Search for the ${}^{15}$Be ground state

Search for the $^{15}$ Be ground state

A. Spyrou, J. K. Smith, T. Baumann, B. A. Brown, J. Brown, G. Christian, P. A. DeYoung, N. Frank, S. Mosby, W. A. Peters, A. Schiller, M. J. Strongman, M. Thoennessen, and J. A. Tostevin

Phys. Rev. C 84, 044309 – Published 12 October 2011

Abstract

A two-proton knockout reaction from a $^{17}$ C beam at 55 MeV/u was used to produce the unbound nucleus $^{15}$ Be. No significant number of events were observed for the decay of $^{15}$ Be into a neutron and a $^{14}$ Be fragment. An upper limit for the $^{14}$ Be production cross section of 0.079 $\pm$ 0.038 mb was extracted, which is more than an order of magnitude smaller than the predicted two-proton knockout reaction cross section. Based on these results we conclude that any populated states in $^{15}$ Be decay through three sequential neutron decays into $^{12}$ Be, via the unbound first excited state of $^{14}$ Be. Therefore, these states in $^{15}$ Be must be neutron unbound by more than 1.54 MeV, which is the location of the first excited 2 $^{+}$ state in $^{14}$ Be.

Received 1 July 2011

DOI:https://doi.org/10.1103/PhysRevC.84.044309

Authors & Affiliations

A. Spyrou^1,2,*, J. K. Smith^1,2, T. Baumann¹, B. A. Brown^1,2, J. Brown³, G. Christian^1,2, P. A. DeYoung⁴, N. Frank⁵, S. Mosby^1,2, W. A. Peters^6,†, A. Schiller⁷, M. J. Strongman¹, M. Thoennessen^1,2, and J. A. Tostevin⁸

¹National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
²Department of Physics & Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
³Department of Physics, Wabash College, Crawfordsville, Indiana 47933, USA
⁴Department of Physics, Hope College, Holland, Michigan 49423, USA
⁵Department of Physics & Astronomy, Augustana College, Rock Island, Illinois, 61201, USA
⁶Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
⁷Department of Physics & Astronomy, Ohio University, Athens, Ohio 45701, USA
⁸Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom

^*spyrou@nscl.msu.edu
^†Present Address: Oak Ridge Associated Universities, Oak Ridge, TN 37830, USA.

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Vol. 84, Iss. 4 — October 2011

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