Dear Vittorio,
Thanks for your detailed reply. Problems become clearer to me, but I still have some doubts.
1. <<The "fiction" you do in the simulation is to account all the energy lost by delta rays to the original particle interaction.<<
Reply: OK, indeed, the outside electrons cannot enter in the detector. However, if we assume that the radiation field only has gamma ray, it's reasonable to attribute the energy deposition causing by gamma incident (despite of the detail process inside the detector) to the gamma contribution to the eventual detector signal. Obviously, gamma has 100% contribution to the detector signal since it assumes that the radiation field only has gamma. Using USRBIN+AUXSCORE card inside the detector sensitive volume, then we respectively score energy depositon by selecting option "ALL-PART", "PHOTON" and "ELECTRON", thus, the total energy deposition (value:A), deposition by gamma(B) and by electron(C) are obtained. Simulation always shows that A≈C>>B. There is no problem that electrons inside the sensitive volume are also generated by the gamma, and A also corresponds to the detector signal. But if there is a method to suppress the gamma-generated electrons or other particles generated electrons in the sensitive volume, I don't know if I will obtain that B equals to A for electrons cannot be created by doing this, if it is true, we can simplify the contribution of different particles in the mixed radiation field to the detector signal.
2.<< Your detector will see only the effects of the particles crossing it. Each particle has a history, a "father" process/interaction which generated it, and "children" particles which were generated by the interaction. therefore the AUXSCORE card uses this information to understand how much energy deposition was caused by a gamma, neutron or whatever else effect.<<
Reply: as replied above, when I add an AUXSCORE card for PHOTON, the result seems to show that energy deposition of gamma only generates the 1st-generation electrons, and the 1st generation electrons also generate the 2nd-generation electrons and so on, FLUKA seems to attribute the energy deposition after the 1st generation electrons by gamma interaction to ELECTRON's contribution, thus, we get a maximum deposition value from electrons and we cannot evaluate the contribution to the detector signal from particles in the outside mixed field. Perhaps the problem should be simply solved, but I don't know the specific method.
3.<< If you need the full particle tree history following the primary interaction you can always use the USERDUMP card, but this can generate a lot of data.I would first try to have under control the simulation of the detector response for specific primaries. In real life you would do the same by calibrating your detector response with specific particles and specific energy relevant to your problem.Second you need to get familiar with the particle fluences and spectra at the detector using a few USRTRACK and USRYIELD cards.Only then you can introduce the mixed radiation field. This can be achieved by changing the source term.<<
Reply: This suggestion may be the "fold method" but it is too complex and hard for me. Nevertheless, I get the detector response function of different primaries, but the response function only corresponds to some simplified situations that the primary beam direction with respect to the detector longitudinal direction is respectively 0, 90, 180, 270 degree. In the real mixed field, the direction of coming particles has all the possible values, but it's impossible to calculate response functions of all orientations. So how to use the obtained response function or could you send me some detailed references?
Best regards!
Yang
-----原始邮件-----
发件人: "Vittorio Boccone" <dr.vittorio.boccone_at_ieee.org>
发送时间: 2016年11月25日 星期五
收件人: "YANG Tao" <yangt_at_ihep.ac.cn>
抄送: "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>
主题: Re: Re: [fluka-discuss]: Contribution of different particles to the detector signal !
Dear Yang,
1."> However, the computational results are strange, gamma, neutron, and electron all have energy deposition, the most contribution is from electrons
I don’t understand this phrase>"
reply: I mean gamma ,neutron and electron all have energy deposition in the detector sensitive volume, but the maximum deposition is given by electrons, but electrons have not penetrated into the detector.
I think I understand now your problem, and it's clearly not related to FLUKA. If the secondary (or further-generation) electron is generated outside of your detector and has not enough energy to penetrate the detector (or generate n+1 generation electrons and gamma which can) you should not bother about them as they will not affect your signal creation.
2. "> > 1. [….] what is the small deposition value given by gamma and neutron? Is it the Non-ionising energy losses (NIEL)
> I also partly don’t understand the question. Neutrons can generate nuclear recoils, which in turn ionise and excites atoms/molecules along the track. NIEL - when no nuclear reaction are involved - are essentially related to the stopping power effects which includes lattice displacement, etc…"
reply: Based on the interpretation of Alberto Fasso，if all the energy deposition is from electron ionization, why
do gamma and neutron have a energy deposition value?
You cannot generalize w/o specifying in detail the radiation field. Not all the energy is lost in FLUKA through electron for all the processes. You took out Alberto phrase from a more general context. Sure all the energy lost through ionization losses will generate low energy electrons or atomic/molecular excitations. The "fiction" you do in the simulation is to account all the energy lost by delta rays to the original particle interaction.
3. The contribution to what? If the don’t interact inside of the active area of your detector what are you supposed to include? The only thing you might want to include is radioactive decays if your radiation field contains particle which can activate materials.
> If I understand correctly your question, you are asking how to separate - in the simulation results - the effect from different particle sources which compose your radiation field. (I also don’t get completely the sense of the question, perhaps you should try to get some help around to reformulate the question.)
> Well the point is that you are modelling you simulation, so you can separate the sources and run the simulation cases separately so you can see the effect on you detector independently. I can’t suggest you the “two step method” as I don’t know/understand your specific simulation case.
reply: I mean the contribution to the total signal of detector. Indeed, what I want to do is to separate the effect from different particle sources which compose the radiation field. Unfortunately, I cannot simply separate the sources and run the simulation cases separately for the reason that the radiation field comes from a beam loss on the beam tube or beam injection on a dump, the radiation field is complex, gamma and neutron both have a complex spectrum and I don't know how to model it like a simple source. And I don't know whether the "two-step methods" could solve the problem.
Ok, it's good that you start to describe your mixed radiation field.
Your detector will see only the effects of the particles crossing it. Each particle has a history, a "father" process/interaction which generated it, and "children" particles which were generated by the interaction. therefore the AUXSCORE card uses this information to understand how much energy deposition was caused by a gamma, neutron or whatever else effect.
As Alberto write the DELTARAY card controls the threshold below which the electrons (generated by other particles) will be considered delta-rays and therefore included in the energy balance controlled by the AUXSCORE card associated to a specific particle type.
If you need the full particle tree history following the primary interaction you can always use the USERDUMP card, but this can generate a lot of data.
I would first try to have under control the simulation of the detector response for specific primaries. In real life you would do the same by calibrating your detector response with specific particles and specific energy relevant to your problem.
Second you need to get familiar with the particle fluences and spectra at the detector using a few USRTRACK and USRYIELD cards.
Only then you can introduce the mixed radiation field. This can be achieved by changing the source term.
Best
Vittorio
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Received on Fri Nov 25 2016 - 20:32:57 CET