Experimental Nuclear Physics - Science topic

I'm interested. We can do a review in NORMs; (Whatever it's type)

Everyone will do a task in it.

Those who are steady can contact with me through the email:

📷

Well, first what you can try is to click on the X4 or X4+ options that is present in front of that reaction (as I can see there are few publications present in the screenshot). When you click on the X4/X4+ you will be directed to a page that contains all the experimental detail about that reaction and also the measured quantities along with the cross-section presented in a table, possibly at the bottom of the page. You can just copy the data from there and use it at your convenience. I hope this works out for you.

Dear Yevhen Hrabovskyi ,

I am not a specialist in Nuclear Physics, but your question seems to be very interesting.

I found the following related link * and I hope some specialists will address your inquiry, meanwhile, it is a good research final question for students in atomic physics/modern physics II.

Best Regards.

* https://physicsworld.com/a/new-superheavy-isotope-and-excited-state-could-point-the-way-to-islands-of-stability/

I am now running a small production line manufacturing various types of CR-39 or PADCs - mostly to custom spec or buy in larger bulk from main manufactures. Worked for TASL for many years and still involved with the track etch technology.

Dear Felix Richter, please see the references attached to the Russian Wikipedia post on the reflection of neutrons.

https://ru.wikipedia.org/wiki/Отражатель_нейтронов

This will depend if you are going to talk about the use of nuclear energy for medical, industrial, agriculture or other applications, or you are going to talk about the use of this type of energy source for electricity generation.

In this last case, you should consider, among others, the following issues:

1- Type of reactor to be used and experience of the supplier.

2- Safety of the nuclear reactors to be used.

3- Legal and regulatory matters.

4- Technological infrastructure of the country.

5- Financing of the construction of the power plant,

6- Decommissioning of the reactors.

7- Final disposal of nuclear waste.

8- Workforce qualification and experience.

9- Government support.

10- Capacity of the electrical grid.

Major data evaluation libraries can give this. Still there are disagreements between the libraries. So, evaluation goes on depending the new experimental data.

Maybe his was the problem, when I try to match the core excess reactivity vs accumulated burnup trend for MCNPX simulation and recorded operational data. Simulation results show higher core excess compare to the operational data as if the actual accumulated burnup is higher the recorded accumulated burnup data.

- When calculating ephemeris in the most accurate models of EPM and in some DE models, only miserable corrections are obtained from the PPN formalism. The Newtonian gravitation remains in the basement of celestial mechanics and of the GR. To my point of view, and stem from the fact, that geodetic lines in the presence of masses get bent, the Newton’s gravitation law suffers from a fundamental flaw due to violation of the inverse square law, underlying it. Let's try to go down from generalizations to specifics.

For example, discussing the modification of the law of Newton, I will argue that the mass is not an invariant, and the APPARENT gravitational mass depends on the distance to the observer Ma = M (1+ KR), where, for particular body, K = const. To verify the validity of the modified law, one will have to a) recalculate the masses of all celestial bodies in accordance with modified law, and b) get the Shapiro amendment, which will also depend on the (apparent) mass. As a result, using appropriate Shapiro delay values, we may get confirmation of the modified law.

Nguyen Tri Toan Phuc You can use TALYS1.9(latest version) for alpha induced reactions and EMPIRE3.2(as other people also suggested this) , both the code adopt Hauser-Feshbach formalism for compound nucleus cross-section.For heavy ion induced reaction you can go with PACE-4 and EMPIRE3.2. All these codes are freely available.

Apparently NJOY is open source see link

Josch

Hey dear  Kumar

The idea to mention the gamma radiation sensititvity in Rad/h is applied when neutron tubes are used in a combined neutron and gamma radiation field.

Neutron tubes, typically He3 proportional counter tubes, are somewhat sensitive to gamma radiation as well. If the gamma field is high, then the tube may falsely start to count the gamma's as neutron pulses. The Rad/h indication means that the tube is insensitive for gamma radiation field till that declared value.

