Program - Brookhaven National Laboratory

analysis of neutron leakage spectrum of some LLNL pulsed sphere facilities. The SENS1D results shown a
good agreement with other S/U codes mentioned above, while duo to the difference of covariance data, the
uncertainty results by nuclei and reaction shows a little bit difference. As part of SENS package of CNDC,
SENS1D is still under development, to which the ability for the S/U analysis of more reactions and more
aiming integral parameters will be added in the near future.
Session DF Neutron Cross Section Measurements
Monday March 4, 2013
Room: Central Park East at 3:30 PM
DF 1 3:30 PM
Measurement and Analysis of Gamma-ray Cross Sections
Richard B. Firestone, M.S. Basunia, A.M. Hurst, A.M. Rogers, Lawrence Berkeley National Laboratory,
Berkeley, CA 94720. K. Abusaleem, Jordan Atomic Energy Commission, Amman, Jordan. F. Becvar, M.
Krticka, Charles University in Prague, Faculty of Mathematics and Physics, Czech Republic. T. Belgya,
L. Szentmiklosi, Centre for Energy Research, Hungarian Academy of Sciences, Budapest Hungary. L.A.
Bernstein, J.E. Escher, B. Sleaford, N.C. Summers, Lawrence Livermore National Laboratory, Livermore,
CA 94551. H.D. Choi, Seoul National University, Korea. Zs. Revay, Forschungneutronquelle Heinz
Maier-Leibnitz (FRM II), Technische Univsersitat, Munich Germany.
We have measured prompt and delayed thermal neutron-capture γ-ray cross sections on all stable elemental
targets and selected enriched isotopic and radioactive targets with guided neutron beams from the Budapest
and Munich Reactors. These data are maintained in the LBNL/IAEA Evaluated Gamma-ray Activation
File (EGAF). The first version of EGAF data analysis is now complete and available at http://wwwnds.iaea.org/pgaa/tecdoc.pdf.
We have begun a new effort to expand EGAF and exploit the richness
of this database for determining additional quantities important to both the nuclear data and physics
communities. Total radiative thermal neutron cross sections, σγ, are determined from the neutron-capture
γ-ray decay schemes supplemented with statistical model calculations of continuum contributions using the
Monte Carlo code DICEBOX developed at Charles University in Prague. The calculations require reliable
nuclear structure information, typically available in the Evaluated Nuclear Structure Data File (ENSDF).
Our analysis improves the ENSDF file by using the EGAF data and detailed statistical model calculations.
The newly evaluated nuclear structure data can then be included in both the ENSDF and Reaction Input
Parameter Library (RIPL) files. The EGAF database also provides valuable model-independent information
on the photon strength functions (PSFs) for primary gamma transitions and constraints on PSFs for
low-energy transitions to-, from- and between nuclear levels in the quasicontinuum. The PSFs form an
important ingredient of statistical model calculations. Nevertheless, reliable data on them in wide-enough
energy region are still scarce. Both prompt and delayed γ-rays are measured simultaneously in our experiments,
so we can determine the γ-ray transition probabilities Pγ=σγ/σ0 necessary to normalize the decay
schemes of activation products. New evaluations of activation decay data will be provided to the Decay
Data Evaluation Project (DDEP). Our measurements also include precise determinations of primary γ-ray
energies allowing us to provide precise neutron separation energies, Sn, to the Atomic Mass Data Center.
In this paper we will discuss the recent progress that we have made measuring and evaluating EGAF data
and our plans for disseminating this information to the nuclear science and engineering communities. This
work was performed under Contracts No. DE-AC02-05CH11231 and DE-AC52-07NA27344 with the U.S.
Department of Energy, and supported by NAP VENEUS OMFB 00184/2006.
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