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Journal Articles

New result in the production and decay of an isotope, $$^{278}$$113 of the 113th element

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sumita, Takayuki*; Wakabayashi, Yasuo*; Yoneda, Akira*; Tanaka, Kengo*; et al.

Journal of the Physical Society of Japan, 81(10), p.103201_1 - 103201_4, 2012/10

https://doi.org/10.1143/JPSJ.81.103201
 Times Cited Count：167 Percentile：97.27(Physics, Multidisciplinary)

An isotope of the 113th element, $$^{278}$$113, was produced in a nuclear reaction with a $$^{70}$$Zn beam on a $$^{209}$$Bi target. We observed six consecutive $$alpha$$ decays following the implantation of a heavy particle in nearly the same position in the semiconductor detector, in extremely low background condition. The fifth and sixth decays are fully consistent with the sequential decays of $$^{262}$$Db and $$^{258}$$Lr both in decay energies and decay times. This indicates that the present decay chain consisted of $$^{278}$$113, $$^{274}$$Rg (Z = 111), $$^{270}$$Mt (Z = 109), $$^{266}$$Bh (Z = 107), $$^{262}$$Db (Z = 105), and $$^{258}$$Lr (Z = 103) with firm connections. This result, together with previously reported results from 2004 and 2007, conclusively leads the unambiguous production and identification of the isotope $$^{278}$$113, of the 113th element.

Journal Articles

Attempt to produce the 3rd chain of $$^{278}$$113

Morimoto, Koji*; Morita, Kosuke*; Kaji, Daiya*; Akiyama, Takahiro*; Goto, Shinichi*; Haba, Hiromitsu*; Ideguchi, Eiji*; Katori, Kenji*; Koura, Hiroyuki; Kudo, Hisaaki*; et al.

RIKEN Accelerator Progress Report, Vol.42, P. 15, 2009/00

http://www.rarf.riken.jp/researcher/APR/Document/2008.pdf

In 2003-2007, we had performed an experiment to synthesize an element 113 by a $$^{209}$$Bi$$+$$ $$^{70}$$Zn reaction using a gas-filled recoil ion separator (GARIS) at RIKEN Nishina-Center. In a total of 241 days of net irradiation time experiment, two decay chains were observed and assigned from an isotope $$^{278}$$113. The cross section of the $$^{209}$$Bi($$^{70}$$Zn,n)$$^{278}$$113 reaction was determined to be 31$$^{+40}_{-20}$$ fb at that time. In order to increase the statistics of the decay property, we continued to produce more decay chains. The experiment was carried out from January 7 to March 31, 2008. The experimental conditions were identical to those used in the previous experiment. $$^{70}$$Zn ion beam of 353 MeV was extracted from RILAC. The net irradiation time was 83 days and the total dose of $$^{70}$$Zn was 2.28$$times10^{19}$$. In the present expriment any candidate of $$^{278}$$113 was not observed. Then combining the results of the present and previous experiments, the production cross section of $$^{278}$$113 was determined to be 22$$^{+29}_{-19}$$ fb.

Journal Articles

Startup of superheavy element chemistry at RIKEN

Haba, Hiromitsu*; Akiyama, Takahiro*; Kaji, Daiya*; Kikunaga, Hidetoshi*; Kuribayashi, Takahiro*; Morimoto, Koji*; Morita, Kosuke*; Oe, Kazuhiro*; Sato, Nozomi*; Shinohara, Atsushi*; et al.

European Physical Journal D, 45(1), p.81 - 86, 2007/10

https://doi.org/10.1140/epjd/e2007-00135-4
 Times Cited Count：11 Percentile：49.57(Optics)

A review is given on the startup of the superheavy element (SHE) chemistry at RIKEN. A gas-jet transport system for the SHE chemistry has been coupled to the gas-filled recoil ion separator GARIS at the RIKEN Linear Accelerator. The performance of the system was appraised using $$^{206}$$Fr and $$^{245}$$Fm produced in the $$^{169}$$Tm($$^{40}$$Ar,3${it n}$)$$^{206}$$Fr and $$^{208}$$Pb($$^{40}$$Ar,3${it n}$)$$^{245}$$Fm reactions, respectively. The $$alpha$$ particles of $$^{206}$$Fr and $$^{245}$$Fm separated with GARIS and transported by the gas-jet were identified with a rotating wheel system for $$alpha$$ spectrometry under desired low background condition. The high gas-jet efficiencies over 80% were independent of the beam intensities up to 2 particle $$mu$$A. A gas-jet coupled target system for the production of SHEs was also installed on the beam line of the RIKEN K70 AVF cyclotron. The gas-jet transport of $$^{255}$$No and $$^{261}$$Rf produced in the $$^{238}$$U($$^{22}$$Ne,5${it n}$)$$^{255}$$No and $$^{248}$$Cm($$^{18}$$O,5${it n}$)$$^{261}$$Rf reactions, respectively, was conducted for the future chemical studies of $$^{265}$$Sg via the $$^{248}$$Cm($$^{22}$$Ne, 5${it n}$)$$^{265}$$Sg reaction.

