Re: Re: [fluka-discuss]: Contribution of different particles to the detector signal !

From: YANG Tao <yangt_at_ihep.ac.cn>
Date: Fri, 25 Nov 2016 12:59:13 +0800 (GMT+08:00)

Dear Vittorio,
Thanks for your reply.

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.

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?

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.

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
> 主题: Re: [fluka-discuss]: Contribution of different particles to the detector signal !
>
> Dear Yang,
> you seem confused. Clearly when lower energy (or low penetrating) particles in a mixed radiation field are not interacting in your desired region of interest (detector) they will not contribute to the signal generation; that particle could be an alpha, a neutron which gets absorbed on the way to the detector whose byproducts are also not generating prompt radiation (radioactive decays) or whatsoever other particle which will fit the picture.
>
>
> > 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.
>
> > 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…
>
> > 2. How to evaluate the signal contribution of particles outside the detector? If I attribute the generated electrons causing by gamma entering in the detector sensitive zone to the gamma contribution (assuming it get a value A), and so do it for neutron (assuming it get a value B). A/B may be the contribution ratio of gamma to neutron. But do you know how to finish it? AUXSCORE card as a filter fails to finish since it scores the energy deposition inside the detector and always get the boring results that the maximum contribution is always from electrons. Whether or not the solution is using the so called "two step methods"?
>
> 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.
>
> Best,
> Vittorio
>
>
> > On 24 Nov 2016, at 17:30, YANG Tao <yangt_at_ihep.ac.cn> wrote:
> >
> > Dear FLUKA users,
> >
> > I have a confused problem about the contribution of different particles to the detector signal when the detector is placed in a mixed filed. The mixed field is mainly consist of gamma, neutron and electron. The sketch is shown in the attachment. I think I know how the signal is to be generated. When the gamma enter the detector sensitive zone, it will produce electrons by photoelectric effect, compton effect and pair effect, then generated electrons contine a further ionization. Similar process is applicable to neutrons except that neutrons are via some reactions. But electrons in the mixed field has a rather low energy that they cannot penetrate the detector shell.
> >
> > Using the USRBIN and AUXSCORE cards, I evaluate the signal by the energy deposition methods and the contribution of different particles outside the detector, i.e., the surrounding radiation field. However, the computational results are strange, gamma, neutron, and electron all have energy deposition, the most contribution is from electrons. I think the contribution of electrons is from the ionization process of the generated electrons in the detector by gamma and neutron incident, but not from the outside electrons. I have two doubts as follows:
> >
> > 1. If all the energy deposition is from electron ionization( http://www.fluka.org/web_archive/earchive/new-fluka-discuss/7931.html ), what is the small deposition value given by gamma and neutron? Is it the Non-ionising energy losses (NIEL)?
> >
> > 2. How to evaluate the signal contribution of particles outside the detector? If I attribute the generated electrons causing by gamma entering in the detector sensitive zone to the gamma contribution (assuming it get a value A), and so do it for neutron (assuming it get a value B). A/B may be the contribution ratio of gamma to neutron. But do you know how to finish it? AUXSCORE card as a filter fails to finish since it scores the energy deposition inside the detector and always get the boring results that the maximum contribution is always from electrons. Whether or not the solution is using the so called "two step methods"?
> >
> > Any help is appreciated.
> >
> > T. Yang
> >
> > CAS
> >
> > <sketch.bmp>
>
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Received on Fri Nov 25 2016 - 07:33:15 CET

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