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September 2001 - June 2006
July 1996 - August 2001
Publications
Publications (136)
The high energy neutron generation facilities worldwide uses the Li(p,n) system for production of the quasi mono-energetic neutrons from epithermal to few hundreds of MeV. Among the facilities either self-standing thick Li target or Li foil supported on a target assembly is used. In case of a supported Li target, either low or high mass supporting...
A multi-shell single sphere moderating assembly has been designed and developed to measure the neutron spectra in which the optically stimulated luminescence (OSL) detector pairs (Al2O3:C + 6, 7LiF) were used. The response matrix of OSL detectors, covering 11 energy decades (from thermal to 100 MeV neutrons) at different depths of the sphere, was g...
nat Li(p, n) reaction is a versatile system for the generation of quasi mono-energetic neutrons from epithermal to few hundreds of MeV. The mono-energetic epithermal neutrons serve as a promising alternative source for boron-neutron capture therapy applications for cancer treatment, whereas the high energy reference neutron fields are used as calib...
In this work, measurements were carried out in a standard thermal neutron facility using CR-39 detector combined with boron converter to study the dose response of CR-39 for thermal neutrons and the implementation of spectrophotometric techniques to extend the response towards high dose equivalents. The dose dependent variations in the response of...
The UV–Vis spectroscopy has been found suitable for fluence measurement with CR–39 track detector when the track counting with optical microscope is difficult due to huge overlapping of tracks. In this work, the optimum etching duration has been determined for alpha particle measurement using CR–39 as detector and UV–Vis spectroscopy as characteris...
A simple and efficient approach has been developed for rapid assessment of α-particle fluence and/or dose using CR-39 detectors and FTIR spectroscopic technique. The variations in the functional group intensities in CR-39 detectors with respect to the α-particle fluence in the range of 8.56 ×10⁴ to 2.14 ×10⁷ cm⁻² from a²³⁹Pu source were analysed. M...
The study of neutron parameters from a thick natural graphite target is of immense importance for obtaining the background neutron energy and yield corrections in case of proton irradiation of low Z targets, where graphite is used predominantly as the supporting target material. There are few measurements with thick graphite target reported in lite...
Photo-neutron production in electron accelerator near the threshold energy has been studied by Monte Carlo simulation using the FLUKA code. A pencil beam of 10 MeV electron was incident normally on W, Ta, Pb and Bi targets and a CR-39 detector attached to the target was used as scoring region. In the simulation, photon and neutron spectra, yield an...
Tauc analysis is popularly used for the determination of optical band gap by extrapolating the linear portion of the Tauc’s plot and finding its intersection point at energy axis. In most of the studies, the data points in the linear portion of the Tauc’s plot are selected manually, which is time-consuming and the reproducibility in the selection p...
The neutron spectral yields from the Li(p,n) reaction has been considered as an important study due to its potential use as mono-energetic fast neutron source. This reaction has been studied at energies nearing Coulomb barrier for mono-energetic neutrons from ⁷Be ground state emissions and at energies beyond few tens of MeV to get the quasi mono-en...
To overcome the limitation of CR-39 at high dose region where large number of tracks are overlapped, the FTIR spectroscopic technique can be implemented for dose estimation. In the present work, CR-39 detectors were irradiated with alpha particles from 239Pu source having known doses up to 5.12 Gy. The detectors were subjected to chemical etching i...
Current research in the accelerator technology is focused towards achieving high energy, intense beams by minimizing conversion losses during beam acceleration. In such high current facilities, induced activity in structural materials become primary concern for radiation protection and materials like Ta and Nb, with low induced activity generation,...
Neutron dosimetry and spectrometry with a Ta target is of concern in an accelerator environment considering its enormous use in a proton accelerator. The Ta target has a unique advantage considering the generation of short half lived radionuclides upon interaction with protons. This advantage extends its use as the beam stopping material at various...