Journal Articles

Experiment on synthesis of an isotope $$^{277}$$112 by $$^{208}$$Pb + $$^{70}$$Zn reaction

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Akiyama, Takahiro*; Goto, Shinichi*; Haba, Hiromitsu*; Ideguchi, Eiji*; Katori, Kenji*; Koura, Hiroyuki; Kudo, Hisaaki*; et al.

Journal of the Physical Society of Japan, 76(4), p.043201_1 - 043201_5, 2007/04

https://doi.org/10.1143/JPSJ.76.043201
 Times Cited Count：150 Percentile：95.98(Physics, Multidisciplinary)

The production and decay of $$^{277}$$112 has been investigated using a gas-filled recoil ion separator in irradiations of $$^{208}$$Pb targets with $$^{70}$$Zn beam at 349.5 MeV. We have observed two $$alpha$$-decay chains that can be assigned to subsequent decays from $$^{277}$$112 produced in the 208 Pb($$^{70}$$Zn,n) reaction. After emitting four consecutive $$alpha$$-particles, the both chains ended by spontaneous fission decays of $$^{261}$$Rf and decay energies and decay times of the both chains obtained in the present work agree well with those reported by a group at Gesellschaft f$"u$r Schwerionenforschung (GSI), Germany. The present result gives the first clear confirmation of the discovery of $$^{277}$$112 and its $$alpha$$-decay products $$^{273}$$Ds reported previously.

Journal Articles

Observation of second decay chain from $$^{278}$$113

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Akiyama, Takahiro*; Goto, Shinichi*; Haba, Hiromitsu*; Ideguchi, Eiji*; Katori, Kenji*; Koura, Hiroyuki; Kikunaga, Hidetoshi*; et al.

Journal of the Physical Society of Japan, 76(4), p.045001_1 - 045001_2, 2007/04

https://doi.org/10.1143/JPSJ.76.045001
 Times Cited Count：199 Percentile：97.44(Physics, Multidisciplinary)

The production and decay of $$^{278}$$113 has been investigated using a gas-filled recoil ion separator in irradiations of $$^{209}$$Bi targets with $$^{70}$$Zn beam at 353 MeV. We have observed one $$alpha$$-decay chain that can be assigned to subsequent decays from $$^{278}$$113 produced in the $$^{209}$$Bi($$^{70}$$Zn,n) reaction. After emitting four consecutive $$alpha$$-particles, the both chains ended by spontaneous fission decays of $$^{262}$$Db and decay energies and decay times of the both chains obtained in the present work agree well with those reported by our group in 2004. The present result gives the first clear confirmation of the discovery of $$^{278}$$113 and its $$alpha$$-decay products $$^{274}$$Rg reported previously.

Journal Articles

Experiments on synthesis of the heaviest element at RIKEN

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Akiyama, Takahiro*; Goto, Shinichi*; Haba, Hiromitsu*; Ideguchi, Eiji*; Kanungo, R.*; Katori, Kenji*; Kikunaga, Hidetoshi*; et al.

AIP Conference Proceedings 891, p.3 - 9, 2007/03

https://doi.org/10.1063/1.2713494

A series of experiments studying the productions and their decays of the heaviest elements have been performed by using a gas-filled recoil separator GARIS at RIKEN. Results on the isotope of the 112th element, $$^{277}$$112, and on that of the 113th element, $$^{278}$$113, are reviewed. Two decay chains which are assigned to be ones originating from the isotope $$^{277}$$112 were observed in the $$^{208}$$Pb($$^{70}$$Zn, n) reaction. The results provide a confirmation of the production and decay of the isotope $$^{277}$$112 reported by a research group at GSI, Germany, produced via the same reaction by using a velocity filter. Two decay chains, both consisted of four consecutive alpha decays followed by a spontaneous fission, were observed also in the reaction $$^{209}$$Bi($$^{70}$$Zn, n). Those are assigned to be the convincing candidate events of the isotope of the 113th element, $$^{278}$$113, and its daughter nuclei. $$^{274}$$Rg, $$^{270}$$Mt, $$^{266}$$Bh, and $$^{262}$$Db.

