Program - Brookhaven National Laboratory

Jagiellonian University, Reymonta 4, 30059 Krakow, Poland. K. Pysz, H. Niewodniczanski Institute of
Nuclear Physics PAN, Radzikowskiego 152, 31342 Krakow, Poland. Z. Rudy, Smoluchowski Institute of
Physics, Jagiellonian University, Reymonta 4, 30059 Krakow, Poland. R. Siudak, H. Niewodniczanski
Institute of Nuclear Physics PAN, Radzikowskiego 152, 31342 Krakow, Poland. M. Wojciechowski,
Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30059 Krakow, Poland.
Calculations were done for proton induced spallation reactions over wide range of atomic masses of the
targets; 12 C, 27 Al, Ni, Ag, and 197 Au using an Intra-nuclear Cascade Model (INCL 4.3) with coalescence
which includes the emission of light clusters (d - 4 He) formed by the nucleons during first stage of reaction.
The evaporation process of various particles from excited cascade residua were described using the code
GEM(2.0). A comparison of calculations with experimental double differential cross sections dσ/dΩ dE for
light charged particles ( 1 H, 2 H, 3 H, 3 He, 4 He) obtained by PISA collaboration was studied at proton beam
energy 1.9 GeV. Systematic deviations of theoretical spectra from the experimental data were observed.
These deviations are most pronounced at forward scattering angles and at higher energies of ejectiles. This
situation points to the need to check the shortcomings of used parametrization and lacking of some important
physical processes which are not taken under consideration in models. This work was supported by
the Foundation for Polish Science MPD program, cofinanced by the European Union within the European
Regional Development Fund.
PR 117
Monte Carlo Predictions of Prompt Fission Neutrons and Gamma Rays: a Code
Comparison
P. Talou, T. Kawano, I. Stetcu, Nuclear Physics Group, Theoretical Division, Los Alamos National
Laboratory, Los Alamos, NM 87545, USA. R. Vogt, Physics Division, Lawrence Livermore National
Laboratory, Livermore, CA 94551, USA and Physics Department, University of California, Davis, CA
95616, USA. J. Randrup, Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley,
CA 94720, USA.
In recent years, Monte Carlo techniques have been implemented successfully to predict prompt fission
neutron and gamma-ray data, calculate average quantities such as the average prompt fission neutron
spectrum and multiplicity, as well as distributions such as the neutron multiplicity distribution P (ν) and
correlations, e.g., n-n energy and angular correlations. Several codes are being developed worldwide to
perform such calculations. At LANL, the CGMF code implements in full the Hauser-Feshbach formalism
that describes the statistical de-excitation of the primary fission fragments by the emission of neutrons and
gamma rays. CGMF combines two previously developed codes, the CGM Hauser-Feshbach code [1] and the
FFD code [2] that describes the initial conditions of the fission fragment yields in mass, charge and kinetic
energy, and the initial distribution of excitation energies and spins of the fragments. At LBNL and LLNL,
the FREYA code [3,4] has been developed in the last few years. It simulates the emission of prompt neutrons
from a Weisskopf-Ewing spectrum, following in detail the sequence of neutron emissions until it reaches a
lower energy limit below which only gamma rays can be emitted. Also, recent efforts have been put into
modeling the prompt gamma-ray emissions into FREYA [5]. Both codes use very similar, although distinct,
physics models as well as input parameters. In this work, we present an inter-comparison of the FREYA
and CGMF codes by studying their results predicted for the neutron-induced fission reaction of 239 Pu. In
particular, we focus on differing physical assumptions, e.g., the partitioning of excitation energy between
the two fragments, Hauser-Feshbach vs. Weisskopf-Ewing, etc., and how they impact the final results.
[1] T. Kawano, P. Talou, M.B. Chadwick, and T. Watanabe, J. Nucl. Sci. Tech. 47 (5), 462 (2010). [2]
P. Talou, B. Becker, T. Kawano, M.B. Chadwick, and Y. Danon, Phys. Rev. C 83, 064612 (2011). [3] J.
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