Structure of 30Mg Studied by beta-decay spectroscopy of spin-polarized 30Na -- shape coexistence in 30Mg --

2013 Fiscal Year Final Research Report

• Project/Area Number: 22340058
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Osaka University
• Principal Investigator: SHIMODA Tadashi 大阪大学, 理学(系)研究科(研究院), 教授 (70135656)
• Co-Investigator(Kenkyū-buntansha): ODAHARA Atsuko 大阪大学, 大学院理学研究科, 准教授 (30264013)
• Co-Investigator(Renkei-kenkyūsha): MIYATAKE Hiroari 高エネルギー加速器研究機構, 素粒子原子核研究所, 教授 (50190799)
• Project Period (FY): 2010-04-01 – 2013-03-31
• Keywords: 中性子過剰核 / island of inversion / 30Mgの核構造 / スピン・パリティ / ガンマ線 / ベータ崩壊の非対称性 / スピン編極 / レーザー光ポンピング

Research Abstract

We have been studying the structure of Mg isotopes in the region of the N=20 island of inversion, to clarify the structure change as a function of the neutron number. The experiments were performed by our unique method of b-decay spectroscopy taking advantage of highly-spin-polarized radioactive nuclear beams at TRIUMF. The b-decay asymmetry in the Na-isotope decay enables unambiguous spin-parity assignments of the levels in the daughter Mg isotope, and it becomes possible to compare the experimental data and theoretical predictions on a level-by-level basis.
The present work focused on the results of the b-decay of 30Na-->30Mg. From the detailed analyses, fourteen g-transitions were newly found and four new levels at 4.683, 4.694, 5.897 and 6.064~MeV were also found in 30Mg. It should be emphasized that the spins and parities of ten levels have been assigned for the first time. Five of them were firmly assigned. An evidence of shape coexistence was proposed.

Research Products

• [Journal Article] Nuclear structure explored byβ-delayed decay spectroscopy of spin-polarized radioactive nuclei at TRIUMF ISAC-1 - Intruder configurations in ^<29>Mg and ^<30>Mg, the nuclei in the region of island of inversion - (2014)
  • Author(s): T. Shimoda, K. Tajiri, K. Kura, A. Odahara, M. Suga, Y. Hirayama, N. Imai, H.Miyatake, M. Pearson, C. D. P. Levy, K. P. Jackson, R. Legillon, C. Petrache, T. Fukuchi, N. Hamatani, T. Hori, M. Kazato, Y. Kenmoku, T. Masue, H. Nishibata, T. Suzuki, A. Takashima, R. Yokoyama
  • Journal Title: Hyperfine Interactions Volume: Vol. 225 Pages: 183-191
  • DOI: 10.1007/s10751-013-0895-5
  • Peer Reviewed
• [Journal Article] Structure of ^28Mg studied byβ-decay spectro- scopy of spin-polarized 28Na : The first step of systematic studies on neutron-rich Mg isotopes (2012)
  • Author(s): K. Kura, K. Tajiri, T.Shimoda, A.Odahara, T. Hori, M. Kazato, T. Masue, M. Suga, A. Takashima, T. Suzuki, T. Fukuchi, Y. Hirayama, N. Imai, H.Miyatake, M. Pearson, C. D. P. Levy, and K. P. Jackson
  • Journal Title: Physical Review C Volume: Vol. 85 Pages: 034310-1-9
  • DOI: 10.1103/PhysRevC.85.034310
  • Peer Reviewed
• [Journal Article] Romain Leguillon and Costel Petrache, Structure of Mg Isotope Studied byβ-Decay Spectroscopy of Spin-Polarized Na Isotopes - Shape Coexistence in 30Mg - (2012)
  • Author(s): Tadashi Shimoda, Kunihiko Tajiri, Atsuko Odahara, Masaki Suga, Noriaki Hamatani, Hiroki Nishibata, Jun Takatsu, Rin Yokoyama, Yoshikazu Hirayama, Nobuaki Imai, Hiroari Miyatake, Mathew Pearson, C. D. P. Levy, K. P. Jackson
  • Journal Title: Progress of Theoretical Physics Supplement Volume: Vol. 196 Pages: 310-315
  • DOI: 10.1143/PTPS.196.310
  • Peer Reviewed
• [Presentation] Structure of Mg Isotope Studied by beta-Decay Spectroscopy of Spin-Polarized Na Isotopes - Shape Coexistence in ^30Mg- (2012)
  • Author(s): A. Odahara
  • Organizer: Nuclear Structure 2012 (NS12)
  • Place of Presentation: Argonne, USA
  • Year and Date: 20120813-17
• [Presentation] Structure of Mg isotope studied through beta-delayed decay of spin-polarized Na isotopes (2011)
  • Author(s): T. Shimoda
  • Organizer: Frontier Issues in Physics of Exotic Nuclei (YKIS2011)
  • Place of Presentation: Kyoto
  • Year and Date: 20111011-15
• [Presentation] スピン偏極した30Naのβ遅発崩壊分光による中性子過剰な30Mgの構造の研究II (2011)
  • Author(s): 田尻邦彦
  • Organizer: 日本物理学会、秋の学会
  • Place of Presentation: 弘前大学
  • Year and Date: 20110916-19
• [Presentation] Study of Neutron-Rich Mg Isotopes through beta-Decay of Spin-Polarized Na Isotopes (2011)
  • Author(s): K. Tajiri
  • Organizer: RIBF ULIC and CNS Symposium on Frontier of Gamma-ray Spectroscopy (Gamma11)
  • Place of Presentation: Saitama
  • Year and Date: 20110630-0702
• [Presentation] Exploring Mg Isotope Structures through Beta-Delayed Decay of Spin-Polarized Na Isotopes (2011)
  • Author(s): T.Shimoda
  • Organizer: French Japanese Symp. on Nuclear Structure Problems
  • Place of Presentation: Saitama, Japan
  • Year and Date: 20110104-08
• [Presentation] Exploring neutron-rich nuclear structures through beta-delayed decay of spin-polarized isotopes (2010)
  • Author(s): T. Shimoda
  • Organizer: Halo 2010 Symp
  • Place of Presentation: Kanagawa, Japan
  • Year and Date: 20101206-09
• [Presentation] Beta-decay spectroscopy with spin-polarized radioactive nuclei (2010)
  • Author(s): T. Shimoda
  • Organizer: DESIR (Decay, Excitation and Storage of Radioactive Ions) workshop
  • Place of Presentation: Hogenheuvel College, Leuven, Belgium
  • Year and Date: 20100527-28
• [Presentation] Structure of Neutron-Rich ^<28,29>Mg Studied throughβ-Decay of Spin Polarized ^<28,29>Na Beams at TRIUMF (2010)
  • Author(s): K. Tajiri
  • Organizer: Int. Symp. on Forefronts of Researches in Exotic Nuclear Structures–Niigata2010
  • Place of Presentation: Niigata, Japan
  • Year and Date: 20100301-04
• [Presentation] Structure of Mg isotopes explored by beta-decay of spin-polarize Na isotopes (2010)
  • Author(s): T. Shimoda
  • Organizer: EFES-NSCL workshop on Perspectives on the modern shell model and related experimental topics
  • Place of Presentation: Michigan, USA
  • Year and Date: 20100204-06
• [Remarks]
  • URL: http://adam.phys.sci.osaka-u.ac.jp/