Journal Articles

Experiment on the synthesis of element 113 in the reaction $$^{209}$$Bi($$^{70}$$Zn,n)$$^{278}$$113

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Akiyama, Takahiro*; Goto, Shinichi*; Haba, Hiromitsu*; Ideguchi, Eiji*; Kanungo, R.*; Katori, Kenji*; Koura, Hiroyuki; et al.

Journal of the Physical Society of Japan, 73(10), p.2593 - 2596, 2004/10

https://doi.org/10.1143/JPSJ.73.2593
 Times Cited Count：487 Percentile：99.22(Physics, Multidisciplinary)

The isotope of the 113th element, $$^{278}$$113, and its daughter nuclei, $$^{274}$$111 and $$^{270}$$Mt, were obserbed, for the first time, in the $$^{209}$$Bi + $$^{70}$$Zn reaction at a beam energy of 349.1 MeV with a total dose of 1.6$$times$$10$$^{19}$$. The production cross section of $$^{278}$$113 is deduced to be $$57^{+154}_{-47}$$ fb ($$10^{-39}$$ cm$$^2$$).

Oral presentation

TOPO reversed-phase extraction behavior of rutherfordium in HCl solutions

Toyoshima, Atsushi; Kasamatsu, Yoshitaka; Tsukada, Kazuaki; Haba, Hiromitsu*; Asai, Masato; Ishii, Yasuo; Tome, Hayato; Sato, Tetsuya; Nishinaka, Ichiro; Nagame, Yuichiro; et al.

no journal, , 

no abstracts in English

Oral presentation

Anion-exchange behavior of element 105, Db, in HF/HNO$$_{3}$$ media

Kasamatsu, Yoshitaka; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Ishii, Yasuo; Tome, Hayato; Nishinaka, Ichiro; Akiyama, Kazuhiko*; Kikunaga, Hidetoshi*; et al.

no journal, , 

Dubnium-262 was produced in the $$^{248}$$Cm($$^{19}$$F, 5${it n}$) reaction at the JAEA tandem accelerator. Adsorption of Db on the anion-exchange resin was investigated in 0.89 M HF/0.3 M HNO$$_{3}$$ solution. The anion-exchange behavior of Nb, Ta, and Pa as homologues of Db was also examined in details in HF/HNO$$_{3}$$ solutions. From the comparison of those results, we found that the adsorption of Db on the anion-exchange resin is considerably weaker than that of Ta and is relatively similar to those of Nb and Pa in the studied conditions.

Oral presentation

Chemical behavior of element-105, Db, in mixed HF/HNO$$_{3}$$ solutions

Kasamatsu, Yoshitaka; Tome, Hayato; Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Nishinaka, Ichiro; Sato, Tetsuya; Shinohara, Nobuo; Nagame, Yuichiro; et al.

no journal, , 

Anion-exchange behavior of $$^{262}$$Db (half-life ${it T$_{1/2}$}$ = 34 s) produced in the $$^{248}$$Cm($$^{19}$$F, 5${it n}$) reaction at the JAEA tandem accelerator was investigated in the mixed 0.89 M HF/0.3 M HNO$$_{3}$$ solution ([F$$^{-}$$] = 3 $$times$$ 10$$^{-3}$$ M) with the automated ion-exchange separation apparatus coupled with the detection system for alpha-spectroscopy (AIDA). Anion-exchange behavior of its lighter homologues, Nb and Ta, was also studied under the same conditions using $$^{88}$$Nb (${it T$_{1/2}$}$ = 14.3 min) and $$^{170}$$Ta (${it T$_{1/2}$}$ = 6.76 min) produced in the $$^{nat}$$Ge($$^{19}$$F, ${it xn}$) and $$^{nat}$$Gd($$^{19}$$F, ${it xn}$) reactions, respectively. It was found that the adsorption probability on the anion-exchange resin is in the order of Ta $$>$$ Nb $$sim$$ Db under the present condition.

Oral presentation

Adsorption of element-105 (Db) on anion-exchange resin in HF/HNO$$_{3}$$ solutions

Kasamatsu, Yoshitaka; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Ishii, Yasuo; Tome, Hayato; Nishinaka, Ichiro; Akiyama, Kazuhiko*; Kikunaga, Hidetoshi*; et al.

no journal, , 

Dubnium-262 was produced in the nuclear reaction of $$^{248}$$Cm($$^{19}$$F,5n)$$^{262}$$Db using the JAEA Tandem accelerator. The reaction products were rapidly transported to the chemistry laboratory and the anion-exchange behavior of Db in HF/HNO$$_{3}$$ media was investigated with an on-line rapid ion-exchange apparatus. Based on the comparison of the behavior of Db with that of its homologues (Nb, Ta, and Pa), the fluoride complex formation of Db was discussed.

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