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Title: Total absorption spectroscopy study of the β decay of Br 86 and Rb 91

Abstract

The beta decays of Br-86 and Rb-91 have been studied using the total absorption spectroscopy technique. The radioactive nuclei were produced at the Ion Guide Isotope Separator On-Line facility in Jyvaskyla and further purified using the JYFLTRAP. Br-86 and Rb-91 are considered to be major contributors to the decay heat in reactors. In addition, Rb-91 was used as a normalization point in direct measurements of mean gamma energies released in the beta decay of fission products by Rudstam et al. assuming that this decaywas well known from high-resolution measurements. Our results show that both decays were suffering from the Pandemonium effect and that the results of Rudstam et al. should be renormalized. The relative impact of the studied decays in the prediction of the decay heat and antineutrino spectrum from reactors has been evaluated.

Authors:
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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Nuclear Physics; Spanish Ministerio de Economia y Competitividad (MINECO); Engineering and Physical Sciences Research Council (EPSRC); STFC Daresbury Laboratory
OSTI Identifier:
1376708
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C; Journal Volume: 96; Journal Issue: 1
Country of Publication:
United States
Language:
English

Citation Formats

Rice, S., Algora, A., Tain, J. L., Valencia, E., Agramunt, J., Rubio, B., Gelletly, W., Regan, P. H., Zakari-Issoufou, A. -A., Fallot, M., Porta, A., Rissanen, J., Eronen, T., Äystö, J., Batist, L., Bowry, M., Bui, V. M., Caballero-Folch, R., Cano-Ott, D., Elomaa, V. -V., Estevez, E., Farrelly, G. F., Garcia, A. R., Gomez-Hornillos, B., Gorlychev, V., Hakala, J., Jordan, M. D., Jokinen, A., Kolhinen, V. S., Kondev, F. G., Martínez, T., Mason, P., Mendoza, E., Moore, I., Penttilä, H., Podolyák, Zs., Reponen, M., Sonnenschein, V., Sonzogni, A. A., and Sarriguren, P. Total absorption spectroscopy study of the β decay of Br86 and Rb91. United States: N. p., 2017. Web. doi:10.1103/PhysRevC.96.014320.
Rice, S., Algora, A., Tain, J. L., Valencia, E., Agramunt, J., Rubio, B., Gelletly, W., Regan, P. H., Zakari-Issoufou, A. -A., Fallot, M., Porta, A., Rissanen, J., Eronen, T., Äystö, J., Batist, L., Bowry, M., Bui, V. M., Caballero-Folch, R., Cano-Ott, D., Elomaa, V. -V., Estevez, E., Farrelly, G. F., Garcia, A. R., Gomez-Hornillos, B., Gorlychev, V., Hakala, J., Jordan, M. D., Jokinen, A., Kolhinen, V. S., Kondev, F. G., Martínez, T., Mason, P., Mendoza, E., Moore, I., Penttilä, H., Podolyák, Zs., Reponen, M., Sonnenschein, V., Sonzogni, A. A., & Sarriguren, P. Total absorption spectroscopy study of the β decay of Br86 and Rb91. United States. doi:10.1103/PhysRevC.96.014320.
Rice, S., Algora, A., Tain, J. L., Valencia, E., Agramunt, J., Rubio, B., Gelletly, W., Regan, P. H., Zakari-Issoufou, A. -A., Fallot, M., Porta, A., Rissanen, J., Eronen, T., Äystö, J., Batist, L., Bowry, M., Bui, V. M., Caballero-Folch, R., Cano-Ott, D., Elomaa, V. -V., Estevez, E., Farrelly, G. F., Garcia, A. R., Gomez-Hornillos, B., Gorlychev, V., Hakala, J., Jordan, M. D., Jokinen, A., Kolhinen, V. S., Kondev, F. G., Martínez, T., Mason, P., Mendoza, E., Moore, I., Penttilä, H., Podolyák, Zs., Reponen, M., Sonnenschein, V., Sonzogni, A. A., and Sarriguren, P. Sat . "Total absorption spectroscopy study of the β decay of Br86 and Rb91". United States. doi:10.1103/PhysRevC.96.014320.
@article{osti_1376708,
title = {Total absorption spectroscopy study of the β decay of Br86 and Rb91},
author = {Rice, S. and Algora, A. and Tain, J. L. and Valencia, E. and Agramunt, J. and Rubio, B. and Gelletly, W. and Regan, P. H. and Zakari-Issoufou, A. -A. and Fallot, M. and Porta, A. and Rissanen, J. and Eronen, T. and Äystö, J. and Batist, L. and Bowry, M. and Bui, V. M. and Caballero-Folch, R. and Cano-Ott, D. and Elomaa, V. -V. and Estevez, E. and Farrelly, G. F. and Garcia, A. R. and Gomez-Hornillos, B. and Gorlychev, V. and Hakala, J. and Jordan, M. D. and Jokinen, A. and Kolhinen, V. S. and Kondev, F. G. and Martínez, T. and Mason, P. and Mendoza, E. and Moore, I. and Penttilä, H. and Podolyák, Zs. and Reponen, M. and Sonnenschein, V. and Sonzogni, A. A. and Sarriguren, P.},