This gamma radiation seen by a tube is typically less of energy than a neutron pulse that would be detected by the counter. Some solutions exist to make a tube less gamma sensitive. Suppliers can use special coating, specific less sensitive gazes or a tube base preamplifier with an LLD potentiometer to cut of that low energy part to obtain a neutron tube that is less sensitive to gamma radiation.

I don't know with GEANT4 but similar simulations were performed using MCNP in the work below.

Are you looking for a mathematical procedure to remove either neutrons or gammas via the pulse shape technique?

Since you seem to have a system measuring neutrons and gamma rays. I was not talking about about a mono-energetic neutron source.

Regards,

You can download software from website but you must pay for licence to activate it. It is not very expensive. 

I can try to attach Angle,but I am not sure that it is possible to attach .exe file even if it is "hide" as .rar. 

Hi dear Eric.

I think that the temperature is around 600 degrees

Just confirm by clicking on the following links.

There is a special version so-called "ccfull-li" for 6,7Li CC calculations. I think you can download it from Hagino-san's homepage, or you can ask him for the code.

One can solve the Bateman equation with hypotheses (one group cross sections that were convoluted with the neutron spectrum, main decays, no self shielding and neutron spectrum change during evolution...). Then you can end with a simple differential equation you can calculate by hand.

You may obtain an idea of your composition under irradiation under some assumptions.

I have a friend who have suggested me the following companies which supply CNT based field emission source and I hope it could be helpful for others in the field

One can look for following links:

i)http://www.xinnanomaterials.com/Conductive%20Films_EN.html

ii)http://www.euclidbeam.com/?page_id=143

 iii)http://xinraysystems.com/index.php/carbon-nanotube-cathodes/

you can check it on the website below

see

"Nuclear Physics A

Volume 944, December 2015, Pages 204–237

Special Issue on Superheavy Elements"

 there you would find your answer

By chance, do you mean identifying the materials due to the X-rays induced by low energy deuteron bombardment?

In this kind of experiments since the radioactive beam is a secondary beam it comes with all sort of directions and position. You need post-tracking detectors that give you the incident angle of the beam on the target as well as the impact position.

You might need to run without target as a double check that your beam is not hitting any surrounding detectors or target frame. Usually the experimental target for this type of experiment is very thick for statistic reason.

Hope this will help.

The question is very fundamental for nuclear physics and it is a big area of research as what is done by James Lee Tracy Jr.

I join the idea that liquid drop model in its modern release (by considering some quantum efects) is the most performant one and much convenient to describe nucleus state and on other hand I think that if we look about the time-space dependency of interaction constants (which is a consistent field of fundamental physics), there is a possibility to find a unified model of both weak and strong nuclear interaction but personnaly i don't thing that will be a easy thing to formulate in regular maths...

Dear Torilov,

I thought getting the hint student must do some work. You have provided the answer without any work by the student.

v. Kumar

Dr. Sankaran Ananthanarayanan,  1. YOU ARE POOR IN BASIC RADIATION PHYSICS. 2. YOUR ANSWER LACKS CLARITY AND VERY VAGUE.  I am very sure about my experimental discovery of UV dominant optical emission following Cu or Ag X-rays from within the same excited metal atoms of Variable Energy X-ray Source, AMC 2084, U.K. (Braz. J. Phy., 40, no 1, 38-46,2010)

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332010000100007).  I have already  explained with unprecedented detail how the optical emission takes place in radioisotopes and XRF sources in the same paper.   

FIRST AND BEST REVIEW OF THE RESEARCH PAPER

Margaret West,*a Andrew T. Ellis,b Philip J. Potts,d Christina Streli,c Christine Vanhoof,e Dariusz Wegrzynekf and Peter Wobrauschekc, Atomic spectrometry update-X-ray fluorescence spectrometry, J. Anal. At. Spectrom., 2011, 26, 1919.

