RE: RE: [fluka-discuss]: Does it need special setting for neutron in polyethylene?

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Sun, 15 Dec 2013 19:42:09 +0000

Dear Yuanjie

To complement the recommendations provided by Sunil also you may consider using a DEFAULTS card. As your input does not contain the definition of your Polyethylene, what cross section did you consider for Hydrogen ?

Regards
Joachim


From: Sunil C [mailto:csunil11_at_gmail.com]
Sent: 10 December 2013 16:20
To: 毕远杰
Cc: Joachim Vollaire; fluka-discuss
Subject: Re: RE: [fluka-discuss]: Does it need special setting for neutron in polyethylene?

Hi

A couple of points perhaps may help.

It is worthwhile to keep in mind that 10 MeV proton is pretty much at the lowest boundary of the PEANUT model that handles such a reaction in FLUKA.

You could also try a couple of alternate methods,(both involving the use of source sub routine) to estimate what you require.

The neutron emission cross sections from such a reaction may be available in the EXFOR data base and if so, you can use that information. I could locate a few by a crude and quick search.
If you have access to a nuclear reaction model codes, the shape of the spectrum can be determined. The total neutron yield from a thick target may not be what you get when you use such a code to calculate just the cross section at the incident projectile energy, but the shape will be quite close.

Also, it is a good practice to use the "CH2 bound natural Hydrogen" cross section while using polyethylene and paraffin.

When you bombard a target with protons and try to calculate the neutron attenuation length, you are of course aware that the quantity you obtain is spectrum weighted average number. I would advice caution while comparing such a result with literature values.

Best Regards
Sunil

On Tue, Dec 10, 2013 at 5:17 PM, 毕远杰 <biyuanjie_at_tsinghua.org.cn<mailto:biyuanjie_at_tsinghua.org.cn>> wrote:
Dear Joachim,

I attach the input file. I use several slabs to calculate the attenuation length of neutron and photon in concrete and polyethylene.
The initial proton beam is 10MeV, which is near the reaction threshold.

Many thanks
Yuanjie


> -----原始邮件-----
> 发件人: "Joachim Vollaire" <joachim.vollaire_at_cern.ch<mailto:joachim.vollaire_at_cern.ch>>
> 发送时间: 2013年12月9日 星期一
> 收件人: ??? <biyuanjie_at_tsinghua.org.cn<mailto:biyuanjie_at_tsinghua.org.cn>>
> 抄送:
> 主题: RE: [fluka-discuss]: Does it need special setting for neutron in polyethylene?
>
> Dear Yuanjie
> Could you send your input file, it would be much better to understand your issue.
> Thanks in advance
> Joachim
>
>
> -----Original Message-----
> From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it> [mailto:owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it>] On Behalf Of ???
> Sent: 02 December 2013 12:31
> To: fluka-discuss
> Subject: [fluka-discuss]: Does it need special setting for neutron in polyethylene?
>
>
> Dear Fluka users,
>
> I use Fluka to calculate the attenuation length of neutron in different materials from 10 MeV proton impinging on iron target. The New-defaults is used. The results show that the attenuation length in concrete agrees with the literature data. But the attenuation length in polyethylene is much larger than the literature data. So the question is:
>
> 1) Does it need special setting for neutron in polyethylene?
> 2) Does it need special setting for 10 MeV proton which is almost the threshold of the (p,n) reaction except the setting of PART-THR?
>
> Many thanks
> Best wishes
> Yuanjie
>

Received on Sun Dec 15 2013 - 21:48:46 CET