA
(18)
where:
n = number of nuclei per unit volume.
ρ = the density of the material in gm/cm3.
The dependence of neutron microscopic cross-section on energy of the neu-
tron usually consists of three parts as in Figure 15.
The first part (E~1 eV) is called “1/v region”, because the dependence
approximately is proportional to 1/v, where v is the neutron velocity. In this
region
σσ σEE
E
v
v
o
o
o
o
()
==
(19)
where
s0= microscopic cross-section at the velocity v0 = 2200 m/s.
E0 = energy of the neutron at the velocity v0 =2200 m/s.
The second region (E from ~ 1 eV to ~ 103 eV) is characterized by
extremely large changes of the microscopic cross-section and is called “reso-
nance region”. In the third region, neutrons have high energy more than ~ 103
eV. In this region, the microscopic cross-section is approaching the geometri-
cal cross-section of the target nucleus [46].
148 Aly SAeed et al.
4.4. Detection Techniques
It is impossible to smell, see, taste, or sense ionizing radiation. Humans have
no senses for α, β, γ rays, and neutrons; therefore, one has to develop detec-
tors to replace the missing capability to see, smell, taste,or sense ionizing
radiation. The necessity for the measurement of radiation exposures origi-
nates from the fact that this type of radiation has to be surveyed, controlled,
and limited. Humans also have to be protected against unexpected exposures.
4.4.1. Gamma rays Detection
Photons of gamma rays must first produce charged particles in an interaction
process, which are then normally detected via processes of ionization, excita-
tion, and scintillation. The interactions of photons are fundamentally differ-
ent from those of charged particles since in a photon interaction process the
photon is either completely absorbed (photoelectric effect, pair production)
or relatively large angles (Compton Effect). The kinds of detectors commonly
used can be categorized as [117]:
i. Gas-Filled Detectors
a. Ionization Chambers
b. Geiger Counters
c. Proportional Counters
ii. Solid State Detectors
a. Scintillation Detectors
FIGURE 15
The dependence of the neutron microscopic cross-section on its energy [46].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 149
1. NaI(Tl) detectors
2. Plastic scintillators
b. Semiconductor Detectors
1. Ge(Li) detector
2. Si(Li) detector
iii. Personal Dosimeters
a. The Pocket Ion Chamber
b. The Film Badge
c. The Thermoluminescent Dosimeter
4.4.2. Neutrons Detection
All neutrons detection relies on observing a neutron-induced nuclear
reaction. Neutrons have mass but no electrical charge. Because of this,
they cannot directly produce ionization in a detector, and therefore cannot
be directly detected. This means that neutron detectors must rely upon a
conversion process where an incident neutron interacts with a nucleus to
produce a secondary charged particle. These charged particles are then
directly detected and from them the presence of neutrons is deduced.
Neutrons are generally detected through nuclear reactions that result in
prompt energetic charged particles such as protons, alpha particles, and so
on. Virtually every type of neutron detector involves the combination of a
target material designed to carry out this conversion together with one of
theconventional radiation detectors. Different techniques are employed
for neutron detection in different energy regions, for the reason that the
cross section for neutron interactions in most materials is a strong func-
tion of neutron energy [118].
1. Fast neutron detection
As we go higher in the neutron energy range, the probability that a neutron
will come in contact with the reaction components mentioned in previous
section of this review, becomes smaller. In this case, a material that will slow
down (or “moderate”) the fast neutrons is needed in order for our detector to
be of useful efficiency. Hydrogen is often used for this purpose (of slowing
down neutrons), and fast neutrons undergo elastic scattering while they are
being slowed down. The hydrogenous material used to slow down neutrons is
called a moderator and usually is several centimeters thickness and surrounds
the detector. However, one must be extremely cautious about the moderator
thickness due to the fact that neutrons may sometimes be completely stopped
inside the moderating material and not penetrate the detector’s active volume.
For neutrons in the intermediate energy range (keV) a couple centimeters
moderator thickness is required, but for higher ranges (MeV), it should be a
lot more (close to tens of centimeters) when the moderator material is poly-
ethylene or paraffin [119].