DOI: 10.1039/c1ja90038b http://pubs.rsc.org | doi:10.1039/C1JA90038B

Refer under the title: 2.3 Spectrum analysis, matrix correction and calibration procedures

Words of citation: The phenomenon of optical emission predominantly in the UV, which accompanies the emission of X-rays, gamma rays, and beta radiation from radioisotope sources and X-ray tubes was investigated by Rao. It was the first work in which the emission of UV radiation was confirmed experimentally and a possible explanation for the mechanism of the UV emission was given by the author.  https://www.researchgate.net/publication/273124068_24_FIRST_AND_BEST_REVIEW_OF_THE_RESEARCH_PAPER_publis

The reviewers already cited my plausible explanation for UV emission following X-rays. PLEASE NOTE IN MY QUESTION, I DID NOT ASK FOR ALTERNATE EXPLANATION, YET YOU TRIED TO PROVIDE ONE. 

I never came across any reference on what you said, 'photo and Compton electrons exciting valence electron to emit UV'.  And you have not cited any reference, when you said, "(photo and Compton) electrons which, in turn, in favourable cases, can excite the valence electrons to emit UV or visible light.In a particular metal, these are decided by transitions of energy levels allowed  by quantum mechanical rules.  

When I mentioned my work with Cu or Ag X-rays from AMC2084,UK, you provided your own explanation  on gamma rays. Your comment is totally irrelevant and very vague. 

You said, "The line emission spectrum of various elements are available from reference data published by National Standard Laboratories".  What you quoted is optical spectrum of metals at high temperatures.   What I have reported is UV dominant  optical emission from Cu, Ag, and Mo XRF sources and 57-Co  notably at room temperature. Please note radioisotopes and XRF sources emit a new class of atomic spectra of  solids (radioisotopes and  XRF sources) unprecedented at room temperature. If I understand correctly, you are trying to downplay the work done and confuse the readers. In this process, your ignorance of the subject  is exposed.

See my article:American Journal of Astronomy and Astrophysics

2014; 2(2): 8-19

Published online October 30, 2014 (http://www.sciencepublishinggroup.com/j/ajaa)

doi: 10.11648/j.ajaa.s.20140202.12

New force, global anisotropy and the changes in b-decay

rate of radioactive elements

Yuriy Alexeevich Baurov1, 2, Yuriy Grigoreyvich Sobolev3, 4, Yuriy Vasilevich Ryabov5

1Closed Joint Stock Company Research Institute of Cosmic Physics, 141070, Moscow Region, Pionerskaya, 4, Korolyov, Russia

2Hotwater Srl, Via Gioberti, 15, I-56024 San Miniato (PI), Italy

3Joint Institute for Nuclear Researches, Moscow Region, Dubna, 141980, Russia

4Nuclear Physics Institute, 250 68 Rez, Prague, Czech Republic

5Institute for Nuclear Research of Russian Academy of Science, 60 – the October Anniversary Prospect, 7a, Moscow 117312, Russia

Dear Rawaa,

to me it seems you have not yet got a proper answer. Let me try to do the job.

For neutrinos to oscillate into anti-neutrinos, both would have to be "the same" particle. How can this be when we call them differently? The answer is that, experimentally, we only observe "left-handed" neutrinos (it's not the perfect name, but left-handed refers to a certain quantum property called chirality), which are those which e.g. are produced in orbital electron capture of atoms or in beta^+ decays, and "right-handed" anti-neutrinos, which are emitted e.g. in beta^- decays.

The reason for this distinction is that the weak interaction only couples to left-handed particles and right-handed anti-particles (that's not 100% precise, but for neutrinos it's perfectly correct). Thus, if "right-handed neutrinos" or "left-handed anti-neutrinos" existed, we would not know about it at least by the experiments we have been able to do so far.

Thus, at the moment, we don't know whether neutrinos are identical to their anti-particles (in which case they would be called "Majorana fermions") or not (in which case they would be called "Dirac fermions"). Up to now, we have observed elementary DIrac fermions in Nature (e.g. the electron has a distinct anti-particle, the positron) and we have also observed non-elementary ("quasi-particle") Majorana fermion-like states in condensed matter systems (in graphene to be precise). However, for neutrinos we don't know at the moment.

