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Development of the isomer tagging system for mass measurements at OEDO-SHARAQ

ORAL

Abstract

The mass measurements of proton-rich unstable nuclei towards two-proton emitters have been performed utilizing the TOF-Bρ method with BigRIPS and OEDO-SHARAQ at RIBF. In this measurement, the secondary beam contained many nuclei with isomeric states in the pf-shell region. The isomer tagging provides us an exact fingerprint for the particle identification. While the measurement of isomeric ratio is critical for achieving the ground-state masses under a contaminant condition with isomeric states. Our purposes are discoveries of new isomers in this region and the determinations of their lifetimes and energies.

The isomer tagging system, which consists of two HPGe detectors, two CeBr3 detectors and an active stopper composed of two 10-mm-thick plastic scintillators, was installed downstream of the final focal plane of the OEDO-SHARAQ in the air. The secondary beam stopped inside of the active plastic stopper. The two HPGe detectors were installed in close proximity perpendicular to the beam direction, and CeBr3 detectors were tilted at 45 degrees. Additionally, a veto scintillator was placed downstream of the active stopper to identify events that beam particles penetrate the stopper. These energy and timing data of the HPGe, CeBr3, plastic stopper, and veto were recorded using digital signal processers parallelly with the mass measurement data through a timestamp scheme. In this presentation, we will introduce the isomer tagging system and discuss the performances.

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Presenters

  • Yuki Nakamura

    Tokyo City University

Authors

  • Yuki Nakamura

    Tokyo City University

  • Mei Amitani

    Tokyo City University

  • Chihaya Fukushima

    Tokyo City University

  • Daiki Nishimura

    Tokyo City University, Tokyo city University, Tokyo City Univ.

  • 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

  • Shutaro Hanai

    Center for Nuclear Study, the University of Tokyo, Center for Nuclear Study, The University of Tokyo

  • Eiji Ideguchi

    RCNP, Osaka University

  • Nobuaki Imai

    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, Center for Nuclear Study, University of Tokyo

  • Hiroki Nishibata

    Kyushu University

  • Kodai Okawa

    Center for Nuclear Study, the University of Tokyo

  • Takeshi Y Saito

    Center for Nuclear Study, the University of Tokyo, RIKEN AMO physics Laboratory, RIKEN AMO Physics Laboratory, Center for Nuclear Study, the University of Tokyo, Atomic, Molecular, and Optical Physics Laboratory, RIKEN

  • Daisuke Suzuki

    RIKEN Nishina Center

  • Hiroyuki Takahashi

    Tokyo City University

  • Hisato Tanaka

    Kyushu University

  • Keita Kawata

    Center for Nuclear Study, the University of Tokyo, Research Center for Nuclear Physics,Osaka University

  • Rin Yokoyama

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