Decay studies of the β-delayed neutron emitters Br 87 and Br 88 measured by means of the Modular Total Absorption Spectrometer at ORNL HRIBF

Authors

M. Stepaniuk, University of Warsaw
M. Karny, University of Warsaw
A. Fijałkowska, University of Warsaw
K. P. Rykaczewski, ORNL Physics Division
B. C. Rasco, ORNL Physics Division
R. K. Grzywacz, Oak Ridge National Laboratory
M. Wolińska-Cichocka, Oak Ridge National Laboratory
J. M. Allmond, ORNL Physics Division
J. C. Batchelder, UC Berkeley’s Department of Nuclear Engineering
C. Bingham, The University of Tennessee, Knoxville
J. C. Blackmon, Louisiana State University
N. T. Brewer, Oak Ridge National Laboratory
S. Go, The University of Tennessee, Knoxville
K. C. Goetz, The University of Tennessee, Knoxville
C. J. Gross, ORNL Physics Division
J. Johnson, ORNL Physics Division
C. U. Jost, ORNL Physics Division
J. H. Hamilton, Vanderbilt University
T. T. King, The University of Tennessee, Knoxville
K. Kolos, The University of Tennessee, Knoxville
J. T. Matta, Oak Ridge National Laboratory
K. Miernik, University of Warsaw
M. Madurga, The University of Tennessee, Knoxville
D. Miller, The University of Tennessee, Knoxville
C. D. Nesaraja, ORNL Physics Division
S. Padgett, The University of Tennessee, Knoxville
S. V. Paulauskas, The University of Tennessee, Knoxville
M. M. Rajabali, Tennessee Technological University
D. W. Stracener, ORNL Physics Division
E. H. Spejewski, ORNL Physics Division
S. Taylor, The University of Tennessee, Knoxville
E. H. Wang, Vanderbilt University
J. A. Winger, Mississippi State University

Document Type

Article

Publication Date

11-1-2024

Abstract

The β decays of Br87, Br88, and Kr87 were measured with the Modular Total Absorption Spectrometer (MTAS) at Oak Ridge National Laboratory's Holifield Radioactive Ion Beam Facility (HRIBF). Both bromine isotopes are β-delayed neutron emitters that have large cumulative fission yields and were identified as top-priority cases for total absorption study by the Nuclear Energy Agency in 2007. Our investigations corroborate that the decay schemes of Br87 and Br88 suffer from the so-called pandemonium effect. Unique MTAS properties enable direct neutron measurements. We present MTAS-derived β-delayed neutron spectra, β-delayed neutron emission probabilities of Pn(Br87) =2.36(24)%, and Pn(Br88) =6.4(6)%, and the β-delayed neutron transitions intensity of 4(2)% to the first excited Kr87 state, populated in the β-neutron decay of Br88. Incorporating new data into calculations of the electromagnetic decay heat component emitted during thermal neutron fission of U235 and Pu239 improves agreement with experimental data up to approximately 80 s after fission. The estimation of the nuclear reactor ν¯e flux results in changes of up to 1% in the expected ν¯e interactions with the detector material for U235, U238, Pu239, and Pu241.

Publication Source (Journal or Book title)

Physical Review C

Recommended Citation

Stepaniuk, M., Karny, M., Fijałkowska, A., Rykaczewski, K., Rasco, B., Grzywacz, R., Wolińska-Cichocka, M., Allmond, J., Batchelder, J., Bingham, C., Blackmon, J., Brewer, N., Go, S., Goetz, K., Gross, C., Johnson, J., Jost, C., Hamilton, J., King, T., Kolos, K., Matta, J., Miernik, K., Madurga, M., Miller, D., Nesaraja, C., Padgett, S., Paulauskas, S., Rajabali, M., Stracener, D., Spejewski, E., Taylor, S., Wang, E., & Winger, J. (2024). Decay studies of the β-delayed neutron emitters Br 87 and Br 88 measured by means of the Modular Total Absorption Spectrometer at ORNL HRIBF. Physical Review C, 110 (5) https://doi.org/10.1103/PhysRevC.110.054321