What would in any case be needed for neutrinos to be Majorana is "lepton number violation". We are actually searching for reactions which violate lepton number (the most promising being "neutrinoless double beta decay"), but we have found none so far.

From the theory side, we have indications that lepton number is violated, but we don't know for sure without experimental proof:

-We know that neutrinos are massive, and from the theory side, there are many more possibilities for this to happen if the neutrinos are Majorana fermions.

-We know that the Standard Model (SM) itself does *not* conserve lepton number. This is often stated incorrectly in textbooks, because at the perturbative level, the SM does conserve lepton number: it is not possible to write down any SM-Feynman diagram that violates lepton number. However, on the non-perturbative level there are certain types of reactions called "spahlerons" which are known to violate lepton number.

Both these arguments are good motivations to make an experiment to look for lepton number violation, but both do not tell us for sure.

And now we are finally ready to answer your question: *if* neutrinos are identical to anti-neutrinos, *then* we could have oscillations between neutrinos and anti-neutrinos. In fact, such an oscillation is part of one particular Feynman diagram that would transmit neutrinoless double beta decay. This oscillation would be hugely suppressed by the small neutrino mass, making it quite hard to observe experimentally, but in principle it would exist. In fact, even the very first paper on neutrino oscillations by Bruno Pontecorvo studied neutrino/anti-neutrino oscillation - at that time we did not know of more than one neutrino. But we have not found these oscillations experimentally (maybe: yet).

I hope this answers your question.

Best regards,

Alexander

It is not just the size of the particle that is used to probe the nucleus but its de Broglie wavelength.  The smaller the de Broglie wavelength, the greater is the resolving power.  To probe the interior of the nucleus, you require a probe with greater resolving power or a probe that can scan smaller and smaller spatial regions.

Hi Buce,

You might be able to use the TRn card to transform the geometry. You could define the cone in (x,z,y) coordinate system and then tilt it according to the angle desired by specifying new coordinates (x',y',z'). You'll have to do a little bit of geometry, but I think that this is the easiest way. 

I recommend looking into Chapter 4, Section II of the MCNP manual.

Hope this helps,

Daniel

about the measurement of activity concentrations of primordial (238U, 232Th, 226Ra and 40K) and anthropogenic (137Cs) radionuclide's and gamma dose rate in environmental samples using HPGe and NaI (Tl) dedector.

Natural radioactivity in soil is mainly due to 238U, 40K, 232Th and 226Ra, which causes external and internal radiological hazards due to emission of gamma rays and inhalation of radon ant its daughters (UNSCEAR, 1988). Measurement of external gamma dose due to terrestrial sources is necessary not only due to its contributions to the collective dose but also due to variations of the individual dose related to the pathway. These doses strongly depends on the concentrations of 238U, 232Th, their progenies and 40K, presents in rocks and soil, which in turns depends upon the geology of the regions

Hi

I am interesting, but how I can be useful

Hi Mohamad,

For the first part of the question, I don't think so. The processes are separate, i.e. neutron activation produces V-52, which then beta decays into Cr-52. The answer for the second part is more complicated. One way to determine the "conversion factor" is through Monte Carlo calculations. You will find more information e.g. here: L. Barbot et al., Calculation to Experiment Comparison of SPND Signals in Various Nuclear Reactor Environments and L. Vermeeren, Neutron and Gamma Sensitivities of Self-Powered Detectors: Monte Carlo Modelling (both are conference papers, presented at ANIMMA 2015). Alternatively, you could obtain a "conversion factor" by calibrating the SPND response against activation measurements. However, depending on the SPND design etc., there may be a significant contribution from gamma rays to the total SPND response, and this conversion factor may not be exactly the same throughout the reactor.

Hope this helps,

Vladimir

According to the decay scheme of NNDC the level 7/2- level at 126-keV is populated only 1.3e-7% of the time and not 100% as you indicate.

Almost 100% of the 55Fe decays directly populate the ground state of 55Mn. So, one would not expect to see many 126-keV transitions.

