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Reaching the prolate-oblate boundary at 𝑁=116 via first fragmentation of a 198Pt beam: Sharp transition to triaxiality in 189Ta

Journal Article · · Physical Review. C
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  1. University of Massachusetts, Lowell, MA (United States); TRIUMF, Vancouver, BC (Canada)
  2. University of Massachusetts, Lowell, MA (United States)
  3. Michigan State University, East Lansing, MI (United States)
  4. University of Massachusetts, Lowell, MA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
  5. Central Michigan University, Mount Pleasant, MI (United States)
  6. Western Michigan University, Kalamazoo, MI (United States)
  7. University of Massachusetts, Lowell, MA (United States); University of Cambridge (United Kingdom)
  8. RIKEN Nishina Center, Saitama (Japan)
  9. Michigan State University, East Lansing, MI (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
  10. Michigan State University, East Lansing, MI (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
  11. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
  12. Michigan State University, East Lansing, MI (United States); Ohio University, Athens, OH (United States)
  13. Michigan State University, East Lansing, MI (United States); Florida State University, Tallahassee, FL (United States)
  14. Central Michigan University, Mount Pleasant, MI (United States); Chinese Academy of Sciences, Gansu (China)
  15. University of Massachusetts, Lowell, MA (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)
  16. Brookhaven National Laboratory (BNL), Upton, NY (United States)
+ Show Author Affiliations
High-spin isomers in very-neutron-rich 𝐴≈190 Hf-Ta-W nuclei were populated via the pioneering fragmentation of a 198Pt primary beam at the National Superconducting Cyclotron Laboratory. The nuclei were implanted in a Si detector stack surrounded by the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) to detect delayed 𝛾 rays, providing first level schemes using 𝛾−𝛾 coincidence data from isomeric decays in this previously inaccessible region of the nuclear chart. Here, a sudden transition to a strong triaxial shape is observed in the very-neutron-rich 189Ta (𝑁 = 116) nucleus from axially prolate shapes in lighter Ta isotopes, providing a critical experimental benchmark for competing theoretical predictions of nuclear-shape evolution.
Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Michigan State University, East Lansing, MI (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE Office of Science (SC), Nuclear Physics (NP)
Grant/Contract Number:
AC02-05CH11231; AC02-98CH10886; FG02-94ER40848; SC0012704; SC0019034; SC0022538; SC0023633
OSTI ID:
3001577
Alternate ID(s):
OSTI ID: 2531123
OSTI ID: 2587085
OSTI ID: 2529408
Report Number(s):
BNL--228586-2025-JAAM
Journal Information:
Physical Review. C, Journal Name: Physical Review. C Journal Issue: 3 Vol. 111; ISSN 2469-9985; ISSN 2469-9993
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

150 ≤ A ≤ 189
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Collective levels
Collective models
Energy levels
High spin states
Isomer decays
Lifetimes & widths
Nuclear fragmentation
Nuclear shapes and moments