Effects of the Serber First Step in 3DHZETRN-v2.1

Wilson, John W ; Werneth, Charles M ; Slaba, Tony C ; Badavi, Francis F ; Reddell, Brandon D ; Bahadori, Amir A ; Sandridge, Christopher A [Editor] ; Blattnig, Steve R [Editor] ; Norman, Ryan B [Editor]

关键词: NUMERICAL ANALYSIS;    COMPUTER PROGRAMS;    CONSERVATION EQUATIONS;    LIGHT IONS;    FLUENCE;    ABSORPTION CROSS SECTIONS;    SCATTERING CROSS SECTIONS;    NUCLEON-NUCLEON SCATTERING;    NUCLEAR MODELS;    DYNAMIC MODELS;    EXTRATERRESTRIAL RADIATION;   

RP-ID  :  NASA/TP-2019-220401,L-21054,NF1676L-34294

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来源: NASA Technical Reports Server

【 摘 要 】

3DHZETRN-v2 includes a detailed three dimensional (3D) treatment of neutron/light-ion transport based on a quasi-elastic/multiple-production assumption allowing improved agreement of the neutron/light-ion fluence compared with results of three Monte Carlo (MC) codes in the sense that the variance with respect to the individual MC results is less than the variance among the MC code results. The current numerical methods are no longer the main limitation to HZETRN code development and further changes in the nuclear model are required. In a prior study, an improved quasi-elastic spectrum based on a solution of the transport approximation to nuclear media effects showed promise, but the remaining multiple-production spectrum was based on a database derived from the Ranft model that used Bertini multiplicities. In the present paper, we will implement a more complete Serber first step into the 3DHZETRN-v2 code, but we retain the Bertini-Ranft branching ratios and evaporation multiplicities. It is shown that the new Serber model in the 3HZETRN-v2 code reduces the variance with individual MC codes, which are largely due to nuclear cross section model differences.