Presently accelerator facilities emphasizes on generating charged particles with enhanced energy and flux. The radiation protection practices at these facilities are considered in civil engineering designs and strictly implemented through different administrative, access control measures (Sarkar in Radiat Meas 45:1476–1483, 2010). However, concern...
While measuring the neutron dose in accelerator radiation environment using CR-39 detector for radiation protection purpose, LET (linear energy transfer) spectrometry method is implemented when the information about the radiation source term is unknown. In this work, the neutron dose has been measured for p+¹⁸¹Ta reaction at different proton energi...
Microwave induced chemical etching (MICE) has been successfully employed in reducing the etching duration using NaOH etchant. In this work, the MICE technique has been studied with KOH etchant to investigate the effect on the track development. Chemical etching (CE) has also been performed at different temperatures for a comparison purpose. Neutron...
Microwave induced chemical etching (MICE) has been successfully employed in reducing the etching duration using NaOH etchant. In this work, the MICE technique has been studied with KOH etchant to investigate the effect on the track development. Chemical etching (CE) has also been performed at different temperatures for a comparison purpose. Neutron...
As measurement of inhalation dose due to radon and thoron progeny is very important in indoor as well as occupational environments, the solid state nuclear track (LR-115) based passive progeny sensors such as Direct Radon Progeny Sensor (DRPS) and Direct Thoron Progeny Sensor (DTPS) are extensively used for this purpose. These detectors need to be...
In this work, FLUKA design of a beam shaping assembly (BSA) has been carried out for sealed D–T neutron generator to have application in BNCT. Out of several materials, the design has been optimized for tungsten multiplier, D2O moderator, TiF3 fast neutron filter, cadmium thermal neutron filter and bismuth gamma filter surrounded by lead reflector....
Ta is a commonly used backing material for many targets in nuclear reaction studies. When the target thickness is less than the range of bombarded projectiles, the interaction via Ta(p,n) reactions in the backing can be a significant source of background. In this study, the neutron spectral yields from the reaction of protons of different energies...
The thick target neutron yield from a 16O6+ beam on a thick Al27 target at 120- and 142-MeV (7.5- and 8.8-MeV/nucleon, respectively) incident energies is presented and compared with theoretical calculations. The theoretical estimates for the yield of a high-energy neutron was obtained using a preequilibrium (PEQ) heavy-ion reaction model (hion), wh...
Microwave induced chemical etching (MICE) has been established as a faster and improved technique compared to other contemporary etching techniques for the development of tracks in a CR-39 detector. However, the methodology could not be applied for LET (linear energy transfer) spectrometry due to lack of a calibration curve using this method. For t...
Energy distributions of neutrons emitted from the interaction of 20 MeV protons incident on a thick Be target were estimated at two angles (0° and 90°) with respect to the incident beam using activation foils as threshold detectors. A recently developed unfolding code GAMCD based on Genetic Algorithm and Monte Carlo methods was used to estimate the...
In this work, electron induced modifications on the bulk etch rate, structural and optical parameters of CR-39 polymer were studied using gravimetric, FTIR (Fourier Transform Infrared) and UV–vis (Ultraviolet–Visible) techniques, respectively. CR-39 samples were irradiated with 10 MeV electron beam for different durations to have the absorbed doses...
In this work, we have used CR-39 detectors to estimate the LET (linear energy transfer) spectrum of secondary particles due to 171 MeV proton beam at different depths of water including the Bragg peak region. The measured LET spectra were compared with those obtained from FLUKA Monte Carlo simulation. The absorbed dose (DLET), dose equivalent (HLET...
Neutron dose for proton induced reactions on the combination of 7Li and 181Ta target was measured using CR-39 detector and a neutron rem meter, at five different proton energies (8–24 MeV). In case of CR-39, the dose equivalent (H LET) was measured via linear energy transfer (LET) spectrometry method using the major, minor radii of each track and t...
The recently introduced microwave induced chemical etching (MICE) has been found to be a fast and effective etching technique for CR-39 detector. In the present work, the MICE technique was used to develop the neutron induced recoil tracks in CR-39 detectors. Special attention was paid in carrying out a systematic investigation to study the effect...