150 Aly SAeed et al.
2. Slow neutron detection
Traditional slow neutron detectors mostly utilize gas-based detectors or scin-
tillators and employ a converter material with large total cross section. In
these detectors, neutrons are converted to charged particles (typically a-parti-
cles) which can ionize the detector material and thus indirectly indicate that a
neutron interaction occurred [120].
a. BF3 proportional counter
b. Lithium scintillator
c. 3He proportional counter
d. Fission counters
We will mention some of the basic characteristics of the used detector in our
work.
4.5. Scintillation counters
Scintillation was the first method used to detect ionizing radiation. When
radiation loses energy in a luminescent material, called a scintillator or
phosphor, it causes electronic transitions to excited states in the material.
The excited states decay by emitting photons, which can be observed and
related quantitatively to the action of the radiation. Scintillators employed
for radiation detection are usually surrounded by reflecting surfaces to trap
as much light as possible. The light is fed into a photomultiplier tube for
generation of an electrical signal. There a photosensitive cathode converts a
fraction of the photons into photoelectrons, which are accelerated through
an electric field toward another electrode, called a dynode. In striking the
dynode, each electron ejects a number of secondary electrons, giving rise to
electron multiplication. These secondary electrons are then accelerated
through a number of additional dynode stages achieving electron multipli-
cations in the range 107–1010. The magnitude of the final signal is propor-
tional to the scintillator lightoutput, which, under the right conditions, is
proportional to the energy loss that produced the scintillation. Good scintil-
lator materials should have a number of characteristics. They should effi-
ciently convert the energy deposited by a charged particle or photon into
detectable light. The efficiency of a scintillator is defined as the fraction of
the energy deposited that is converted into visible light. The highest effi-
ciency, about 13%, is obtained with sodium iodide. A good scintillator
should also have a linear energy response; that is, the constant of propor-
tionality between the light yield and the energy deposited should be inde-
pendent of the particle or photon energy. The luminescence should be rapid,
so that pulses are generated quickly and high-count rates can be resolved.
The scintillator should also be transparent to its own emitted light. Finally,
it should have good optical quality for coupling to a light pipe or photomul-
tiplier tube. The choice of a particular scintillation detector represents
abalancing of these factors for a given applications [121-122].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 151
There are different types of scintillators that are classified into inorganic
and organic-based scintillators.
4.5.1. Inorganic scintillators
Inorganic scintillator crystals are made with small amounts of activator
impurities to increase the fluorescence efficiency and to produce photons
in the visible region. As shown in figure (4.10), the crystal is character-
ized by valence and conduction bands. The activator provides electron
energy levels in the forbidden gap of the pure crystal. When a charged
particle interacts with the crystal, it promotes electrons from the valence
band into the conduction band, leaving behind positively charged holes. A
hole can drift to an activator site and ionize it. An electron can then drop
into the ionized site and form an excited neutral impurity complex, which
then decays with the emission of a visible photon. Because the photon
energies are less than the width of the forbidden gap, the crystal does not
absorb them.
The alkali halides are good scintillators. In addition to its efficient light
yield, sodium iodide doped with thallium [NaI (Tl)] is almost linear in its
energy response. It can be machined into a variety of sizes and shapes.
Disadvantages are that it is hygroscopic and somewhat fragile. NaI has
become a standard scintillator material for gamma-ray spectroscopy.
CsI(Na), CsI(Tl), and LiI(Eu) are examples of other inorganic scintilla-
tors. Silver-activated zinc sulfide is also commonly used. It is available
only as a polycrystalline powder, from which thin films and screens can
be made. The use of ZnS, therefore, is limited primarily to the detection
of heavy charged particles. (Rutherford used ZnS detectors in his alpha
particle scattering experiments.) Glass scintillators are also widely used
[121-122].
FIGURE 16
Energy-level diagram for activated crystal scintillator [121].
152 Aly SAeed et al.
i. Sodium iodide – NaI(Tl)
This is the most commonly used scintillator material (Fig. 17), the excellent
light yield is the most notable property of NaI(Tl), and its response is nearly
linear over the significant energy range. It has come to be accepted as the
standard scintillation material for gamma-ray spectroscopy.
