Re: [fluka-discuss]: scoring heavy ions of nuclear reaction, how to obtain the ion fluence?

From: Francesc Salvat-Pujol <francesc.salvat.pujol_at_cern.ch>
Date: Fri, 8 Jun 2018 18:16:17 +0200

Dear Yang,

See the reply in-line:

> Dear Francesc,
>
> Thanks a lot for your suggestions, I ran it and got a non-zero results
> according to your methods(attachment boron.inp). However, I still have
> some problems about the input card.
>
> 1. In order to switch on heavy ion transport, what cards are necessary?
> In my input file, I switch on IONTRANS card and PART-THR card.

See the manual and the heavy ion lecture below, where this question is
addressed in detail:

https://indico.cern.ch/event/694979/contributions/2927128/attachments/1657656/2654334/Heavy_Ions_2018.pdf

> 2. As shown in the attached files(physicsCard.jpg), I set two PHYSICS
> cards, but I don't know whether they are suitable or not, and what is
> the general criterion to set the PHYSICS card?

Also discussed in the above lecture.

> 3. I score the heavy ion fluence by using USRBDX card, what(2) of the
> card is the particle. I select what(2) of the card "HEAVYION", does it
> mean the card will score all of the heavy ions, i.e., α and Li ion? if
> that is the case, how can I individually score the α and Li? HE-4 can
> be found in the drop-down menu of FLAIR, but Li can't be found.

Unless I'm mistaken, you could pass an AUXSCORE card to filter the
separate contributions to the fluence due to alpha and 7Li (see
WHAT(2) in that card).

> 4. PS2 in your last mail, you suggest it is suitable to set what(3) of
> EMFCUT card to a relatively low value (1e-5, I set to the lowest value
> 1e-6) ,but I don't why, could you explain it?

This parameter governs the fraction of atomic electrons which contribute
to multiple Coulomb scattering. For delta-ray production thresholds
well below typical electron binding energies (a few 10s of keV),
collisions with atomic electrons are effectively accounted for by
explicit delta-ray production, so WHAT(3) should be set to a very small
value. Conversely, for delta-ray production thresholds above a few 10s
of keV, WHAT(3) should be set to 1, otherwise collisions with these
atomic electrons would effectively not be accounted for.

> 5. In your last mail, you pointed out that "As a result of renaming your
> boron to BORON-10, and of the fact that pointwise cross sections are
> automatically active for 10B(n,alpha)7Li", is it applicable to the
> special situation(10B(n, α)7Li) or any other reactions that has heavy
> ion products?

The sentence was constrained to the case 10B(n,alpha)7Li.

Hope this helps!

Cesc

> Thanks again!
>
> Best regards!
>
> Yang
>
>
>
>> -----原始邮件-----
>> 发件人: "Francesc Salvat-Pujol" <francesc.salvat.pujol_at_cern.ch>
>> 发送时间: 2018-06-06 17:12:11 (星期三)
>> 收件人: "YANG Tao" <yangt_at_ihep.ac.cn>
>> 抄送: fluka-discuss_at_fluka.org
>> 主题: Re: [fluka-discuss]: scoring heavy ions of nuclear reaction, how to obtain the ion fluence?
>>
>> Dear Yang,
>>
>> Note that the feature you implicitly request (production and transport
>> of alpha and Li from B under n bombardment) needs pointwise cross
>> sections for low-energy neutrons. Furthermore, in the case of B it
>> should be kept in mind that pointwise cross sections are available in
>> FLUKA for the reaction 10B(n,alpha)7Li only.
>>
>> The next point to keep in mind is that the correspondence between FLUKA
>> material and low-energy neutron cross section material is done on a
>> material-name basis (often requiring some extra identifiers in the
>> name).
>>
>> The way you had B in your input file (named BORON), FLUKA was picking
>> up the low-energy neutron cross section for natural B, the first
>> instance of BORON in the table you can find in the manual under
>>
>> 10.4.1.2} List of materials for which cross sections are available in the
>> 260 neutron, 42 gamma group library:
>>
>> ... for which there are no available pointwise cross sections in FLUKA.
>>
>> If you name your boron BORON-10, FLUKA will provide the indeed available
>> low-energy neutron cross sections for 10B at 296 K, which you can check
>> is the first instance of BORON-10 in the table above.
>>
>> For the particular reaction 10B(n,alpha)7Li, pointwise cross sections
>> are automatically activated. Thus, for this particular case there is no
>> need to pass an additional LOW-NEUT card to request pointwise low-energy
>> neutron cross sections.
>>
>> As a result of renaming your boron to BORON-10, and of the fact that
>> pointwise cross sections are automatically active for 10B(n,alpha)7Li,
>> your alphas will be generated and transported, and idem for your 7Li
>> (transported, unless I'm mistaken, thanks to the IONTRANS card you
>> pass).
>>
>> Hoping this was reasonably accurate and helpful,
>>
>> Cesc
>>
>> PS: A few minor coments after a quick look at your input file: I see you
>> explicitly pass an EMF card. Note that since you are using DEFAULTS with
>> PRECISIOn, EMF is already activated anyway (see the manual).
>>
>> PS2: you pass relatively low delta-ray production thresholds (1 keV).
>> Adapt the FUDGEM parameter (fraction of atomic electrons contributing to
>> multiple Coulomb scattering, i.e. WHAT(3) in the EMFCUT card with
>> SDUM=PROD-CUT) accordingly, giving it a relatively low value, say 1e-5.
>>
>>
>> On Mon, Jun 04 2018, at 15:07 +0800, YANG Tao wrote:
>> >
>> >Dear FLUKA users,
>> >
>> > Recently I am research the energy spectrum of B(n,α)Li reaction, I use USRBDX card to score the energy spectrum of α and Li, but unfortunately I get nothing. I have switch on ion transportation(IONTRANS card). Maybe just I don't know how to set the relevant card, such as PHYSICS and IONTRANS card. Could anyone help me to point out the mistakes? Attachment is the input file. Any suggestion is appreciated!
>> >
>> >Best regards!
>> >
>> >Yang
>> >
>> >
>>
>>
>>
>> --
>> Francesc Salvat Pujol
>> CERN-EN/STI
>> CH-1211 Geneva 23
>> Switzerland
>> Tel: +41 22 76 64011
>> Fax: +41 22 76 69474
>>
>> __________________________________________________________________________
>> You can manage unsubscription from this mailing list at https://www.fluka.org/fluka.php?id=acc_info
>
>
>






--
Francesc Salvat Pujol
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
Tel: +41 22 76 64011
Fax: +41 22 76 69474
__________________________________________________________________________
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Received on Fri Jun 08 2018 - 19:17:46 CEST

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