Solid polymeric track detectors (SPTDs), due to their insensitivity to low LET radiations and integrating nature of signal registration, are found to be effective and convenient for neutron measurements, particularly in pulsed and mixed radiation fields such as in particle accelerator environments. This paper in addition to reviewing some of the ex...
Effects of the duration of chemical etching on the transmittance, absorbance and optical band gap width of the CR-39 (Polyallyl diglycol carbonate) detectors irradiated to high neutron doses (12.7, 22.1, 36.0 and 43.5 Sv) were studied. The neutrons were produced by bombardment of a thick Be target with 12 MeV protons of different fluences. The unir...
Effects of the duration of chemical etching on the transmittance, absorbance and optical band gap width of the CR-39 (Polyallyl diglycol carbonate) detectors irradiated to high neutron doses (12.7, 22.1, 36.0 and 43.5Sv) were studied. The neutrons were produced by bombardment of a thick Be target with 12MeV protons of different fluences. The unirra...
Effects of high-dose neutron irradiation on chemical and optical properties of CR-39 were studied using FTIR (Fourier Transform Infrared) and UV-vis (Ultraviolet-Visible) spectroscopy. The primary goal was to find a correlation between the neutron dose and the corresponding changes in the optical and chemical properties of CR-39 resulted from the n...
The neutron dose is estimated by linear energy transfer (LET) spectrometry method for two reactions, viz. 1H+9Be and 1H+12C at 20 MeV proton energy using CR-39 track detectors. The LET spectrum is generated from the major, minor radii of each track and thickness of removed surface from each side of the detector due to chemical etching. Microdosimet...
CR‑39 detectors, widely used for neutron dosimetry in accelerator radiation environment, have also been applied in tissue microdosimetry by generating the linear energy transfer (LET) spectrum. In this work, the neutron dose has been estimated via LET spectrometry for 9Be (p, n) reaction which is useful for personnel monitoring around particle acce...
CR-39 detectors, widely used for neutron dosimetry in accelerator radiation environment, have also been applied in tissue microdosimetry by generating the linear energy transfer (LET) spectrum. In this work, the neutron dose has been estimated via LET spectrometry for (9)Be (p, n) reaction which is useful for personnel monitoring around particle ac...
During extravehicular activities (EVA) astronauts are exposed to intense radiation from solar flare events (SFE). Hence, the radiation shielding efficacy of space suits, in particular the helmets and extra vehicular visor assembly (EVVA) are imperative to safety of astronauts and ultimate success of the space mission. At West German Proton Therapy...
A systematic study on the measurement of neutron spectra emitted from the interaction of protons of various energies with a thick beryllium target has been carried out. The measurements were carried out in the forward direction (at 0° with respect to the direction of protons) using CR-39 detectors. The doses were estimated using the in-house image...
Monte Carlo simulations have been carried out using the FLUKA code to improve the neutron ambient dose equivalent [H*(10)] response of the ZReC (zirconium-lined portable neutron counter responding satisfactorily to neutrons up to 1 GeV) by
introducing various neutron absorbers in the system such as cadmium, gadolinium, natural boron, enriched 10B a...
A systematic investigation is carried out to optimize the recently established microwave-induced chemical etching (MICE) parameters for rapid development of neutron-induced recoil tracks in CR-39 detectors. Several combinations of all available microwave powers with different etching durations were analysed to determine the most suitable etching co...
This study is carried out to establish a correlation between optical absorbance and track density
in CR-39 detectors exposed to different fluences of D-T (14 MeV) neutrons. This can be useful in estimating the neutron fluence and hence the dose without involving the tedious track counting procedure, especially when the track density is extremely hi...
Fast neutron spectral yield from the interaction of 20 MeV protons with thick Be and C targets are measured using CR-39 detectors. An image analysing program (autoTRAK_n) dedicated for neutron spectrum generation and dose estimation is developed based on the analysis of greylevel variations within each track and is used in the present study. The mo...