Photons striking a sodium iodide (NaI) crystal, which contains 0.5 mole
percent of thallium iodide (Tl) as an activator, cause the emission of a short
flash of light in the wavelength range of 3300-5000 A (in the ultraviolet
region). A photomultiply tube, which gives a pulse corresponding to the light
intensity, detects the light flashes; a multi-channel counter measures these
pulses. The output pulses from a scintillation counter are proportional to the
energy of the radiation. Electronic devices have been built not only to detect
the pulses, but also to measure the pulse heights. The measurements enable
us to plot the intensity (number of pulses) versus energy (pulse height), yield-
ing a spectrum of the source [123].
4.5.3. Organic scintillators
Fluorescence in organic materials results from transitions in individual
molecules. Incident radiation causes electronic excitations of molecules
into discrete states, from which they decay by photon emission. Since the
process is molecular, the same fluorescence can occur with the organic
scintillator in the solid, liquid, or vapor state. Fluorescence in an inorganic
scintillator, on the other hand, depends on the existence of a regular crystal-
line lattice. Organic scintillators are available in a variety of forms. Anthra-
cene and stilbene are the most common organic crystalline scintillators,
anthracene having the highest efficiency of any organic material. Organic
scintillators can be polymerized into plastics. Liquid scintillators (e.g.,
xylene, toluene) are often used and are practical when large volumes are
required. Radioactive samples can be dissolved or suspended in them for
FIGURE 17
NaI (TI) crystal detection technique [123].
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 153
high-efficiency counting. Liquid scintillators are especially suited for mea-
suring soft beta rays, such as those from 14C or 3H. High-Z elements (e.g.,
leador tin) are sometimes added to organic scintillator materials to achieve
greater photoelectric conversion, but usually at the cost of decreased effi-
ciency. Compared with inorganic scintillators, organic materials have much
faster response, but generally yield less light. Because of their low-Z con-
stituents, there are little or no photoelectric peaks in gamma-ray pulse-
height spectra without the addition of high-Z elements. Organic scintillators
are generally most useful for measuring alpha and beta rays and for detect-
ing fast neutrons through the recoil protons produced [124-126].
i. Stilbene crystal
The stilbene crystal (C14 H12 ) is the most commonly used organic scintilla-
tor, it has a density, ρ=1.16gm.cm-3, and contains 4.658 x 1022 hydrogen
atoms and 5.435 x 1022 carbon atoms.cm-3. The chemical composition of a
stilbene crystal shows that it consists of sufficiently light nuclei. Therefore, in
gamma quanta detection, the photo effect takes place only in the region of
low energies (Eγ<0.1 MeV). The effect of pair production becomes appre-
ciable in the region of gamma quanta of energies Eγ =1.5 MeV. However, the
contribution of this effect is not significant, because the pair production
cross-section at Eγ = 10 MeV is about 20 % to of the total cross-section.
Therefore, in a wide range of energies, the Compton effect is the predominant
process for gamma quantum interaction with the stilbene scintillator. The
electrons, generated as a result of the Compton scattering possess a continu-
ous energy spectrum in the energy range from zero to a certain maximum
value, Emax. For gamma quanta of energy Eγ the value of Emaxcan be calcu-
lated as below:
EE
E
E
x
max
.
=−
γ
γ
γ
10 511 2
(20)
where Emax and Eγ are measured in MeV.
The shape of recoil electron energy distributions strongly depends on the
recorded gamma-quantum energy Eγ and on the scintillation dimensions
because of the leakage of high-energy electrons beyond the scintillator. The
fast neutrons on passing through the scintillator may experience elastic and
inelastic scattering by the nuclei of the elements constituting the scintillator.
However, inelastic scattering occurs on heavy nuclei and the energy imparted
by the neutrons to these nuclei is not high. Moreover, heavy nuclei do not
generate light pulses in the scintillator. For this reason, a contribution of neu-
tron inelastic scattering is usually neglected for the registration by a scintilla-
