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Schury, P.*; Ito, Yuta; Wada, Michiharu*
Nihon Butsuri Gakkai-Shi, 80(2), p.72 - 78, 2025/02
The multi-reflection time-of-flight mass spectrograph has recently become of great utility in the study of superheavy nuclei. The device efficiently uses each ion and its operation is amenable to the inclusion of a decay detector being coupled into the time-of-flight (TOF) ion impact detector. In this way, TOF-decay correlation can be measured to unambiguously differentiate low-yield radioactive ions from stable molecular ions or dark counts. This will eventually allow the technique to be applied to the study of extremely low-yield nuclei such as those of 
Nh and 
Mc isotopes.
Khuyagbaatar, J.*; Yakushev, A.*; D
llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.
Physical Review C, 102(6), p.064602_1 - 064602_9, 2020/12
Times Cited Count：100 Percentile：99.24(Physics, Nuclear)A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the 
Ti+
Bk and Ti+Cf fusion-evaporation reactions, respectively, at the gas-filled recoil separator TASCA. Over four months of irradiation, neither was detected at cross-section sensitivity levels of 65 and 200 fb, respectively. The non-observation of elements 119 and 120 is discussed within the concept of fusion-evaporation reactions including various theoretical predictions on the fission-barrier heights of superheavy nuclei in the region of the island of stability.
Aritomo, Yoshihiro*; Amano, Shota*; Okubayashi, Mizuki*; Yanagi, Baku*; Nishio, Katsuhisa; Ota, Masahisa*
Physics of Atomic Nuclei, 83(4), p.545 - 549, 2020/07
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)
-
spectroscopy using Si-Ge detector array installed at focal plane of GARISKaji, Daiya*; Morimoto, Koji*; Wakabayashi, Yasuo*; Takeyama, Mirei*; Asai, Masato
JPS Conference Proceedings (Internet), 6, p.030106_1 - 030106_4, 2015/06
A Si-Ge detector array was newly installed at the focal plane of the gas-filled recoil ion separator GARIS to perform - (X-rays) spectroscopy for superheavy nuclei. The performance of the array was tested using the 
Pb(
Ca,2n)
No and 
Pb(Ca,xn)
No [x=1,2,3] reactions. rays originating from the decay of No and 
No were clearly observed in prompt coincidence with the particles.
Kaji, Daiya*; Morimoto, Koji*; Wakabayashi, Yasuo*; Takeyama, Mirei*; Yamaki, Sayaka*; Tanaka, Kengo*; Haba, Hiromitsu*; Huang, M.*; Murakami, Masashi*; Kanaya, Jumpei*; et al.
JPS Conference Proceedings (Internet), 6, p.030107_1 - 030107_4, 2015/06
Performance of the new gas-filled recoil ion separator GARIS-II was investigated using asymmetric 
Ne-induced fusion reactions. The use of He-H
mixture gas for the gas-filled magnet significantly reduced background scattered particles detected at the focal-plane Si detector, and increased a transmission of the asymmetric reaction products. A target-identification system was newly installed for efficient measurements of excitation functions without changing beam energy nor target.
Koura, Hiroyuki
RIKEN Accelerator Progress Report, Vol.38, P. 9, 2005/05
We calculate proton-emission partial half lives and discuss dominant decay modes in the heavy and superheavy nuclidic region. The proton-emission partial half-lives are calculated from the one-dimensional WKB method with single-proton potentials and a mass formula that our group has developed. The calculated half lives well reproduce experimental ones in order of 100 or 1/100 which is similar predictability to other predictions as the alpha decay and the beta decay. We apply this result to calculation of branching ratios of nuclear decays considered the alpha decay, beta decay and spontaneous fission in the heavy and superheavy nuclide region. In this analysis we point out that proton-emitting nuclei are expected to be in the unknown proton-rich nuclidic region with 
. On the other hand, proton-rich nuclei with 
have much shorter spontaneous-fission half-lives than ones of proton emissions on this calculation, therefore we conclude that ground-state proton emissions would not occur in that region.
-decay spectroscopy of superheavy nucleiAsai, Masato
no journal, ,
To investigate nuclear structure of superheavy nuclei experimentally, spectroscopic methods which can reveal level structure of ground- and excited states are the most effective. In particular, fine-structure -decay spectroscopy is expected to be a very sensitive method because spectroscopic information can be obtained only through -particle measurements. However, it is difficult to measure particles of superheavy nuclei with high energy resolution. Moreover, the observed energy spectra are significantly distorted by coincidence summing effects. I would like to demonstrate how we can overcome these difficulties, and how useful the fine-structure -decay spectroscopy is to investigate nuclear structure of superheavy nuclei.
Miyashita, Naoto*; Asai, Masato; Fujii, Tomoki*; Kitagawa, Naoyuki*; Niwase, Toshitaka*; Sakaguchi, Satoshi*
no journal, ,
To elucidate nuclear shell structure of superheavy nuclei, we have developed a new internal conversion electron (ICE) spectroscopy technique using a silicon drift detector (SDD). Its performance was tested using ICE sources and it was found that the SDD has a superior energy resolution for low-energy electrons, which is very suitable and applicable to nuclear structure studies of superheavy nuclei.
