Search for unbound ${}^{15}\mathrm{Be}$ states in the $3n+{}^{12}\mathrm{Be}$ channel

Journal Article · 28 January 2015 · Physical Review C, Nuclear Physics

DOI: https://doi.org/10.1103/PhysRevC.91.017304 · OSTI ID:1454846

Kuchera, A. N. ^[1]; Spyrou, A. ^[1]; Smith, J. K. ^[1]; Baumann, T. ^[1]; Christian, G. ^[1]; DeYoung, P. A. ^[2]; Finck, J. E. ^[3]; Frank, N. ^[4]; Jones, M. D. ^[1]; Kohley, Z. ^[1]; Mosby, S. ^[1]; Peters, W. A. ^[5]; Thoennessen, M. ^[1]

---

1. Michigan State Univ., East Lansing, MI (United States)
2. Hope College, Holland, MI (United States)
3. Central Michigan Univ., Mount Pleasant, MI (United States)
4. Augustana College, Rock Island, IL (United States)
5. Rutgers Univ., Piscataway, NJ (United States)

Background: Be-15 is expected to have low-lying 3/2(+) and 5/2(+) states. A first search did not find the 3/2(+) [A. Spyrou et al., Phys. Rev. C 84, 044309 (2011)]; however, a resonance in Be-15 was populated in a second attempt and determined to be unbound with respect to Be-14 by 1.8(1) MeV with a tentative spin-parity assignment of 5/2(+) [J. Snyder et al., Phys. Rev. C 88, 031303(R) (2013)]. Purpose: Search for the predicted Be-15 3/2(+) state in the three-neutron decay channel. Method: A two-proton removal reaction from a 55 MeV/u C-17 beam was used to populate neutron-unbound states in Be-15. The two-, three-, and four-body decay energies of the Be-12+ neutron(s) detected in coincidence were reconstructed using invariant mass spectroscopy. Monte Carlo simulations were performed to extract the resonance and decay properties from the observed spectra. Results: The low-energy regions of the decay energy spectra can be described with the first excited unbound state of Be-14 (E-x = 1.54 MeV, E-r = 0.28 MeV). Including a state in Be-15 that decays through the first excited Be-14 state slightly improves the fit at higher energies though the cross section is small. Conclusions: A Be-15 component is not needed to describe the data. If the 3/2(+) state in Be-15 is populated, the decay by three-neutron emission through Be-14 is weak,

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Nuclear Science and Security Consortium
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0000979
• OSTI ID: 1454846
• Journal Information: Physical Review C, Nuclear Physics, Vol. 91, Issue 1; ISSN 0556-2813
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English