Investigating Shell Structure: Mass Measurements of Sc, Ti, and V Isotopes at new magic N = 32 and N = 34

ORAL

Abstract

In this study, we present our findings on the precise mass measurements of 55Sc, 55-58Ti, and 55-59V isotopes. These measurements were obtained during the initial commissioning campaign of the ZD-MRTOF system at the RIBF/RIKEN. Our focus is to examine the implications of these masses on the shell structure at N=32 and N=34, specifically in relation to the deformation towards N=40. The experimental setup, newly installed downstream of the ZeroDegree (ZD) spectrometer at the BigRIPS facility (RIBF/RIKEN), consists of a radiofrequency (RF) carpet-type helium gas cell combined with a multi-reflection time-of-flight (MRTOF) mass spectrograph. In the first low-energy experiment conducted at BigRIPS, high-energy products were decelerated and captured in helium gas. Subsequently, they were extracted through an aperture via RF microstructure into a Paul trap ion guide structure. The cooled and thermalized ions were then injected into the MRTOF system, forming a high-quality beam for conducting high-precision mass measurements. We provide a detailed account of the new cryogenic gas cell and the mass analysis methods employed in this experiment. Additionally, we outline our future plans for mass measurements, particularly focusing on the N=126 region. This region is of significant interest as it is proximate to waiting point nuclei relevant to the third peak of the r-process.

*This work was supported by the Japan Society for the Promotion of Science KAKENHI (Grants No. 2200823, No. 24224008, No. 24740142, No. 15H02096, No. 15K05116, No. 17H01081, No. 17H06090, No. 18K13573, No. 18H05462, No. 19H00679, No. 19K14750, No. 20H05648, No. 21K13951, No. 22H01257, and No. 22H04946), RIKEN Junior Research Associate Program, the RIKEN programme for Evolution of Matter in the Universe (r-EMU), the UK STFC award ST/P003885/1, and the Royal Society. The MCSM and conventional shell-model calculations were performed on the supercomputer Fugaku at RIKEN AICS (hp210165, hp220174). This work was supported in part by MEXT as "Program for Promoting Researches on the Supercomputer Fugaku" (Simulation for basic science: from fundamental laws of particles to creation of nuclei) and by JICFuS.

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Publication: [1] "Study of the N = 32 and N = 34 Shell Gap for Ti and V by the First High-Precision Multireflection Time-of-Flight Mass Measurements at BigRIPS-SLOWRI" S. Iimura, M. Rosenbusch, A. Takamine et al., Physical Review Letters 130, 012501 (2023).
[2] "The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN's RIBF facility" M. Rosenbusch et al., Nuclear Instruments and Methods in Physics Research Section A 1047 167824 (2022).

Presenters

  • Shun Iimura

    • Department of Physics, College of Science, Rikkyo University
    • Rikkyo University
    • RNC, RIKEN
    • Department of Physics, Rikkyo University

Authors

  • Shun Iimura

    • Department of Physics, College of Science, Rikkyo University
    • Rikkyo University
    • RNC, RIKEN
    • Department of Physics, Rikkyo University

  • Marco Rosenbusch

    • RIKEN Nishina Center
    • RIKEN Nishina Center for Accelerator-Based Science
    • RIKEN Nishina Center for Accelerator-Based Science, Japan
    • WNSC, KEK

  • Aiko Takamine

    • RIKEN Nishina Center
    • RIKEN Nishina center
    • RNC, RIKEN
    • RIKEN Nishina Center for Accelerator-Based Science, Japan

  • Yusuke Tsunoda

    • Center for Nuclear Study, the University of Tokyo
    • University of Tsukuba

  • Michiharu Wada

    • KEK Wako Nuclear Science Center
    • High Energy Accelerator Research Organization (KEK)
    • KEK
    • WNSC, IPNS, High Energy Accelerator Research Organization (KEK)
    • Wako Nuclear Science Center (WNSC), KEK, Japan
    • WNSC, KEK
    • Wako Nuclear Science Center (WNSC), KEK

