Re: Re: [fluka-discuss]: γ ray count problem using USRBDX

From: YANG Tao <yangt_at_ihep.ac.cn>
Date: Fri, 6 May 2016 17:32:57 +0800 (GMT+08:00)

Dear Mikhail!


Thanks a lot for your reply! It may be the problem of the FLAIR software in my computer, I got the correct result in the server. But I have some other problems as follows:


1. What's the difference of BEAMPART and PHOTON in my input file? The BEAMPART is indeed photon in my input, so the two settings are both correct, do you think so?


2. You set the fluence scoring instead of current scoring in the USRBDX card, Why do you set as this form, in my opinion, the COUNT of the photon number should be one-way current scoring. Besides, the output photon number is not the same for the two different setting of the USRBDX card. However, in formula calculations the results I/I0 should be 2.1E-4 and your input file gets the correct result(about 2.0E-4 _at_primary number is 1000), and the one-way current setting in USRBDX gets a much bigger result (~1.0E-3).
   
Could you solve the puzzles for me?


All the best!


Tao Yang


-----原始邮件-----
发件人: "Mikhail Polkovnikov <Михаил Полковников>" <pmk_at_ihep.ru>
发送时间: 2016年5月6日 星期五
收件人: "YANG Tao" <yangt_at_ihep.ac.cn>, fluka-discuss_at_fluka.org
抄送:
主题: Re: [fluka-discuss]: γ ray count problem using USRBDX


On 06.05.2016 04:21, YANG Tao wrote:

Hello, everyone!


I simulate the lead shielding effect for γ ray recently, but I got a strange result. Beam position is at (0,0,0) and the beam direction is in z-direction. The gamma rays were directed towards a simple cuboid lead block with 10.5 cm in thickness and 200cm*200cm in length and width. USRBDX score card has been used to obtain the transmission values, I/I0, where I0 and I are the incident and attenuated photon intensities. Theoretically, I0 is 1 photon/primary since the incident photon will all penetrate the front surface of the lead block, however, the result (31BIN, "rushe") always give ZERO result, it's confusing, where did the photons go? Additionly, the exit photon (32BIN, "chushe") also give a wrong results compared to other literature.
These problems have confused me for several days, so any help will be appreciated much!!!

Thank You!

Tao Yang

CAS




Dear Tao Yang,

If you are interested only in attenuation of primary photons, you can try these two USRBDX's:

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
USRBDX 109. BEAMPART 21. valeft qiankuai 1.in
USRBDX 1.0E-3 8.0E-4 1. 1. &





*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
USRBDX 109. BEAMPART 21. qiankuai varigh 1.out
USRBDX 1.0E-3 8.0E-4 1. 1. &


In - input fluence before lead block

out - output fluence after lead block

The value (out / in) is close to the formula calculations ( mu = 0.07102 cm^2/g, density = 11,35 g/cm^3)




Best regards,

Mikhail



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Received on Fri May 06 2016 - 13:05:10 CEST

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