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Journal Articles

Summary results of subsidy program for the "Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy and Thermal Behavior Estimation of Fuel Debris))"

Koyama, Shinichi; Nakagiri, Toshio; Osaka, Masahiko; Yoshida, Hiroyuki; Kurata, Masaki; Ikeuchi, Hirotomo; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Takano, Masahide; et al.

Hairo, Osensui Taisaku jigyo jimukyoku Homu Peji (Internet), 144 Pages, 2021/08

JAEA performed the subsidy program for the "Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy and Thermal Behavior Estimation of Fuel Debris))" in 2020JFY. This presentation summarized briefly the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning and Contaminated Water Management.

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

 Times Cited Count:142 Percentile:97.35(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

Sulfate complexation of element 104, Rf, in H$$_{2}$$SO$$_{4}$$/HNO$$_{3}$$ mixed solution

Li, Z.*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Nagame, Yuichiro; Sch$"a$del, M.; Pershina, V.*; et al.

Radiochimica Acta, 100(3), p.157 - 164, 2012/03

 Times Cited Count:10 Percentile:65.97(Chemistry, Inorganic & Nuclear)

Journal Articles

Anionic fluoro complex of element 105, Db

Kasamatsu, Yoshitaka*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Li, Z.; Ishii, Yasuo; Tome, Hayato*; Sato, Tetsuya; Kikuchi, Takahiro; Nishinaka, Ichiro; et al.

Chemistry Letters, 38(11), p.1084 - 1085, 2009/10

 Times Cited Count:14 Percentile:49.52(Chemistry, Multidisciplinary)

We report on the characteristic anion-exchange behavior of the superheavy element dubnium (Db) with atomic number Z = 105 in HF/HNO$$_{3}$$ solution at the fluoride ion concentration [F$$^{-}$$] = 0.003 M. The result clearly demonstrates that the fluoro complex formation of Db is significantly different from that of the group-5 homologue Ta in the 6th period of the periodic table while the behavior of Db is similar to that of the lighter homologue Nb in the 5th period.

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

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

 Times Cited Count:10 Percentile:48.86(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

Current status of the control system for J-PARC accelerator complex

Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.

Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10

J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.

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

 Times Cited Count:132 Percentile:95.85(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

 Times Cited Count:182 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

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

 Times Cited Count:437 Percentile:99.2(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.

Oral presentation

Anion-exchange experiments of nuclear reaction products transported by He/KCl and He/KF gas-jet systems

Kasamatsu, Yoshitaka; Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Nishinaka, Ichiro; Sato, Tetsuya; Li, Z.; Kikuchi, Takahiro; Nagame, Yuichiro; et al.

no journal, , 

Radioactive nuclides of Nb and Ta were produced in the Zr/Hf(p,xn)Nb/Ta and Ge/Gd($$^{19}$$F,xn)Nb/Ta reactions at the JAEA tandem accelerator. The products were rapidly transported by He/KCl and He/KF gas-jet systems to the chemistry laboratory. It was found that the transport efficiency using the He/KF gas-jet system is comparable with that by the He/KCl gas-jet system which has been generally used. Subsequently, on-line anion-exchange experiments with the products were performed in HF/HNO$$_{3}$$ solutions. A small physical adsorption of Nb on the surfaces of the tools was observed when the KCl aerosols were used, while better reproducibility of the elution of Nb was obtained using the KF aerosols. We interpret that stable fluoro complexes of Nb are rapidly formed by using the KF aerosols and we can suggest that the He/KF gas-jet system should be used in the on-line anion-exchange experiment of the group 5 elements for the study of the fluoride complexation of the elements.

Oral presentation

Electrochemistry of the heaviest elements at JAEA

Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Kitatsuji, Yoshihiro; Ishii, Yasuo; Sato, Tetsuya; Li, Z.; Sato, Nozomi; Kikuchi, Takahiro; Nishinaka, Ichiro; et al.

no journal, , 

Oxidation of element 102, nobelium (No), using a developed electrolytic chromatography apparatus on an atom-at-a-time scale will be presented. It was found that the most stable ion, No$$^{2+}$$, is oxidized to No$$^{3+}$$ in $$alpha$$-hydroxyisobutyric acid ($$alpha$$-HIB) solution using the apparatus and that the oxidized No complex with $$alpha$$-HIB holds the trivalent state in the column above an applied potential of 1.0 V. Electrochemical reduction of element 101, mendevelium (Md) in HCl will be also presented.

Oral presentation

Chemical investigation of Rf and Db at JAEA

Nagame, Yuichiro; Asai, Masato; Ishii, Yasuo; Kikuchi, Takahiro; Li, Z.; Sato, Tetsuya; Toyoshima, Atsushi; Tsukada, Kazuaki; Kasamatsu, Yoshitaka*; Haba, Hiromitsu*; et al.

no journal, , 

no abstracts in English

Oral presentation

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

Kasamatsu, Yoshitaka*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Li, Z.; Ishii, Yasuo; Sato, Tetsuya; Nishinaka, Ichiro; Kikuchi, Takahiro; Haba, Hiromitsu*; et al.

no journal, , 

Dubnium-262 was produced in the $$^{248}$$Cm($$^{19}$$F, 5n) reaction at the JAEA tandem accelerator. Reaction products were rapidly transported by a He/KF gas-jet system to the chemistry laboratory. Anion-exchange behavior of Db in HF/HNO$$_{3}$$ solution was then investigated using the newly developed on-line ion-exchange and $$alpha$$-particle detection apparatus. Distribution coefficients of Db were clearly smaller than those of Ta, the closest homologue in the periodic table, and were close to those of lighter homologue Nb and also the pseudo homologue Pa. Fluoride complex formation of Db will be discussed.

Oral presentation

Conceptual design study and related R&Ds toward the demonstration reactor of JSFR, 5; Development of steel plate reinforced concrete containment vessel for JSFR

Kato, Atsushi; Negishi, Kazuo; Sato, Kenichiro*; Akiyama, Yo*; Hara, Hiroyuki*; Iwasaki, Mikinori*; Abe, Ganji*; Tokiyoshi, Takumi*; Okafuji, Takashi*; Umeki, Katsuhiko*; et al.

no journal, , 

Report research and development activities related to steel plate reinforced concrete containment vessel for the JSFR conducted as a part of METI commissioned research.

24 (Records 1-20 displayed on this page)