As an aside the total internal conversion coefficient for a pure M1 of 126 keV in Mn is 0.01652 (see http://bricc.anu.edu.au/index.php) so it does not affect the gamma-ray intensity by much. The lack of 126-keV transitions is simply because the level is not

populated.

There have been many (proposed) devices called "Rubiatron" . Some years ago (twenty or more) Rubbia became interested into inertial fusion with heavy ions (I was involved in the design of a part of this machine) then he had an other idea and started to be interested in ADS (people were involved in the design of part of this device) and then he changed his mind...all these were called Rubiatrons.

We are waiting for the next...

All the best

Pino

Thank you professor

Well,

I need long irradiation for those reactions whose cross sections are very small.(mb) But for the reactions having  high cross section(b) we dont need to irradiate for a long time. And yes definitely activation foils like Nickel, Zinc, Molybdenum, Ti, Au, In etc  of  different threshold energy are required to monitor the neutron flux.. However we used SULSA to unfold the fast neutron spectrum. Though SULSA demands manual input unlike TALYS/ STAPRE.

Maybe I could answer the question if I knew something more about the RIB experiment which I do not find in Google, only this - http://www.seriouseats.com/2009/12/the-food-lab-how-to-cook-roast-a-perfect-prime-rib.html

Armen Buniatyan is right that it depends on the precision you need. But you can improve the usefulness of your final result by eliminating in advance those Legendre polynomials that cannot contribute to the angular distribution. This can be done by estimating the maximum angular momentum of the incident particle relative to the target nucleus for any given incident momentum in the centre-of-mass coordinate system. To illustrate, suppose the scattering is likely to be limited to s-wave and p-wave scattering (zero and one units of angular momentum), then the scattering data can be fitted by two coefficients only -- yielding two partial cross sections. If the scattering extends also to d-wave, then you have three coefficients and you will derive three partial cross sections, and so forth.

Derek Paul, Professor emeritus, University of Toronto.

.

Visit the home page of the Nuclear Data Section of IAEA and select CINDA, You can search for the requested report in the catalog of the nuclear literature in an interactive way.

Assuming that you have not altered the isotopic mixture, you should be able to use the standard abundance tables that go with each isotope.  I would use this table, or something very similar.  If you have changed the isotopics using mass-spec or diffusion or something else, then you would need to have measured the abundances.  However, from your question, it looks like you can just use the "natural" abundance fractions:

I think there must also be a NIST table on this as well, which should have exactly the same data, since all of these organizations talk to each other.  http://www.nist.gov/ is a very useful site of standard atomic & nuclear data, and compounds research on these subjects for the past 100 or so years.

Good Luck.  Let me know if you have further questions.

Andrew

 Essay on beta decay and theories are attached

Sorry, but the definition of "Flux" posted by Sathian is incorrect.

Flux has units of particles/unit area/unit time, and is usually written as particles/cm^2/second, or particles/m^2/sec. It measures the flow of "particles" crossing a unit surface per unit time in any direction. In some fields, you can replace "particles" with "energy". It is not defined with reference to "emission", although emission can be measured in flux units if you are so inclined.

You can look the following websites, where you need to provide the target, type of reaction and energy information as input.

Don't know why but only part of my response was 'uploaded' previously.

To continue the higher energy 2754 keV photopeak will produce single and double escape peaks at 2243 and 1732 keV, respectively (your energy calibration might be off a keV or so) and also produces a 511 keV ann' peak. You noted a peak at 846 keV and attributed it to 27Mg. 56Mn emits a photopeak at 846 keV. The main photopeak of 27Mg is at 843 keV, to confirm 27Mg (quite probable) look for the next most intense peak of 27Mg at 1014 keV (if 56Mn then you should see a peak at 1810 and possibly at 2113 keV). 

As noted earlier to properly answer your question one would need to know:

a) the neutron source (e.g., nuclear reactor, D-T, D-D n-generator, isotopic n-source, etc) and

b) the decay time between irr'n and the start of counting (also how long did you count the irradiated Al?)

Finally, off the top of my head the cross-section you listed for the 27Al(n,g)28Al reaction (12 barns) seems rather excessive - I'd check that too.

