β-delayed neutron decay of N19 and N20

C. S. Sumithrarachchi, D. W. Anthony, P. A. Lofy, and D. J. Morrissey
Phys. Rev. C 74, 024322 – Published 28 August 2006

Abstract

The results of the first spectroscopic studies of delayed neutron and γ emission following the β decay of N19 and N20 are reported. Nuclides were produced by fragmenting an 80 MeV/nucleon Ne22 beam in a 546 mg/cm2 thick Be target and were separated at high velocities with the A1200 fragment separator. The nuclides were implanted in a thin plastic scintillator at the center of an array of neutron scintillators to determine the neutron time-of-flight spectrum. Two hyperpure germanium detectors were used to observe coincident γ events. The β–γ,βn, and β–n–γ coincidence spectra were analyzed to obtain the energies of the states populated in O18, O19, and O20 following the β decay. Eight new neutron energies with a total neutron emission probability of 41.8(9)%, six γ transitions among the excited states of O19, and four γ transitions among the excited states of O18 were identified in the N19 β decay. Seven new neutron energies with a total neutron emission probability of 42.9(14)%, ten γ transitions among the excited states of O20, and two γ transitions among the exited states of O19 were observed from the N20 β decay. Half-lives of 336(3) and 136(3) ms were determined for the N19 and N20 decays, respectively. The branching ratios of both decays were deduced and compared with USD (universal sd-shell) shell model calculations. The β decay schemes for N19 and N20 were deduced.

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  • Received 9 May 2006

DOI:https://doi.org/10.1103/PhysRevC.74.024322

©2006 American Physical Society

Authors & Affiliations

C. S. Sumithrarachchi*, D. W. Anthony, P. A. Lofy, and D. J. Morrissey

  • National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA

  • *Electronic address: chandana@nscl.msu.edu
  • New address: Fifth U.S. Army, CSRD, Fort Sam, Houston, TX 78234.

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Issue

Vol. 74, Iss. 2 — August 2006

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