[fluka-discuss]: Low energy (p,n) reactions with light nuclei

From: <Jack.McKinney_at_stfc.ac.uk>
Date: Wed, 11 Sep 2019 14:30:44 +0000

Dear all,

I am running simulations which involve a proton beam (broad energy spectrum between 1 MeV and 30 MeV) incident on a block of natural lithium. I am measuring the neutron fluence produced in the forward direction (same direction as proton beam, behind the lithium target) with USRTRACK and USRBDX detectors. My question is related to the modelling performed by FLUKA with regards to the key Li-7(p,n_0)Be-7 reaction and the several ensuing threshold reactions such as the 1st excited residual Li-7(p,n_1)Be-7* and the three body breakup Li-7(p,n+He-3)He-4. I am also interested in the Be-9(p,n)B-9 reaction.

I have searched the Fluka discuss archive and I have read the http://www.fluka.org/web_archive/earchive/new-fluka-discuss/8981.html chain. I have also read several presentations from the Fluka workshops related to the physics models. I have not been able to find specific documentation related to Li-7(p,n)Be-7 reaction, or light nuclei (p,n) reactions in general and their associated issues, despite the reference to them in the linked discussion.

As I understand it, there is no specific model for the Li-7(p,n)Be-7 reaction outside of the standard PEANUT algorithm, and according to the discussion above, the PEANUT modelling includes some rather coarse assumptions which prevent accurate simulations of the Li-7(p,n)Be-7 reaction and (I assume) low energy hadron interactions with light nuclei in general. By low energy I mean <50 MeV and light nuclei A<=15.

* For Li-7 reaction, does the modelling go as: 1) Generalised intra-nuclear cascade for initial interaction 2) Pre-equilibrium emission 3) Equilibrium emission via Fermi breakup 4) Gamma de-excitation ?

* Is there any documentation available about how PEANUT models low energy hadron + light nuclei interactions, and where specifically the limitations of these models arise from?

* Fluka uses evaluated nuclear data when possible. On the ENDF database, there is evaluated cross-section data for the Li-7(p,n)Be-7 and Be-9(p,n)B-9 reactions. Is this used by PEANUT? If not, then how are the reactions modelled?

There is reference material for PEANUT available online but the only documentation I have seen is dated from the late 1990's. Surely this is out of date by now since PEANUT has gone through a lot of development since then?

Thank you for taking the time to read this and for any help you can provide.

Jack McKinney

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Received on Wed Sep 11 2019 - 17:30:59 CEST

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