abstractNote = {The beta decays of Br-86 and Rb-91 have been studied using the total absorption spectroscopy technique. The radioactive nuclei were produced at the Ion Guide Isotope Separator On-Line facility in Jyvaskyla and further purified using the JYFLTRAP. Br-86 and Rb-91 are considered to be major contributors to the decay heat in reactors. In addition, Rb-91 was used as a normalization point in direct measurements of mean gamma energies released in the beta decay of fission products by Rudstam et al. assuming that this decaywas well known from high-resolution measurements. Our results show that both decays were suffering from the Pandemonium effect and that the results of Rudstam et al. should be renormalized. The relative impact of the studied decays in the prediction of the decay heat and antineutrino spectrum from reactors has been evaluated.},
doi = {10.1103/PhysRevC.96.014320},
journal = {Physical Review C},
number = 1,
volume = 96,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}
  • We investigate the decay of Br-87,Br-88 and Rb-94 using total absorption gamma-ray spectroscopy. These important fission products are beta-delayed neutron emitters. Our data show considerable beta gamma intensity, so far unobserved in high-resolution gamma-ray spectroscopy, from states at high excitation energy. We also find significant differences with the beta intensity that can be deduced from existing measurements of the beta spectrum. We evaluate the impact of the present data on reactor decay heat using summation calculations. Although the effect is relatively small it helps to reduce the discrepancy between calculations and integral measurements of the photon component for U-235 fissionmore » at cooling times in the range 1-100 s. We also use summation calculations to evaluate the impact of present data on reactor antineutrino spectra. We find a significant effect at antineutrino energies in the range of 5 to 9 MeV. In addition, we observe an unexpected strong probability for. emission from neutron unbound states populated in the daughter nucleus. The. branching is compared to Hauser-Feshbach calculations, which allow one to explain the large value for bromine isotopes as due to nuclear structure. However the branching for Rb-94, although much smaller, hints of the need to increase the radiative width gamma by one order of magnitude. This increase in gamma would lead to a similar increase in the calculated (n, gamma) cross section for this very neutron-rich nucleus with a potential impact on r process abundance calculations.« less
  • Cited by 4
  • In this paper, we investigate the decay of 87,88Br and 94Rb using total absorption γ-ray spectroscopy. These important fission products are β-delayed neutron emitters. Our data show considerable βγ intensity, so far unobserved in high-resolution γ-ray spectroscopy, from states at high excitation energy. We also find significant differences with the β intensity that can be deduced from existing measurements of the β spectrum. We evaluate the impact of the present data on reactor decay heat using summation calculations. Although the effect is relatively small it helps to reduce the discrepancy between calculations and integral measurements of the photon component formore » 235U fission at cooling times in the range 1-100 s. We also use summation calculations to evaluate the impact of present data on reactor antineutrino spectra. We find a significant effect at antineutrino energies in the range of 5 to 9 MeV. In addition, we observe an unexpected strong probability for γ emission from neutron unbound states populated in the daughter nucleus. The γ branching is compared to Hauser-Feshbach calculations, which allow one to explain the large value for bromine isotopes as due to nuclear structure. However the branching for 94Rb, although much smaller, hints of the need to increase the radiative width Γ γ by one order of magnitude. Finally, this increase in Γ γ would lead to a similar increase in the calculated (n, γ) cross section for this very neutron-rich nucleus with a potential impact on r process abundance calculations.« less