Program - Brookhaven National Laboratory

DF 5 5:00 PM
Determination of the 151 Eu(n,γ) 152m1,g Eu and 153 Eu(n,γ) 154 Eu Reaction Cross Sections at
Thermal Neutron Energy*
M.S. Basunia, R.B. Firestone, E. Browne, A.M. Hurst, Lawrence Berkeley National Laboratory, Berkeley,
CA 94720. T. Belgya, L. Szentmiklosi, Centre for Energy Research, HAS, Budapest, Hungary. H. Choi,
Seoul National University, Korea. J.E. Escher, B. Sleaford, N.C. Summers, Lawrence Livermore National
Laboratory, Livermore, CA 94551. M. Krtika, Charles University in Prague, Czech Republic. Zs. Revay,
Technische Universität, Munich, Germany.
We have measured partial γ-ray cross sections following neutron capture in enriched targets of 151 Eu and
153 Eu at the cold neutron beam facility of the Budapest Neutron Center using a Compton-suppressed
HPGe and a LEPS detector. These cross sections have been measured at thermal-neutron energy, corrected
for the effective g-factor, and relative to the partial neutron-capture cross section of 2991 ± 60
barns for the 89.8-keV transition in 151 Eu. This partial cross section has been obtained by irradiating a
europium oxide (Eu2O3) solution in 20% H2SO4 and relative to the cross section of 0.3326 ± 0.0007 barns
for the 2223-keV transition from thermal neutron capture in 1 H. The total radiative capture cross sections
of the 151 Eu(n,γ) 152m1,g Eu and 153 Eu(n,γ) 154 Eu reactions were determined by combining experimental
data with theoretical modeling of the γ-ray cascade: calculated intensities (using the DICEBOX Monte
Carlo statistical code) for transitions from the continuum region were added to the measured transition
intensities from known levels to the ground- or metastable-state. The individual 151 Eu(n,γ) 152m1 Eu and
151 Eu(n,γ) 152g Eu reaction cross sections are found to be in disagreement with the recommended value by
Mughabghab 1 . However, the total cross section of the 151 Eu(n,γ) 152m1+g Eu reaction is in good agreement.
Also, our determined cross section for the 153 Eu(n,γ) 154 Eu reaction is in good agreement with the recommended
value. In the course of this work, the gamma decay schemes for the low-energy levels in 152 Eu
and 154 Eu have been verified and evaluated. Another standardization measurement of the partial neutron
capture cross section for the 89.8-keV transition using a stoichiometric compound of europium in solid
form is in progress. This measurement will be useful for a better estimation of the effective g-factor and
verification of the measured cross sections as well.
[1] S.F. Mughabghab - Atlas of Neutron Resonances, 5th edition, Resonance Parameters and Thermal
Cross Sections, Z = 1-100, Elsevier, Amsterdam (2006) * 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
DF 6 5:15 PM
New Measurement of the Thermal-Capture Cross Section for the Minor Isotope 180 W
A. M. Hurst, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. R. B. Firestone,
Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. B. W. Sleaford, Lawrence Livermore
National Laboratory, Livermore, CA 94551, USA. N. C. Summers, Lawrence Livermore National
Laboratory, Livermore, CA 94551, USA. Zs. Revay, Centre for Energy Research, Hungarian Academy of
Sciences, Budapest, Hungary. L. Szentmiklosi, Centre for Energy Research, Hungarian Academy of
Sciences, Budapest, Hungary. M. S. Basunia, Lawrence Berkeley National Laboratory, Berkeley, CA
94720, USA. T. Belgya, Centre for Energy Research, Hungarian Academy of Sciences, Budapest,
Hungary. J. E. Escher, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA. M.
Krticka, Charles University in Prague, Faculty of Mathematics and Physics, Prague, Czech Republic.
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