Dear Sung Hun Kim,
first of all, please keep the mail exchange on the list, so that also other can contribute (I included your input to this email for documentation).
In your setup, you have a 18 MeV proton beam impinging on a water target, which is 2.5 cm thick.
Since the range of a 18 MeV proton is about 4 mm, only neutrons produced in the water can actually exit the target in the direction of the Na wall.
I ran you input and I found that the energy of neutrons escaping the target in the direction of the wall drops very rapidly from about 10 MeV.
Considering that the reaction 23Na(n,2n)22Na has a threshold of about 13 MeV, it’s not surprising that no 22Na are produced with a limited statistics.
You need to consider to run much more primaries or better to bias the problem.
Just as cross-check to convince yourself that 22Na are indeed produced, you can set the target to sodium.
Best regards, luigi
On 18 Jul 2016, at 01:37, Sung Hun KIM <ksh4249_at_hanyang.ac.kr<mailto:ksh4249_at_hanyang.ac.kr>> wrote:
Dear Luigi Salvatore Esposito,
Here is my input file.
And I also attached the output file of residual nucleus from RESNUCLE cards.
I hope there is my fault concerning to this problem…..
Thanks for your help, in advance!
Best wishes,
Sung Hun Kim
From: Luigi Salvatore Esposito [mailto:luigi.salvatore.esposito_at_cern.ch]
Sent: Saturday, July 16, 2016 12:53 AM
To: ksh4249_at_hanyang.ac.kr<mailto:ksh4249_at_hanyang.ac.kr>
Cc: fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: About Na-22 production from (n,2n) reaction of Na-23, when activation analysis
Dear Sung Hun Kim,
I tested that Na-22 are INDEED produced by a 18 MeV neutron beam on a Na-23 target.
There could be some problem in your setup. Maybe you might want to send the input file.
Best regards, luigi
On 15 Jul 2016, at 09:39, Sung Hun KIM <ksh4249_at_hanyang.ac.kr<mailto:ksh4249_at_hanyang.ac.kr>> wrote:
Dear all,
Hi, I am a graduate student at Hanyang University in Seoul, South Korea.
I am evaluating the activity of cyclotron and surrounding structures, when 18 MeV proton is irradiated on H218O target, and I am trying to compare this results with those of MCNP.
In this simulation, I found something curious on activation of Na-23.
In MCNP result, there are Na-22 isotopes from (n,2n) reaction of Na-23, which has pretty high radioactivity.
However, in FLUKA result, Na-22 isotopes are not produced at all.
I found some Q/A in fluka discuss website, that (n,2n) reaction does not occur with neutrons of below 20 MeV, and in FLUKA the compensation of this process will be done by modifying the weight of generated neutrons.
However, in my case, I have to evaluate the activities and the activities of Na-22 isotope from (n,2n) reaction of Na-23 isotope is important.
In this case, does FLUKA compensate the activity of no production of Na-22, too?
If not, how can I evaluate the activity correctly?
Your answer will be a great help in my research.
I am looking forward to hearing from you.
Best wishes,
Sung Hun Kim
------------------------------------------------------------------------------------------------------------------------------
Sung Hun Kim, MS-PhD integrated course
Department of Nuclear Engineering, Hanyang University
222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea
Office: +82-2-2220-4057, Fax: +82-2-2220-4054
Cell: +82-10-7242-4249
E-mail: ksh4249_at_hanyang.ac.kr<mailto:ksh4249_at_hanyang.ac.kr>
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Received on Mon Jul 18 2016 - 15:48:55 CEST