  • Sidong Chen

    • The University of Hong Kong
    • University of York, UK

  • Dongsheng Hou

    • Chinese Academy of Sciences
    • Institute of Modern Physics (IMP), China

  • Wenduo Xian

    • Hong Kong University
    • The University of Hong Kong
    • The University of Hong Kong, China
    • Department of Physics, The University of Hong Kong

  • Hironobu Ishiyama

    • RIKEN Nishina Center
    • RIKEN Nishina Center for Accelerator-Based Science
    • RIKEN Nishina Center for Accelerator-Based Science, Japan
    • RNC, RIEKN

  • Shuxiong Yan

    • Jinan University

  • Peter Schury

    • High Energy Accelerator Research Organization (KEK)
    • WNSC, IPNS, High Energy Accelerator Research Organization (KEK)
    • Wako Nuclear Science Center (WNSC), KEK, Japan
    • WNSC, KEK
    • Wako Nuclear Science Center (WNSC), KEK
    • KEK Wako Nuclear Science Center

  • Heather L Crawford

    • Lawrence Berkeley National Laboratory

  • Pieter Doornenbal

    • RIKEN Nishina Center

  • Yoshikazu Hirayama

    • KEK Wako Nuclear Science Center
    • KEK
    • High Energy Accelerator Research Organization (KEK)
    • WNSC, IPNS, High Energy Accelerator Research Organization (KEK)
    • WNSC, KEK
    • Wako Nuclear Science Center (WNSC), KEK

  • Yuta Ito

    • Japan Atomic Energy Agency
    • JAEA, ASRC
    • JAEA, ASRC, Japan
    • Japan Atomic Energy Agency (JAEA)

  • Sota Kimura

    • RIKEN Nishina Center
    • Wako Nuclear Science Center (WNSC), KEK

  • Takuma Koiwai

    • The University of Tokyo
    • Univ. of Tokyo

  • Takao M Kojima

    • RIKEN

  • Hiroyuki Koura

    • Japan Atomic Energy Agency

  • Jenny H. C. Lee

    • The University of Hong Kong

  • Jiajian Liu

    • The University of Hong Kong

  • Shin'ichiro Michimasa

    • CNS, The University of Tokyo
    • The University of Tokyo
    • Center for Nuclear Study, the University of Tokyo
    • Center for Nuclear Study, The University of Tokyo
    • CNS, University of Tokyo
    • CNS, University of Tokyo, Japan

  • Hiroari Miyatake

    • High Energy Accelerator Research Organization (KEK)
    • WNSC, IPNS, High Energy Accelerator Research Organization (KEK)
    • KEK
    • WNSC, KEK

  • Jun-young Moon

    • Institute for Basic Science

  • Shunji Nishimura

    • RIKEN Nishina Center

  • Sarah Naimi

    • RIKEN Nishina Center

  • Toshitaka Niwase

    • KEK Wako Nuclear Science Center
    • High Energy Accelerator Research Organization (KEK)
    • WNSC, IPNS, High Energy Accelerator Research Organization (KEK)
    • KEK
    • Wako Nuclear Science Center (WNSC), KEK, Japan
    • Wako Nuclear Science Center (WNSC), KEK

  • Atsuko Odahara

    • Osaka University

  • Takaharu Otsuka

    • Univ of Tokyo

  • Stefanos Paschalis

    • University of York

  • Marina Petri

    • University of York

  • Noritaka Shimizu

    • Center for Computational Sciences, University of Tsukuba
    • University of Tsukuba

  • Tetsu Sonoda

    • RIKEN Nishina Center

  • Daisuke Suzuki

    • RIKEN Nishina Center

  • Yutaka X Watanabe

    • KEK Wako Nuclear Science Center
    • KEK
    • High Energy Accelerator Research Organization (KEK)
    • WNSC, IPNS, High Energy Accelerator Research Organization (KEK)
    • Wako Nuclear Science Center (WNSC), KEK, Japan
    • WNSC, KEK
    • Wako Nuclear Science Center (WNSC), KEK

  • Kathrin Wimmer

    • The University of Tokyo
    • GSI, Germany

  • Hermann Wollnik

    • New Mexico State University