tion counter. The fast neutrons can transfer to the nucleus the highest possible
154 Aly SAeed et al.
energy on elastic scattering by protons. In this case, at a head-on collision, the
neutron transfers its total energy to the proton (EP= En). However, in fact,
this shape is idealized, since there are a number of distortion factors, which
will distort the pulse shape. For stilbene crystals, three time-constituents of
decay have been discovered,fast component with effective decay time t0=
6x10-9sec., independent on the nature of the particle emanating the scintilla-
tion. The other two components have a decay time, which varies from about
0.35 to 10µsec. In scintillation excitations by protons, these two components
are approximately, twice as intensive as for scintillation produced by elec-
trons. The main advantages of the stilbene crystal are:
a. Absence of long-lived neutron activation products in the scintillator;
b. Improved response time;
c. Relatively high resolution compared with the NaI (Tl) crystal;
d. Relatively simple method for unfolding the measured pulse amplitude
spectrum compared to the complex gamma-ray spectrum by a singleNaI
(Tl) scintillation spectrometer, which is a quite difficult task. While the
disadvantage of the stilbene scintillator is that, it is affected by a sharp
increase or decrease of temperature and mechanical impacts. [127-128].
4.5.4. Helium-3 proportional counters
Neutron detection by 3He (Fig. 18) is base on the reaction
The cross section for this reaction is quite high for thermal neutrons (4500
barn at 0.025eV). Proportional counters filled with 3He are widely used,
especially in time-of-flight measurements. The efficiency of the counter can
be increased by increasing the pressure. The 3He spectrometer is still a useful
detector for measuring the neutron spectrum in the energy range 0.1 to 1
MeV [128].
2
3
0
1
1
1
1
3276He nHHkeV+→ ++
FIGURE 18
3He slow neutron detector.
GlASS foR GAMMA ANd NeutRoN RAdiAtioN ShieldiNG 155
5. CONCLUSIONS
In the present work, show a review of the Fast and slow neutrons, total gamma
rays, and pure gamma-ray shielding properties. The Barium is a good attenu-
ator for fast neutrons, total gamma rays and pure gamma rays. Boron is an
efficient attenuator for slow neutrons. The investigated glassy barriers were
found to be a good absorber for gamma rays under transparent conditions. On
the other hand some disadvantages were observed with neutrons such as the
required thickness for attenuate both fast and slow neutrons.
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... Finally, to closely examine the efficiency of the studied BSiBi glass shield, whether against neutrons or gamma rays, the half-value layer for both neutrons (HVL n ) and gamma rays (HVL γ ) was calculated using Eq. (14) 28,29 . ...
... Then, the experimental errors in both neutrons' macroscopic cross-section and gamma rays' attenuation coefficients were calculated by the Eqs. (15 and 16) 12,16,25,28,29 . ...
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A successful attempt to produce a multi-function glass shield for attenuating neutrons and gamma rays by reinforcing a silicate glass network with boron and bismuth has been accomplished. A composition of 20SiO2-80Na2O (BSiBi0) was proposed to be used as a host glass network and prepared using the melt/annealing techniques. The low concentration of SiO2 in BSiBi0 was not sufficient to form a stable glass network. Then, the proposed BSiBi0 was modified with 10, 20, 30, and 40 mol% of each of B2O3 and Bi2O3 (BSiBi1, BSiBi2, BSiBi3, and BSiBi4) simultaneously. The structural effects of adding B³⁺ and Bi³⁺ were studied through X-ray diffraction, density, and FTIR, which all showed enhancement of glass forming ability, a former role of Bi³⁺ ions, and crowded the glass network by BO4 units. The derived structural parameters -- molar volume, mean silicon – silicon separation, mean boron – boron separation, oxygen packing density, packing density, and number of bridging/non-bridging oxygen -- were extensively discussed to explore the impact of B³⁺ and Bi³⁺ on the formed network. The richness of the proposed host glass network by B³⁺ and Bi³⁺ enhanced its thermal stability. The obtained elastic properties by ultrasonic measurements reflect the increase of the glass rigidity with increasing concentrations of B³⁺ and Bi³⁺ ions. The obtained glasses have high visible light transparency and almost complete UV absorption. The measured shielding parameters against two types of neutron energies (total slow and slow) and a wide range of gamma rays’ energies showed a significant improvement in the shielding efficiency of the considered glasses. The total slow neutrons, slow neutrons, and gamma rays’ attenuation abilities were improved by 22.9, 135.5, and 73.8 -- 199.5%. High thermal stability, elasticity, visible light transparency, and neutrons and gamma rays’ attenuation performance features give the produced glasses, especially BSiBi4 glass, preference as shielding materials in nuclear fields.
