Monte Carlo calculations of nucleon-induced fission in the GeV energy range

Sergio Lo Meo,Cristian Massimi,Gianni Vannini,Alberto Ventura,Davide Mancusi,Diego Tarrio,A Plompen,W Mondelaers,P Siegler,J Heyse,F.-J Hambsch,S Oberstedt,P Schillebeeckx,S Kopecky

doi:10.1051/epjconf/201714604049

Sergio Lo Meo, Cristian Massimi + Show 12 more

Open Access

https://doi.org/10.1051/epjconf/201714604049

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Abstract

In the present work the Monte Carlo calculations of nucleon-induced fission on actinides and pre-actinides from 100 MeV to 1 GeV, described in a recent paper of ours [1], are extended up to an incident energy of 8 GeV. The calculated (p,f) cross sections are compared with the few experimental data available in the literature. The same model parameters are used to predict (n,f) cross sections in the same energy range. Possible shortcomings of decay models at high incident energies are discussed.

Highlights

In this work use is made of version 5.2 [3] of INCL++, including multiple pion production as described in Ref. [4], and allowing calculations up to 10–12 GeV, while version 5.1.14 adopted in our previous work [1] described only single pion production from the decay of delta resonances; the versions of the evaporationfission models yielding fission cross sections, GEMINI++ [5] and ABLA07 [6], are the same as in Ref. [1], so that the changes of input parameters and of numerical results below 1 GeV are entirely connected with the new version of the fast cascade model
Following the philosophy of the authors of INCL++, as we already did in Ref. [1], no parameters have been modified in the intranuclear cascade model, already optimized by reproducing a large amount of data connected with the cascade stage, while two basic fission parameters have been taken as adjustable in the decay models, i.e. the asymptotic level density parameter of the fission channel, a f, multiplied by a factor k in ABLA07, or the ratio of a f to the level density parameter of the neutron channel, an, in GEMINI++, where the default value is a f /an = 1.036, and the height of the fission barriers, B f of the remnants, that can be reduced, or increased by the same amount, B f
The behaviour of calculated pre-actinide cross sections in the GeV energy range deserves discussion: a clue might be given by the average excitation energy of the remnants undergoing fission, or, even better, by their average excitation energy per nucleon as a function of incident energy, shown in Fig. 5 for the INCL++/GEMINI++ calculation of the ( p, f ) cross section of 238U on the left panel and 181T a on the right panel; the statistics used to estimate average values and root-mean-square deviations are limited to fission events in the incident energy range from 100 MeV to 10 GeV

Summary

Introduction

[4], and allowing calculations up to 10–12 GeV, while version 5.1.14 adopted in our previous work [1] described only single pion production from the decay of delta resonances; the versions of the evaporationfission models yielding fission cross sections, GEMINI++ [5] and ABLA07 [6], are the same as in Ref.

Results

Conclusion