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Title: Localizing the Shape Transition in Neutron-Deficient Selenium

Abstract

Neutron-deficient selenium isotopes are thought to undergo a rapid shape change from a prolate deformation near the line of beta stability towards oblate deformation around the line of $N=Z$. The point at which this shape change occurs is unknown, with inconsistent predictions from available theoretical models. A common feature in the models is the delicate nature of the point of transition, with the introduction of even a modest spin to the system sufficient to change the ordering of the prolate and oblate configurations. In this paper, we present a measurement of the quadrupole moment of the first-excited state in radioactive $$^{72}\mathrm{Se}$$—a potential point of transition—by safe Coulomb excitation. This is the first low-energy Coulomb excitation to be performed with a rare-isotope beam at the reaccelerated beam facility at the National Superconducting Cyclotron Laboratory. Finally, by demonstrating a negative spectroscopic quadrupole moment for the first-excited $${2}^{+}$$ state, it is found that any low-spin shape change in neutron-deficient selenium does not occur until $$^{70}\mathrm{Se}$$.

Authors:
 [1];  [1];  [2];  [3];  [2];  [2];  [2];  [2];  [4];  [2];  [4];  [2];  [4];  [4]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab. and Dept. of Physics and Astronomy
  3. Univ. of Massachusetts, Lowell, MA (United States). Dept. of Physics and Applied Physics
  4. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.
Publication Date:
Research Org.:
Michigan State Univ., East Lansing, MI (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20); National Science Foundation (NSF)
OSTI Identifier:
1466655
Alternate Identifier(s):
OSTI ID: 1465887; OSTI ID: 1469464
Report Number(s):
LLNL-JRNL-750400
Journal ID: ISSN 0031-9007
Grant/Contract Number:  
FG02-08ER41556; NA0003180; AC52-07NA27344; PHY-1565546
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 121; Journal Issue: 8; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; collective levels; spectroscopic factors & electromagnetic moments; radioactive beams; Physics - Nuclear physics and radiation physics

Citation Formats

Henderson, J., Wu, C. Y., Ash, J., Bender, P. C., Elman, B., Gade, A., Grinder, M., Iwasaki, H., Kwan, E., Longfellow, B., Mijatović, T., Rhodes, D., Spieker, M., and Weisshaar, D. Localizing the Shape Transition in Neutron-Deficient Selenium. United States: N. p., 2018. Web. doi:10.1103/PhysRevLett.121.082502.
Henderson, J., Wu, C. Y., Ash, J., Bender, P. C., Elman, B., Gade, A., Grinder, M., Iwasaki, H., Kwan, E., Longfellow, B., Mijatović, T., Rhodes, D., Spieker, M., & Weisshaar, D. Localizing the Shape Transition in Neutron-Deficient Selenium. United States. doi:10.1103/PhysRevLett.121.082502.
Henderson, J., Wu, C. Y., Ash, J., Bender, P. C., Elman, B., Gade, A., Grinder, M., Iwasaki, H., Kwan, E., Longfellow, B., Mijatović, T., Rhodes, D., Spieker, M., and Weisshaar, D. Wed . "Localizing the Shape Transition in Neutron-Deficient Selenium". United States. doi:10.1103/PhysRevLett.121.082502. https://www.osti.gov/servlets/purl/1466655.
@article{osti_1466655,
title = {Localizing the Shape Transition in Neutron-Deficient Selenium},
author = {Henderson, J. and Wu, C. Y. and Ash, J. and Bender, P. C. and Elman, B. and Gade, A. and Grinder, M. and Iwasaki, H. and Kwan, E. and Longfellow, B. and Mijatović, T. and Rhodes, D. and Spieker, M. and Weisshaar, D.},
abstractNote = {Neutron-deficient selenium isotopes are thought to undergo a rapid shape change from a prolate deformation near the line of beta stability towards oblate deformation around the line of $N=Z$. The point at which this shape change occurs is unknown, with inconsistent predictions from available theoretical models. A common feature in the models is the delicate nature of the point of transition, with the introduction of even a modest spin to the system sufficient to change the ordering of the prolate and oblate configurations. In this paper, we present a measurement of the quadrupole moment of the first-excited state in radioactive $^{72}\mathrm{Se}$—a potential point of transition—by safe Coulomb excitation. This is the first low-energy Coulomb excitation to be performed with a rare-isotope beam at the reaccelerated beam facility at the National Superconducting Cyclotron Laboratory. Finally, by demonstrating a negative spectroscopic quadrupole moment for the first-excited ${2}^{+}$ state, it is found that any low-spin shape change in neutron-deficient selenium does not occur until $^{70}\mathrm{Se}$.},
doi = {10.1103/PhysRevLett.121.082502},
journal = {Physical Review Letters},
number = 8,
volume = 121,
place = {United States},
year = {2018},
month = {8}
}

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