${ }^{8}Be$ Anomalous Internal Pair Production: Possible E2 Transitions .

ORAL

Abstract

Significant enhancement of ${ }^{8}Be$ internal pair production at 16.7 MeV with large angle correlations from the 18.150 MeV ($J^{\pi }=1^{+})$ level have been interpreted as a possible dark matter candidate, a light ($J^{\pi }=1^{+})$ neutral boson [PRL \underline {116}\textbf{(}2016)042501] or a fifth-force vector gauge boson [PRL \underline {117}(2016)071803]. We present a conventional alternative interpretation, unseen E2 transitions from the $J^{\pi }=2^{+}$levels at 16.626 MeV and 16.922 MeV populated in the decay of the 18.150 MeV ($J^{\pi }=1^{+})$ level. The calculated E2 transition probabilities agree well with the measured pair production intensity in the back angle correlation where one expects the E2 gamma-ray correlation to peak. .

Authors

  • Thomas Ward

    U.S. Department of Energy, Office of Nuclear Energy, Germantown, Maryland 20874

  • David Koltick

    Purdue University, Department of Physics, Purdue University, West Layfacette, IN47906

  • Haoyu Wang

    Department of Physics, Purdue University, West Layfacette, IN47906