States inviadecay of
Authors:
- C. S. SumithrarachchiCSC. S. Sumithrarachchi
- D. J. MorrisseyDMD. J. Morrissey
- A. D. DaviesADA. D. Davies
- D. A. DaviesDDD. A. Davies
- M. FacinaMFM. Facina
- E. KwanEKE. Kwan
- P. F. ManticaPMP. F. Mantica
- M. PortilloMPM. Portillo
- Y. ShimbaraYSY. Shimbara
- J. StokerJSJ. Stoker
- R. R. WeerasiriRWR. R. Weerasiri
- 8 January 2010
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review C
- Vol. 81 (1)
Abstract
The energy-level structure of O22 with the recently identified N=14 subshell closure was investigated by the $\beta${} decay of N22 for the first time. A $\beta${}-delayed-neutron, time-of-flight measurement revealed six new neutron transitions attributed to the $\beta${} decay of N22. One- and two-$\beta${}-delayed neutron decay of N22, with emission probabilities of 33(3)% and 12(3)%, respectively, were observed to correspond to four new negative-parity states in O22. The half-life of N22 $\beta${} decay was determined to be 20(2) ms. Three $\gamma${}-ray transitions in O22 and single $\gamma${}~rays in O21 and O20 were observed following the $\beta${} decay of N22. The observation of large Gamow-Teller strength for a highly excited state in O22 indicates a halo structure for N22. A comparison of results with shell-model predictions showed overall poor agreement. The measured Pn values of O24 and F25 components of the secondary beam showed an enhancement relative to the Pn values of adjacent oxygen and fluorine isotopes, providing additional evidence for the N=14 closed subshell.Keywords
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