... Therefore, in recent times, the interface between radiation and materials has become a significant consideration for physicists and researchers to avoid the negative impacts of these radiations on humans. Effective protection depends on the principle of "As Low As Reasonably Achievable" (ALARA), which involves optimizing thickness, time, and distance [35]. Concrete, polymers, and nanomaterials can be used in the radiation shielding field [36,37]. ...
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This research investigates the impact of incorporating low-cost MnFe2O4 spinel nanoparticles (MF-NPs) at varying concentrations (0.5, 1, and 2 mass%) on the mechanical and physical properties of blended cement pastes. These pastes were produced by replacing different proportions (5, 10, and 15 mass%) of ordinary Portland cement (OPC) with activated alumina sludge waste (AAS), to promote sustainability. Also, the research examined the gamma radiation shielding effectiveness of certain hardened composites against a ¹³⁷Cs gamma radiation source with an energy of 661.64 keV using a NaI (Tl) detector (Oxford Model) with 3″ × 3″, amplifier and 16 k multi-channel analyzer. The linear attenuation coefficient (LAC) of all the studded samples were calculated theoretically using a Monte Carlo code MCNP-5 code. The gamma radiation shielding properties were analyzed in depth using a Monte Carlo code MCNP-5 simulation model. The theoretical and experimental results for LAC were found to be in complete agreement. Phy-X/PSD software was applied to estimate the mass attenuation coefficient (MAC) for gamma radiation at various energies, as well as the effective atomic number (Zeff), mean free path (MFP), half-value layer (HVL), and tenth-value layer (TVL). The findings demonstrated that the addition of 0.5% MnFe2O4 nanoparticles (MF-NPs) to blended cement pastes exhibited the best physical and mechanical characteristics, as well as the most effective gamma radiation shielding.
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Being one of the most important tools in industrial and medical fields, the red-NIR laser has caught a lot of attention in research studies to improve its emission efficiency and the stability of its lasing materials, both thermally and mechanically. In this regard, the emission intensity of the red-NIR laser generated from Er³⁺ ions doped glass network was enhanced by adding Yb³⁺, Nd³⁺, and Ce³⁺ ions. A host glass network of 44P2O5–15ZnO–10Pb3O4–15NaF–15MgF2–1Er2O3 was proposed as a red-NIR lasing material and was reinforced by 0.5 and 1 mol% of Yb³⁺, Nd³⁺, or Ce³⁺ ions (labeled as PZPbNMEr³⁺:RE³⁺). The structural variations resulting from compositional changes, which were examined by XRD, density, FTIR, and Raman measurements, showed an increase in the glass network tightness, leading to better thermal stability and elasticity of the considered PZPbNMEr³⁺:RE³⁺ glasses, indicating their suitability as lasing materials. Optically, all the distinctive optical absorption bands of the Er³⁺, Yb³⁺, Nd³⁺, and Ce³⁺ ions appeared in the spectral region of 200–2500 nm. Additionally, a significant impact of the induced strain or crystal field of the added RE³⁺ ions on the optical properties was observed. A successful excitation was conducted by the green wavelength of 525 nm to the host glass PZPbNMEr³⁺, generating five wavelengths, one in the red region at 631 nm and four in the NIR at 748, 801, 1034, and 1527 nm. A significant enhancement in the intensity and redshift of the formed bands were observed with the inclusion of Yb³⁺, Nd³⁺, and Ce³⁺ ions, and new NIR bands were generated. Additionally, an energy transfer between Er³⁺/Yb³⁺ and Er³⁺/Nd³⁺ was observed. Accordingly, the considered PZPbNMEr³⁺:RE³⁺ glasses had highly efficient photoluminescence in the red-NIR region alongside their high thermal stability and good elasticity, making them a suitable choice for laser media.
