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Journal Articles

Status quo of the injector for the IFMIF/EVEDA prototype accelerator

Shinto, Katsuhiro; Ichikawa, Masahiro; Takahashi, Yasuyuki*; Kubo, Takashi*; Tsutsumi, Kazuyoshi; Kikuchi, Takayuki; Kasugai, Atsushi; Sugimoto, Masayoshi; Gobin, R.*; Girardot, P.*; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1009 - 1012, 2014/10

The prototype accelerator is being developed as an engineering validation for the International Fusion Materials Irradiation Facility (IFMIF) equipped with an accelerator-driven-type neutron source for developing fusion reactor materials. This prototype accelerator is a deuteron linear accelerator consisting of an injector, an RFQ, a superconducting linac and their auxiliaries. It aims to produce a CW D$$^+$$ beam with the energy and current of 9 MeV/125 mA. The injector test was completed at CEA/Saclay in 2012 for producing a CW H$$^+$$ beam and a CW D$$^+$$ beam with the energy and current of 100 keV/140 mA. After the beam test at CEA/Saclay, the injector was transported to the International Fusion Energy Research Centre (IFERC) located in Rokkasho, Aomori, Japan. In the end of 2013, installation of the injector was started at IFERC for the injector beam test beginning from summer 2014 in order to obtain better beam qualities to be satisfied with the injection and acceleration of the following accelerators. In this paper, some results of the injector beam test performed at CEA/Saclay and the status quo of the installation of the injector at IFERC are presented.

Journal Articles

Formation of NaCl-type monodeuteride LaD by the disproportionation reaction of LaD$$_{2}$$

Machida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi*; Oshita, Hidetoshi*; et al.

Physical Review Letters, 108(20), p.205501_1 - 205501_5, 2012/05

 Times Cited Count:10 Percentile:58.4(Physics, Multidisciplinary)

Hydrogen atoms absorbed in a metal occupy the interstitial sites of the metal lattice. In an fcc metal lattice, each metal atom has two tetrahedral (T) and one octahedral (O) sites that can accommodate hydrogen. Rare-earth metal La forms T-site occupied LaH$$_2$$ and fully occupied LaH$$_3$$. O-site occupied or NaCl-type monohydride has yet to be reported for rare-earth metals. Previous X-ray diffraction measurements revealed the pressure-induced decomposition of an fcc-LaH$$_{2.3}$$ into H-rich and H-poor phases around 11 GPa. The present neutron diffraction measurements on LaD$$_{2}$$ confirm the formation of NaCl-type LaD as a counterpart of the D-rich LaD$$_{2+delta}$$ by disproportionation. First-principle calculations demonstrate that the NaCl-type LaH is stabilized at high pressures. Finding the NaCl-type LaH will pave the way for investigations on the site-dependent nature of hydrogen-metal interactions.

Journal Articles

Production and decay properties of $$^{264}$$Hs and $$^{265}$$Hs

Sato, Nozomi; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Kaji, Daiya*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sumita, Takayuki*; Yoneda, Akira*; et al.

Journal of the Physical Society of Japan, 80(9), p.094201_1 - 094201_7, 2011/09

 Times Cited Count:11 Percentile:61.11(Physics, Multidisciplinary)

Decay properties of $$^{264}$$Hs and $$^{265}$$Hs produced in the $$^{207,208}$$Pb($$^{58}$$Fe, $$xn$$) [$$x$$=1, 2] reactions were studied using a gas-filled recoil ion separator at the linear accelerator facility of RIKEN. A total of 6 decay chains were assigned to $$^{264}$$Hs. Cross sections for the $$^{264}$$Hs production in the $$^{208}$$Pb($$^{58}$$Fe,$$2n$$) and $$^{207}$$Pb($$^{58}$$Fe,$$n$$) reactions were measured to be $$2.8^{+6.5}_{-2.3}$$pb and $$6.9^{+4.4}_{-3.1}$$pb, respectively. The isotope $$^{264}$$Hs decayed with a half-life of $$0.751^{+0.518}_{-0.218}$$ms by $$alpha$$-particle emission and spontaneous fission. The $$alpha$$-particle energy of $$^{264}$$Hs was observed at 10.61$$pm$$0.04 and 10.80$$pm$$0.08 MeV. The spontaneous fission branch of $$^{264}$$Hs was found to be $$17^{+38}_{-14}%$$.