An attempt has been made in the present work to estimate the neutron spectrum of a standard 241 Am-B source using CR-39 solid polymeric track detector and an in-house image analysis program autoTRAK_n. The program works on the principle of greyscale variations in and around the recoil tracks and calculates the track parameters such as diameter, maj...
An attempt is made to estimate the neutron spectrum using the CR-39 (Solid state nuclear track) detector and a new image analyzing program. For this purpose the earlier developed program (autoTRAK) is modified by introducing the required features such as angular correction for the recoil particles, fluence-to-dose conversion coefficient, detection...
Linear energy transfer (LET) spectrum in water in the range of 12 keV/μm to 382 keV/μm due to 14 MeV (D–T) neutrons is estimated using the track size parameters in two different types of CR-39 track detectors, viz. Intercast (1.5 mm) and Pershore (0.5 mm). Another set of CR-39s (Intercast) combined with 1 mm polyethylene (PE) radiators is exposed t...
Preface Particle accelerators have evolved over the last decades from simple devices to powerful machines and are having an increasingly important impact on research, technology, medicine and lifestyle. A quick glance over the well-known Livingston chart illustrates how spectacular this development has been, with an average increase of one and a ha...
This paper reports the measurement of high energy neutron component (E > 50 MeV) carried out at the Indus-1 (450 MeV) and Indus-2 (2.5 GeV) electron accelerators (RRCAT, Indore, India). The study is based on the registration of neutron induced fission fragments from bismuth radiators in the adjoint solid polymeric track detectors. These bismuth fis...
An algorithm and a computer program (autoTRAK) are developed for rapid and precise estimation of track parameters in solid polymeric track detectors (SPTD). In this work, an effort is made to determine the 3-dimensional (3D) parameters such as depth (or length) and angle of the tracks, which are usually difficult to estimate from 2D images. The bas...
The neutron ambient dose equivalent has been measured from 10B, 11B, 12C, 13C, 16O and 18O projectiles of energy 5 MeV/amu incident on a thick Al target at 0°, 30°, 60° and 90° with respect to the beam direction using a conventional dose equivalent meter. The calculated results obtained using previously reported empirical relations do not reproduce...
Neutron response of the systems containing high density polyethylene (HDPE) spheres coupled with different external metallic converters has been studied using the FLUKA Monte Carlo simulation code. A diameter of 17.8 cm (7 in.) of the moderating sphere is found to be optimum to obtain the maximum response when used with the neutron converter shells...
In this work, neutron measurements were carried out for the interaction of 60 and 67.5 MeV 12C, 57.3 and 65 MeV 13C ions with thick aluminium target by using CR-39 detectors and neutron rem meter. Both the detector systems were irradiated at different angles viz. 0°, 30°, 60°, 90° with respect to the beam direction. The normalized track density (tr...
In this study, the measured data of angular distribution of neutron dose equivalent due to neutrons arising from the bombardment of 19.8 and 30 MeV alpha particles on a thick aluminium target has been reported. These measurements have been carried out at the BARC-TIFR Pelletron Linac Accelerator Facility using neutron dose equivalent meters popular...
In this work, the 2-dimensional images of α-tracks in CR-39 detectors have been analyzed in terms of grey values to obtain the critical information such as track length and angle, which usually cannot be obtained by conventional optical microscopes. A user-interactive code has been developed for the automated track detection based on the average gr...
During low earth orbiting (LEO) missions space vehicles are continuously
bombarded with energetic protons from the sun and in the events of solar
flare (SFE), the proton flux sporadically increases by many orders of
magnitudes. The solar protons interact with the containment wall of the
vehicle producing high-energy neutrons with a broad energy dis...
In this work, neutron measurements were carried out for the interaction of 60 and 67.5 MeV C-12, 57.3 and 65 MeV C-13 ions with thick aluminium target by using CR-39 detectors and neutron rem meter. Both the detector systems were irradiated at different angles viz. 0 degrees, 30 degrees, 60 degrees, 90 degrees with respect to the beam direction. Th...
