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In-beam γ-ray spectroscopy of 32Mg via direct reactions

Journal Article · · Physical Review. C
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [8];  [7];  [9];  [9];  [10];  [7];  [5];  [11];  [9];  [8];  [7];  [12] more »;  [13];  [9];  [8];  [8];  [9];  [7];  [14];  [9];  [8] « less
  1. Univ. of Tokyo, Wako (Japan); Univ. of Tennessee, Knoxville, TN (United States); OSTI
  2. Instituto de Estructura de la Materia, Madrid (Spain); Univ. of Tokyo (Japan); Central Michigan Univ., Mount Pleasant, MI (United States); Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.
  3. TRIUMF, Vancouver, BC (Canada)
  4. Univ. Autonoma de Madrid (Spain)
  5. Univ. of Tokyo, Wako (Japan)
  6. Univ. of Surrey, Guildford (United Kingdom)
  7. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Michigan State Univ., East Lansing, MI (United States)
  8. Central Michigan Univ., Mount Pleasant, MI (United States)
  9. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.
  10. Univ. of Guelph, ON (Canada)
  11. Technische Univ. Darmstadt (Germany)
  12. Institut Pluridisciplinaire Hubert Curien, Strasbourg (France)
  13. Central Michigan Univ., Mount Pleasant, MI (United States); Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.
  14. Univ. of Tokyo, Wako (Japan); Japan Atomic Energy Agency (JAEA), Tokai (Japan)
+ Show Author Affiliations
Background: The nucleus 32Mg (N=20 and Z=12) plays a central role in the so-called “island of inversion,” where in the ground states sd-shell neutrons are promoted to the fp-shell orbitals across the shell gap, resulting in the disappearance of the canonical neutron magic number N=20. Purpose: The primary goals of this work are to extend the level scheme of 32Mg, provide spin-parity assignments to excited states, and discuss the microscopic structure of each state through comparisons with theoretical calculations. Method: In-beam γ-ray spectroscopy of 32Mg was performed using two direct-reaction probes: one-neutron (two-proton) knockout reactions on 33Mg (34Si). Final-state exclusive cross sections and parallel momentum distributions were extracted from the experimental data and compared with eikonal-based reaction model calculations combined with shell-model overlap functions. Results: Owing to the remarkable selectivity of the one-neutron and two-proton knockout reactions, a significantly updated level scheme for 32Mg, which exhibits negative-parity intruder and positive-parity normal states, was constructed. The experimental results were confronted with four different nuclear structure models. Conclusions: In some of these models, different aspects of 32Mg and the transition into the island of inversion are well described. However, unexplained discrepancies remain, and, even with the help of these state-of-the-art theoretical approaches, the structure of this key nucleus is not yet fully captured.
Research Organization:
Michigan State Univ., East Lansing, MI (United States); Univ. of California, Oakland, CA (United States)
Sponsoring Organization:
Ministerio de Ciencia e Innovación (MICINN); Ministry of Education, Culture, Sports, Science, and Technology (MEXT) Japan; National Science Foundation (NSF); Science and Technology Facilities Council (STFC); USDOE Office of Science (SC)
Grant/Contract Number:
AC02-05CH11231; SC0020451
OSTI ID:
1979866
Journal Information:
Physical Review. C, Journal Name: Physical Review. C Journal Issue: 3 Vol. 105; ISSN 2469-9985
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Physics
ab initio calculations
direct reactions
energy levels & level densities
nuclear spin & parity
nuclear structure & decays
radioactive beams
shell model
spectroscopic factors & electromagnetic moments