Hope this helps.  

Hi Arnaud, 

You should definitely use the ENSDF  http://www.nndc.bnl.gov/ensdf/ which is standard database in the feild regularily updated by recently published data. Ideal generator should parse standard ENSDF file. It was claimed that Decay4 http://arxiv.org/abs/nucl-ex/0104018 is able to do this function but one of author has removed the code of generator from the internet.

You can also contact your former boss  Francois Mauger, who is working on new physics decay generator able to take and parse ENSDF file.

I may recommend you to read some articles of Prof. T.S. Kosmas. Especially in Nucl.Phys.A829(2009)234–252 you can find a lot of information.

Yes!! Photon-photon scattering is possible. Indeed high-energy photons increase the probability, but the cross-section is extremely low and so a high photon flux is required. An alternative approach is to use low-energy high-intensity lasers, which modify the vacuum in a nonlinear manner leading to photon-photon scattering. I refer you to this article: Nature Photonics 4, 92 - 94 (2010) / doi:10.1038/nphoton.2009.261, with a nice summary here: Nature Photonics 4, 72 - 74 (2010) / doi:10.1038/nphoton.2009.277 .

Dimitrios is right when stating that TRIM and GEANT use different methods: SRIM/TRIM applies the semi-empirical model of Ziegler, Biersack and Littmark, whereas GEANT is a Monte-Carlo toolkit using interaction cross-sections that are either directly measured or extrapolated. It is quite usual that the results of the two codes do not fully agree. Typical errors are 10% or even larger.

For your application, the stopping of low energy ions, SRIM/TRIM is usually more accurate than GEANT and less fault-prone. You find details about the SRIM implementation and comparisons to data in the SRIM Textbook by James Ziegler (see first link).

A third method to check your result is the NIST ASTAR webtool that simulates stopping of Alphas in various materials. Just follow the second link.

PS: It don't think you simulated neutrons in GEANT because then the mean range should be much larger than for Alpha-particles.

Rather than answering your question in frequency, it would be more realistic to answer in energy, simply the frequency is so high that gamma ray behave more like a particle (photon) than a wave. The CGRO and other satellite experiment can detect gamma ray only up to several 100s GeV or < 1TeV = 1.E12 eV. Higher than that, the flux is so low that satellite instruments loss detection power or their discrimination power to separate gamma from much higher flux of cosmic rays. The Ground gamma ray telescope can detect gamma photons interaction with atmosphere via indirect measurement. The highest energy of gamma ray  of those experiments can reach approximately 1.E14 eV, in terms of frequency ~ 2.4E28 Hertz.

The answer is simple and not simple.  Obviously the main part is that they will be similar because the question involves chemistry.  The chemistry of the two are, of course, identical.  What is not identical is the size of the atom  (not much difference, but a small amount).  It also makes a slight difference if they actually react with the W into a deuteride or tritide or via some impurity in the W or if they are just adsorbed onto the surface.  The best solution is to make this a research problem if the small differences are important.

Maybe you need logistic sigmoid function.

As far as I know, the average nuclear charges need advanced Hartree-Fock solutions. Especially the Ionization Conjecture of the HF theory. The issue is a difficult theme in computational physics. Several related publications could be accessed through Google Scholar and Scopus

Some authors use emanation and exhalation interchangeably. The correct use is shown in your diagram. Radon in the pores is exhaled by diffusion if there is no movement (convection) of the gas in the pores. Radon is removed by convection if there is movement in the pores, gaps, and cracks in the material. Convection can be caused by temperature differences in the material, water intrusion, or pressure difference caused by movement of air across the surface of the substance or atmospheric pressure changes. Pressure differential in a structure can be caused by air movement (advection) or temperature differentials.

Hello -

Perhaps if you were to reissue your question in a more data and statistics oriented context, and included regression under the list of topics, you might get more suggestions from the 'statistical community' (where I belong). If you have any releasable data, especially if it could be shown graphically, that might be helpful in any discussion. However, just evaluating data, as discussed for another question under regression, someone (Theo Dijkstra) pointed out, can be misleading, so make sure any advice you get is not spurious, and fits with some theory under your 'subject matter.'