In the present work, attempts have been made to investigate the modification in particle track etching response of polyallyl
diglycol carbonate (PADC) due to impact of 2 MeV electrons. PADC samples pre-irradiated to 1, 10, 20, 40, 60, 80 and 100 Mrad
doses of 2 MeV electrons were further exposed to 140 MeV28 Si beam and dose-dependent track registr...
The directional distribution of the ambient neutron dose equivalent from 145-MeV (19)F projectiles bombarding a thick aluminium target is measured and analysed. The measurements are carried out with a commercially available dose equivalent meter at 0°, 30°, 60° and 90° with respect to the beam direction. The experimental results are compared with c...
Response matrix for CaSO4:Dy based neutron dosimeter was generated using Monte Carlo code FLUKA in the energy range thermal to 20 MeV for a set of eight Bonner spheres of diameter 3–12″ including the bare one. Response of the neutron dosimeter was measured for the above set of spheres for 241Am–Be neutron source covered with 2 mm lead. An analytica...
The procedure of chemical etching (CE) or electro-chemical etching (ECE) is an inevitable step to reveal the ion-induced latent tracks in solid polymeric track detectors (SPTD). In this work, a microwave-induced chemical etching (MCE) technique is introduced, for the first time, to etch the SPTDs with much less (about on tenth) time as compared to...
Response matrix for CaSO4:Dy based neutron dosimeter was generated using Monte Carlo code FLUKA in the energy range thermal to 20 MeV for a set of eight Bonner spheres of diameter 3–12″ including the bare one. Response of the neutron dosimeter was measured for the above set of spheres for 241Am–Be neutron source covered with 2 mm lead. An analytica...
Albedo dosemeters, usually based on thermo-luminescence detectors, have been frequently employed in personal neutron dosimetry. Their main advantages are the high sensitivity and the reduced angular dependence, whilst the disadvantages are the sensitivity to photons and the significant energy dependence of the response, which drops dramatically abo...
The neutron spectra from a Pb-covered and a bare (without Pb-cover) 241Am–Be (α,n) source were measured using thermoluminescent detector (TLD) pairs of 6LiF and 7LiF with high-density polyethylene (HDPE) multi-spheres of seven different diameters. A total of 8 distinct neutron response signals (including a bare mode exposure) were obtained from whi...
The results obtained from the activation foils measurement are unfolded using two different deconvolution methods such as BUNKI and genetic algorithm (GA). The spectra produced by these codes agree fairly with each other and are comparable with that measured previously for the same system using NE213 liquid scintillator and by unfolding the neutron...
The bremsstrahlung spectrum generated by the accelerated field emission electrons at the Is' of five superconducting TESLA accelerator modules driving the FLASH (Free Electron Laser in Hamburg) was analyzed using a batch of radiochromic (Gaf-EBT) films sandwiched between lead plates of different thicknesses. The photon doses transmitted through the...
The ion irradiation of polymeric solids induces numerous modifications in the polymer properties, thus increasing their applicability in various fields. The present work looks into the aspect of thermal modifications induced in the irradiated polymers by using the thermogravimetric (TG) technique. It has been observed that the degradation of polyme...
From the extensive investigations carried out since 1992 with the dosimetric ANPA-stack on 107 long-haul flights, it is possible to conclude that the cumulative dose per flight on a given route changes within less than 20% among different repeated routes, two different aircrafts (Boeings 747 and 767), and among different locations within the aircra...
The rate of energy loss of the impinging ion as it passes through succeeding layers of the target material gives information regarding the nature of the material and helps to calculate the range of the ions in a thick target in which the ions are stopped. In the present work, the range of 118MeV 28Si was measured in different types of polycarbonate...
The behaviour of ubiquitous radon (Rn222), thoron (Rn220) and their progeny in the indoor atmosphere generally reflect a complex interplay between a number of processes, the most important of which are radioactive α-decay, ventilation, attachment to aerosols and deposition on the surfaces. The present work involved a long-term (1997–2000) passive m...