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In the present work, a glass system with developed composition consisting of B2O3, ZnO, Na2O and Fe2O3 samples has been investigated. Glass samples were prepared using the melt quenching method and the density of the system was measured using Archimedes’ principle. Spectroscopic analysis using a gamma source and a high-purity germanium detector at four energies of 0.0595, 0.6617, 1.173, and 1.333 MeV emitted from Am-241, Cs-137, and Co-60 were used to determine the attenuation parameters of present glass composites. The sample containing 45 B2O3 + 10 Na2O + 40 ZnO + 5 Fe2O3 (coded BNZF-4) had the highest mass attenuation coefficient (MAC) value at all the energies discussed compared to the other composites. Whoever, the BNZF-1 sample had the lowest value at all ranges of energies. The transmission factors (TF, %) of the manufactured samples were calculated, at 0.0595 MeV (TF, %) values are 32.6429 and 6.4612 for samples BNZF-1 and BNZF-4, respectively. The statistical results demonstrated significantly better to increase the ZnO concentration in the sample, where the percentage of zinc oxide inside the prepared glass samples has the following direction BNZF -4 > BNZF -3 > BNZF -2 > BNZF -1. The significance of this study is that transparent, environmentally harmless glass composites with relatively high density have been prepared that can be used as shielding materials against gamma rays, especially at low energies.
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Presenting the fundamental topics in glass science and technology, this concise introduction includes glass formation, crystallization, and phase separation. Glass structure models, with emphasis on the oxygen balance method, are presented in detail. Several chapters discuss the viscosity, density, thermal expansion, and mechanical properties of glasses as well as their optical and magnetic behavior and the diffusion of ions, atoms, and molecules and their effect on electrical conductivity, chemical durability, and other related behavior. In addition to the effects of atomic structure on the properties of glasses, the effects of phase separation, crystallization, and water content, which are neglected in most texts, are discussed extensively. Glass technology is addressed in chapters dealing with the raw materials for producing glasses, batch calculations, and the melting and fining processes. The compositions, properties, and production of commercial glasses are also presented. A chapter is devoted to the use of thermal analysis in the study of glasses, including their crystallization behavior. This expanded, third edition, includes new chapters on doped vitreous silica and the, often overlooked, role of halides on glass formation and properties. In addition, solutions to all of the exercises at the ends of chapters are included for the first time in this edition. This introductory text is ideal for undergraduates in materials science, ceramics, or inorganic chemistry. It will also be useful to the graduate student, engineer, or scientist seeking basic knowledge of the formation, properties, and production of glass in support of their work.
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How much radiation is too much? This book examines the evolution, over more than a hundred years, of radiation protection standards and efforts to ensure radiation safety for nuclear workers and for the general public. The risks of radiation—caused by fallout from nuclear bomb testing, exposure from medical or manufacturing procedures, effluents from nuclear power, or radioactivity from other sources—have aroused more sustained controversy and public fear than any other comparable industrial or environmental hazard. The book clarifies the entire radiation debate, showing that permissible dose levels are a key to the principles and practices that have prevailed in the field of radiation protection since the 1930s, and to their highly charged political and scientific history as well.
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This work presents the molecular spectroscopic analysis of glass systems with a chemical composition wt% (x-42) B2O3. (100-x) Na2O.40ZnO.2Nd2O3 (where x=100, 95, 90, 85,80and75) and which were prepared using the melt quenching method. The X-ray diffraction analysis confirmed the amorphous nature of the prepared glass. The effects of Na2O content on the glass system influences the estimated values with changing of the boron network of BO3 and the BO4. The most active IR peaks were observed in the region from 400 cm⁻¹ to 1600 cm⁻¹. The FT-IR spectra were analyzed to determine and differentiate the various vibrational modes by applying a deconvolution method to them.
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This book, entitled The Properties of Optical Glass, is one of a series reporting on research and development activities on products and processes conducted by the Schott Group. The scientifically founded development of new products and technical processes has traditionally been of vital importance at Schott and has always been per­ formed on a scale determined by the prospects for application of our special glasses. The scale has increased enormously since the reconstruction of the Schott Glaswerke in Mainz. The range of expert knowledge required for that could never have been supplied by Schott alone. It is also a tradition in our company to cultivate collaboration with customers, universities, and research institutes. Publications in numerous technical journals, which since 1969 we have edited to a regular timeplan as Forschungsberichte - 'research reports' - formed the basis of this cooperation. They contain up-to-date information on the most var­ ious topics for the expert but are not suited as survey material for those whose standpoint is more remote. This is the point where we would like to place our series, to stimulate the exchange of thoughts, so that we can consider from different points of view the possibilities offered by those incredibly versatile materials, glass and glass ceramics. We would like to show scientists and engineers, interested customers, and friends and employees of our firm the knowledge that has been won through our research and development at Schott in cooperation with the users of our materials.