I was encouraged that it appeared that you might have realized that heteroscedasticity may be important. Many statisticians don't remember, or perhaps ever knew that. OLS is dreadfully overused. :-)

Finally, if someone suggests an hypothesis or 'significance' test, another historical accident of statistics, note that a p-value is a function of sample size and can be very misleading if one is used alone. I think it far more useful/practical to look at your regression coefficients and their standard errors - comparatively. But note that if you use multiple regression, that interactions can have some regressors masking others, etc.

Whatever the state of your question now, or any new one, I suggest you reach out to the statistical community, but take whatever you hear 'with a grain of salt.'

Could be fun!

Best wishes - Jim

Thank you,  I agree with Prof. Virk,  the radon problem is help human beings to determine the health risks due to radon doses. 

We use polymers to study the effects of alpha radiation or energy in the polymer material to help us in calculating that we want to calculate in our studies.

the same effects of radiation on the polymer may give us an evaluation to what will happen in the living cells such as lungs or stomach .

For measuring correctly you need a good calibration before you conduct the measurements.  You must be careful about the leakage of gas from the can or container in which you measure the concentration. 

It is also depends on the procedure of sample collection. 

There is a ratio between indoor radon and Radon releasing from water depending on the radium content in the water.

Thank you very much dear Mr Behnam Farid.

To the best of my understanding, the Pauli principle is a mathematical consequence of what we understand by a Fermion. Whether all particles must be fermions or bosons depends on theory, and perhaps on experiment. But if a particle fails to satisfy the exclusion principle, then it is not a Fermion. Similar comments might apply, say, to attempt to detect deviations from Pythgoras' theorem. A possible violation would mean either that the triangle was not right-angled, or that Geometry was not Euclidean.

In  general one can obtain specific heat from entropy e.g. c_V = T (dS/dT)_V (partial derivatives of course) etc.  and here  S is the entropy of the Fermi gas.

For certain heavy nucleus the resonance peak position corresponds to a thermal energy because in the nucleus structure, in terms of energy levels, when adding nucleons there are certain positions where the binding energy is significantly low.

Hello!

In low-energy heavy-ion fusion, the term 'Coulomb barrier' commonly refers to the barrier formed by the repulsive 'Coulomb' and the attractive 'nuclear' (nucleus-nucleus) interactions in a central (s-wave) collision. This barrier is frequently called fusion barrier (for light and medium mass heavy-ion systems) or capture barrier (heavy systems). In general, there is a centrifugal component to such a barrier (non central collisions). Experimenters may use the term 'Coulomb barrier' to the nominal value of the 'Coulomb barrier distribution' when either coupled-channel effects operate or (at least) a collision partner is deformed as the barrier features depend on orientation. To my knowledge, the terminology 'transfer barrier' has not been used much. In my view, it could be applied to the transfer of charged particles/clusters.

There is a vast literature on methods for calculating Coulomb barriers. For instance, the double-folding method is broadly used in the low-energy nuclear physics community. Based on this technique, there is a potential called 'Sao-Paulo potential' because it has been developed by theorists in Sao Paulo city in Brazil.

Hope this info is useful.

Cheers,

Alexis

Hello!

It can be determined from the quarter-point of the elastic scattering angular distribution. It is the angle where the elastic differential cross section relative to the Coulomb-point (or Rutherford) one is 0.25. This angle relates to the grazing trajectory. The grazing angle can be calculated using the formula for the distance of the closest approach in the Rutherford scattering. When this distance is equal to the sum of the radius of the projectile and the radius of the target, the projectile trajectory corresponding to the grazing angle touches the surface of the target nucleus.

