Program - Brookhaven National Laboratory

In an effort to maintain the quality of the neutron cross section standards, an IAEA Data Development
Project was initiated to provide a mechanism for allowing new experimental data and improvements in
evaluation procedure to be used in new evaluations of the neutron standards. This Project has broadened
its range of activities beyond that of the traditional activities related to the cross section standards by
including work on extending the energy ranges of the standards and also “reference data” that are not so
widely used as the standards but can be very useful in the measurements of certain types of cross sections.
Ongoing work in this Project has included the following activities: an update of the experimental data to
be used in cross section standards evaluations, testing of the uncertainties obtained in the international
standards evaluation, a study of different smoothing procedures for standards, improvements in the gold
capture cross section at energies below where it is considered a standard but is used in capture cross
section measurements for astrophysical applications, work on reference prompt gamma-ray production
cross sections for fast neutron-induced reactions, and combining measurements of the 235 U thermal neutron
fission spectrum with the evaluation of the 252 Cf spontaneous fission neutron spectrum with the aim of
deriving an improved 235 U thermal neutron fission spectrum. The work done in each of the activities in
this project will be discussed.
BF 3 11:20 AM
New Evaluation of n+ 63,65 Cu Nuclear Cross Section Data up to 200 MeV Neutron Energy
P. Pereslavtsev, A. Konobeyev, U. Fischer
Association KIT-Euratom, Karlsruhe Institute of Technology (KIT), Institut für Neutronenphysik u.
Reaktortechnik, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen Karlsruhe, Germany
Vladimir Sobes, Luiz Leal
Nuclear Data Group and Critical Safety, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN
37831, USA
New high energy neutron cross section data have been evaluated for the stable copper isotopes 63,65 Cu in
the energy range from 1-10 −11 up to 200 MeV. The new evaluation provides a complete and consistent
set of reaction data as required for the nuclear analyses of existing and planned facilities including various
transport, heating, shielding and radiation damage calculations. An automated procedure developed at
KIT for nuclear data evaluations makes use of nuclear model results and different experimental data,
including differential and relevant integral ones. The TALYS-1.4 computer code is used to generate a
full set of nuclear reaction data for neutron energies from 0.001 to 200 MeV. TALYS includes many
nuclear reaction models that increase it flexibility and enables high quality model calculations starting
from keV to intermediate and high neutron energies. The statistical Hauser-Feshbach theory is applied
for the compound nuclear reactions and the two-component exciton model is used for the description
of the pre-equilibrium reactions. The nuclear level densities are calculated within generalized superfluid
model. The optical model calculations are performed with ECIS-06 code implemented in TALYS making
use of default optical model potentials (OMPs) for neutrons and protons, external OMPs for deuterons
and alphas and newly developed OMPs for tritons and helions. New resonance parameters evaluations for
n+ 63,65 Cu including covariance data were done with the SAMMY code. This evaluation is based on the new
measurements performed at GELINA on enriched isotopic copper samples for the capture cross sections
and on old measurements preformed at the Oak Ridge Electron Linear Accelerator (ORELA) on highly
enriched isotopic copper samples for the neutron transmission. The reaction cross sections obtained with
TALYS calculations were compared against available experimental data. Validated reaction cross-section
data from the European Activation File (EAF-2010) were adopted as far as suitable for the evaluation
in the neutron energy range below 20 MeV. The Kalbach systematics was used for the description of the
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