Program - Brookhaven National Laboratory

purity of the sources. A brief summary of the latest results of the measurements using a new segmented
total absorption spectrometer, the faced challenges depending of the particular nuclei as well as new developments
of the techniques of analysis will be discussed. The impact of the measurements on summation
calculations of the decay heat in reactors and in nuclear structure will be addressed [2,3,4]. Future plans
and the development of a new modular TAS detector (DTAS) for the DEcay SPECtroscopy (DESPEC)
experiment at FAIR will also be presented.
[1] A. Algora et al., Phys. Rev. Letts. 105 (2010) 202501 [2] A. Petrovici private communication [3] K-L.
Kratz, private communication [4] A. Sonzogni, private communication
DD 2 4:00 PM
First Results from the Modular Total Absorption Spectrometer at the HRIBF (ORNL,
Oak Ridge)*
M. Karny, Faculty of Physics, University of Warsaw, Warsaw, Poland; ORNL, Oak Ridge, USA; ORAU,
Oak Ridge, USA. A. Fijalkowska, Faculty of Physics, University of Warsaw, Warsaw, Poland; University
of Tennessee, Knoxville, USA. K.P. Rykaczewski, ORNL, Oak Ridge, USA. M. Wolińska-Cichocka,
ORNL, Oak Ridge, USA; ORAU, Oak Ridge, USA. B.C. Rasco, Louisiana State University, Baton
Rouge, USA. C.J. Gross, ORNL, Oak Ridge, USA. R.K. Grzywacz, University of Tennessee, Knoxville,
USA; ORNL, Oak Ridge, USA. L. Cartegni, University of Tennessee, Knoxville, USA. R. Goans, ORNL,
Oak Ridge, USA. K.C. Goetz, University of Tennessee, Knoxville, USA. J. W. Johnson, ORNL, Oak
Ridge, USA. J.H. Hamilton, Dept. of Physics and Astronomy, Vanderbilt University, Nashville, USA. C.
Jost, ORAU, Oak Ridge, USA. M. Madurga, University of Tennessee, Knoxville, USA. K. Miernik,
Faculty of Physics, University of Warsaw, Warsaw, Poland; ORNL, Oak Ridge, USA. D. Miller,
University of Tennessee, Knoxville, USA. S.W. Padgett, University of Tennessee, Knoxville, USA. S.V.
Paulauskas, University of Tennessee, Knoxville, USA. A.V. Ramayya, Dept. of Physics and Astronomy,
Vanderbilt University, Nashville, USA. M. Al-Shudifat, University of Tennessee, Knoxville, USA. E.
Spejewski, ORAU, Oak Ridge, USA. D. Stracener, ORNL, Oak Ridge, USA. E. Zganjar, Louisiana State
University, Baton Rouge, USA.
Total Absorption Spectrometers (TAS) capable of detecting most of the gamma transitions occurring during
the decay process are perfect tools for establishing a true beta feeding pattern. TAS-aided experiments are
particularly important for neutron-rich nuclei, where the beta strength is highly distributed over many final
states. Knowledge of the correct beta feeding pattern is important for the analysis of the structure of parent
and daughter activities as well as for the determination of the decay heat released by fission products during
nuclear fuel cycle. The Modular Total Absorption Spectrometer (MTAS) has been recently constructed
at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. It consists of
19 NaI(Tl) hexagonal shape modules, with a full energy gamma ray efficiency approaching 90% around
300 keV [1]. The decays of over twenty 238 U fission products have been studied with MTAS during the
first online experiment at the HRIBF. Already online data for some isotopes show significant discrepancy
between the observed beta feeding and the corresponding database values. In this contribution the first
results for nuclei with mass ranging from 86 to 90, including 86,87 Br, 89,90 Kr, will be presented. The impact
of this new data on the decay heat calculation will be discussed as well. ∗ This work was supported by the
U.S. Department of Energy Office of Nuclear Physics.
[1] M. Wolińska-Cichocka et al., ”Modular total Absorption Spectrometer at HRIBF”, this conference
DD 3 4:20 PM
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