Cheers,

Alexis

Dear prashanth,

Any detector as such is not designed for giving out only timing or only energy type of signals. The fundamental signal that any detector gives out as a response to radiation interaction in its active volume is a momentary pulse of current. Based on the way in which you process this momentary current pulse the system as a whole either acts as a timing based ( used only for counting purpose) or as a energy signal (used for extracting energy spectrum). My suggestion would be to continue to use whatever detector you have. To get the timing information you can just change the front end electronics from charge sensitive (current integrator) pre-amplifier to a current sensitive(current to voltage converter) pre-amplifier.

Assuming that the proper energy & geometry calibrations were performed for both methods & an adequate sample sizes & count times were used, did you allow for proper ingrowth prior to counting via gamma spec? I suggest waiting for at least 3 weeks after sealing the Marinelli beaker before gamma counting so that the Pb/Bi-214 daughters are in equilibrium with the Ra-226.

If you waited for ingrowth, then I would review all the calibrations-

NEUTRON DIFFRACTION is used to study the magnetic structure of crystals. It is based on the interaction between the neutron magnetic moment and the magnetic field produced by aligned electrons in the materials.

On irradiation of Rb, Ba or Tb salt with gamma rays from 241Am, correspondingly Rb, Ba or Tb X-rays are emitted, as does happen in the case of Variable Energy X-ray Source, AMC2084,U.K.. The latest findings reveal that from within the same excited atoms two more generations of X-rays are produced. X-rays first generate Bharat radiation with energy higher than that of UV at eV level that in turn generates a new class of atomic spectrum of the salt regardless of temperature. The nature of atomic spectrum (percentage of UV, visible (VIS) and near infrared (NIR) radiation intensities in gross light intensity) thus produced depends upon the X-ray energy. In clear words the nature of spectrum does not depend upon the element whether it is Rb, Ba or Tb.

Rb X-rays are emitted from rubidium sulfate during gamma irradiation from 241Am. Likewise, Cu X-rays are emitted during gamma irradiation of copper metal. Variable Energy X-ray Source AMC2084,U.K. provides these XRF sources.

The recent publication in 2010 reported experimental discovery of UV dominant optical emission from radioisotopes (radiochemicals such as 137-Cs, and metal sources like 57-Co). Beta, gamma, and Characteristic X-ray emissions first cause Bharat Radiation (predicted), which in turn causes UV dominant optical emission by valence excitation from within the same excited atoms of radioisotopes by a previously unknown atomic phenomenon, now known as Padmanabha Rao effect.

In 2013, discovery of Bharat Radiation in 12.87 to 31 nm in solar spectrum was reported.

Reference:

M.A. Padmanabha Rao,

UV dominant optical emission newly detected from radioisotopes and XRF sources,

Braz. J. Phy., 40, no 1, 38-46,2010.

E.Strub

I understand what you are asking that there might be some distribution of fission timescale... But, it is not so.. It has got much deeper implication on the dynamics involved in that time scale... Fission timescale as mentioned by Bohr Wheeler is 10-21 sec which is not verified experimentally, measurements shows only 10-18 sec only, so it raises the question what is happening for 10^3 sec, why it got delayed?

The question is why at all we get 10-18 sec timescale...Do we understand the reason.

It is a much argued topic for decades and it is still not understandable......People bring in viscosity and argue that viscosity increases with temperature which seem quite irrelevant...It require a much better explanation...

Dr. Ignacio Durian

My question is in the timescale where K shall vacancy still persist and the electron from other shell have not undergo transition to K shell. In the timescale before 10-18 sec, when the vacancy still persists , does the K shell electronic wavefunction at the position of the nucleus is different from filled K shell wavefunction?

It's Cherenkov Radiation, caused by the beta particles from 137Cs decay passing through the CsCl crystals. The small dimensions of the crystals and the relatively low activity per crystal results in relatively low intensity Cherenkov Radiation, and hence it could only be seen in the dark. In a pool-type nuclear reactor, the much larger volume of the water and the higher beta activity from fission products results in a much more intense Cherenkov emission. I've stood on a small reactor and looked down a view port, and can confirm that Cherenkov radiation is easily visible, and a beautiful site it is too (when you know you are shielded from dangerous levels of ionising radiation - when it's in the open environment and uncontained it would be more worrying than beautiful).