Dear Bo Yang
As I mentioned in my previous email, at low energy (more precisely below 50keV) the conversion coefficients are simply kerma in air and thus perfectly consistent with the value that you quote (5-7 pSvcm2).
The calculations by A.Ferrari et al used at higher energy start at 50keV. Lacking conversion coefficients at lower energy at the time the FLUKA routine was developed (before the year 2002) we used air kerma.
ICRP116 down to 10keV might be more reasonable. The more fundamental question however is which quantity to use at even lower energy (effective dose, skin dose?) Please see also a related discussion on this list in 2007
http://www.fluka.org/web_archive/earchive/prova/0706.html
It is always possible to implement whatever coefficients you consider more reasonable reasonable for the quantities you would like to score via the user routine fluscw.f
Cheers
Stefan
From: 杨博 [mailto:b-yang12_at_mails.tsinghua.edu.cn]
Sent: 20 September 2015 06:22
To: Stefan Roesler <Stefan.Roesler_at_cern.ch>
Cc: fluka-discuss_at_fluka.org
Subject: Re: RE: [fluka-discuss]: A bug for EWT74
Dear stefan
Thanks for your comments， Now I konw what happen for my situation，but I found there is an obvious inconsistency of dose conversion factor between FLUKA and ICRP74（ICRP116）for low energy photon. For example, for photon energy of 0.01MeV and ROT geometry, the effective dose per unit fluence provided by ICRP 116 is 0.0337 pSv*cm2, the effective dose per air kerma and air kerma per unit fluence provided by ICRP74 are 0.00326 Sv/Gy and 7.43 pGy*cm2,respectively and their product is 0.0242pSv*cm2. However， from FIG.12 in
http://info-fluka-discussion.web.cern.ch/info-fluka-discussion/download/deq2.pdf， the effective dose per unit fluence provided by FLUKA is 5~7pSv *cm2. I don't why there is a such big difference between FLUKA and ICRP reports , dose conversion factor from ICRP166 and FLUKA were attached. Thank you so much.
Best regards
Bo Yang
-----原始邮件-----
发件人: "Stefan Roesler" <Stefan.Roesler_at_cern.ch<mailto:Stefan.Roesler_at_cern.ch>>
发送时间: 2015-09-20 04:06:53 (星期日)
收件人: "杨博" <b-yang12_at_mails.tsinghua.edu.cn<mailto:b-yang12_at_mails.tsinghua.edu.cn>>, "fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>" <fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>>
抄送:
主题: RE: [fluka-discuss]: A bug for EWT74
Dear Bo Yang
If you score photon fluence in logarithmic bins you will see that below ~20keV the fluence in case of PE is much larger than in case of Al.
At the same time the conversion coefficient from fluence to effective dose is strongly increasing towards low energy below about 50keV, see Fig.12 in
http://info-fluka-discussion.web.cern.ch/info-fluka-discussion/download/deq2.pdf
Note that the conversion coefficient for photons used at low energies is air kerma, due to lack of a better coefficient at the time when the routine was developed (maybe better coefficients for effective dose and low energy photons exist now).
Thus the combined effect of a higher fluence for PE and a strongly increasing conversion coefficient causes the effect that you see.
btw, Fig 12 in the above note also shows the conversion coefficient for ambient dose equivalent which drops to zero below 10keV (due to the definition of ambient dose equivalent), thus simply cancels the larger photon fluence at low energy for PE.
Cheers
Stefan
________________________________
From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it> [owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it>] on behalf of 杨博 [b-yang12_at_mails.tsinghua.edu.cn<mailto:b-yang12_at_mails.tsinghua.edu.cn>]
Sent: 19 September 2015 12:15
To: fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>
Subject: [fluka-discuss]: A bug for EWT74
Hi，every fluka user：
Rencently，I keep trying to simulate the process of electron with monoenergy of 3MeV hitting Al and PE target with same thickness of 1mm and score the forward photon dose-eq and photon spectrum by USRBDX and AUXSCORE. I found that with the dose conversion factor of EWT74 the dose-eq (1.683E-4 psv/prim) generated by PE target is larger than that (1.179E-4 psv/prim) genrated by Al Target, while with the entry of AMB74 the dose-eq (1.088E-4 psv/prim) generated by Al target is larger than that (4.119E-5 psv/prim) genrated by PE Target and from the photon spectrum, the photon number generated by Al is more than that generated by PE in the all energy range as attached. I checked and rechecked my inputfile and no error was found ,I thick there is a bug existed for EWT74,and hope someone can pay attention to it and help me solve this qusestion because I have to doubt if the previous work using EWT74 is corrected , Thank you so much, the input file and orginal results was attached.
Best regards
Bo yang
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Received on Mon Sep 21 2015 - 00:37:40 CEST