II-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

β-γ Spectroscopy of 192 Re
H. Watanabe,∗1,∗2,∗3 Y. X. Watanabe,∗3 Y. Hirayama,∗3 A. N. Andreyev,∗4,∗5 T. Hashimoto,∗6 F. G. Kondev,∗7G. J. Lane,∗8 Yu. A. Litvinov,∗9 J. J. Liu,∗10 H. Miyatake,∗3 J. Y. Moon,∗6 A. I. Morales,∗11 M. Mukai,∗2,∗3,∗12
S. Nishimura,∗2 T. Niwase,∗2,∗13 M. Rosenbusch,∗3 P. Schury,∗3 M. Wada,∗3 and P. M. Walker∗14Decay spectroscopy of 192 Re has been carried out using the KEK Isotope Separation System (KISS).1–3) A
RI beam of 192 Re was produced via multi-nucleon transfer between a 50-particle-nA projectile of 136 Xe anda natural Pt target with a thickness of 10.7 mg/cm2 .
The 10.75-MeV/nucleon primary beam from the RIKEN
Ring Cyclotron was decelerated to 8.8 MeV/nucleon after passing through Ti degraders placed in front of thePt target. The reaction products were thermalized andneutralized in a doughnut-shaped gas cell ﬁlled with 80kPa gaseous argon, and then transported by a gas ﬂow
to the cell outlet, where a two-color, two-step resonant
laser ionization technique was applied for an unambiguous selection of a single element. The singly charged
192
Re+ ions were extracted through the RF ion guides
and reaccelerated at 20 keV, followed by mass separation
using the KISS spectrometer.
During 4.2 days of data run, about 1.5×105 192 Re nuclides were collected with an average intensity of 0.3 particles/s on a 12-µm-thick aluminized mylar tape at theend of the KISS beamline. The decay measurements
were carried out with three diﬀerent beam-on/oﬀ conditions of 90/180, 24/48, and 45/15 s in order to accommodate decays both from the ground state (T1/2 =16(1) s4) ) and from a previously reported long-lived iso5)
192
Re. The implantation posimer (T1/2 = 61+40−20 s ) intion was surrounded by a multi-segmented proportional
gas counter (MSPGC) that covered 80% of the 4π solid
angle with two layers of 16 counters.6) The MSPGC wassurrounded by four large-volume Clover-type HPGe detectors in a close geometry, having a γ-ray add-backed
full-energy peak eﬃciency of 7.8% at 1 MeV.
Figure 1 shows an example of the β-delayed γ-ray coincidence spectrum and the decay scheme of 192 Re obtained in the present work. More details about the experimental results and physics discussion are describedin Ref. 7).
∗1

School of Physics, Beihang University
RIKEN Nishina Center∗3 Wako Nuclear Science Center (WNSC), IPNS, KEK∗4 Department of Physics, University of York
∗5 Advanced Science Research Center, Japan Atomic Energy
Agency (JAEA)∗6 Rare Isotope Science Project, Institute for Basic Science (IBS)∗7 Physics Division, Argonne National Laboratory∗8 Department of Nuclear Physics, Australian National University∗9 GSI Helmholtzzentrum für Schwerionenforschung∗10 Department of Physics, the University of Hong Kong
∗11 Instituto de Fisica Corpuscular (CSIC-Universitat de Valencia)∗12 Graduate School of Sciences and Technology, University ofTsukuba∗13 Department of Physics, Kyushu University∗14 Department of Physics, University of Surrey∗2Fig. 1. Top: γ-ray energy spectrum measured in coincidencewith MSPGC following implantation of 192 Re. Transitions in 192 Os are labeled with their energy values, whileγ-ray peaks that originate from the room background andbeam contaminants are marked with crosses and asterisk,respectively. The inset magnifies a high-energy region.
Bottom: Level scheme of 192 Os populated in the β decay of 192 Re. The observed γ rays are consistent withthose reported in Ref. 4). The superscript “1u” indicatesfirst-forbidden unique β decay.

References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
353, 4 (2015).
2) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
376, 52 (2016).
3) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
412, 11 (2017).
4) C. M. Baglin, Nucl. Data Sheets 113, 1871 (2012).
5) M. W. Reed et al., Phys. Rev. C 86, 054321 (2012).
6) M. Mukai et al., Nucl. Instrum. Methods Phys. Res. A
884, 1 (2018).
7) H. Watanabe et al., Phys. Lett. B 814, 136088 (2021).

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