Journal Articles

Electronic structure of lithium amide

Kamakura, Nozomu; Takeda, Yukiharu; Saito, Yuji; Yamagami, Hiroshi; Tsubota, Masami*; Paik, B.*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kato, Yukako*; et al.

Physical Review B, 83(3), p.033103_1 - 033103_4, 2011/01

 Times Cited Count:5 Percentile:27.56(Materials Science, Multidisciplinary)

The electronic structure of lithium amide, which is lightweight complex hydride expected as a high-capacity hydrogen storage material, is investigated by N 1$$s$$ soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The overall feature of the electronic structure of lithium amide by the XES and XAS is consistent with the band calculation, while the strongly hybridized state with H 1$$s$$ is located at higher binding energy than the band calculation.

Journal Articles

Determination of silicon vacancy in ion-beam synthesized $$beta$$-FeSi$$_{2}$$

Maeda, Yoshihito; Ichikawa, Takayuki*; Jonishi, Takafumi*; Narumi, Kazumasa

Physics Procedia, 11, p.83 - 86, 2011/00

 Times Cited Count:0 Percentile:0.01

Journal Articles

Effect of hydrogenation on the electronic state of metallic La hydrides probed by X-ray absorption sectroscopy at the La $$L$$-edges

Ishimatsu, Naoki*; Sasada, Ryohei*; Maruyama, Hiroshi*; Ichikawa, Takayuki*; Miyaoka, Hiroki*; Kimura, Toru*; Tsubota, Masami*; Kojima, Yoshitsugu*; Tsumuraya, Takao*; Oguchi, Tamio*; et al.

Journal of Physics; Conference Series, 190, p.012070_1 - 012070_4, 2009/11

 Times Cited Count:4 Percentile:77.5

We have investigated the effect of hydrogenation on La $$5d$$ and $$6p$$ electronic states in metallic LaH$$_x$$ by X-ray absorption near edge structure at the La $$L$$-edges. As the hydrogen content $$x$$ increases from 0 to 2.6, white-line intensity at the La $$L_{2,3}$$-edges shows a remarkable increase in the range of $$x$$ $$>$$ 2.0. This is interpreted as the increase in La $$5d$$ hole induced by interstitial H atoms on the octahedral sites. On the other hand, the shoulder structure at the La $$L_1$$-edge disappears in the process of $$x$$ = 0.0 $$rightarrow$$ 2.0, indicating that the $$p$$-$$ d$$ hybridization is weakened by H atoms on the tetrahedral sites. This study demonstrates that H atoms on the two interstitial H sites provide different contribution to the modification of the electronic states.

Journal Articles

Decay properties of $$^{266}$$Bh and $$^{262}$$Db produced in the $$^{248}$$Cm + $$^{23}$$Na reaction

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi*; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

Journal of the Physical Society of Japan, 78(6), p.064201_1 - 064201_6, 2009/06

 Times Cited Count:27 Percentile:78.3(Physics, Multidisciplinary)

Decay properties of an isotope $$^{266}$$Bh and its daughter nucleus $$^{262}$$Db produced by the $$^{248}$$Cm($$^{23}$$Na,5$$n$$) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. $$^{266}$$Bh was clearly identified from the correlation of the known nuclide, $$^{262}$$Db. The obtained decay properties of $$^{266}$$Bh and $$^{262}$$Db are consistent with those observed in the $$^{278}$$113 chain, which provided further confirmation of the discovery of $$^{278}$$113.

Journal Articles

Production of a new hassium isotope $$^{263}$$Hs

Kaji, Daiya*; Morimoto, Koji*; Sato, Nozomi*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Ozeki, Kazutaka*; Haba, Hiromitsu*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; et al.

Journal of the Physical Society of Japan, 78(3), p.035003_1 - 035003_2, 2009/03

A new hassium isotopes $$^{263}$$Hs is directly produced for the first time. The experiment was performed at the linear accelerator (RILAC) facility in RIKEN (the Institute of Physical and Chemical Research) from Jun. 19 to 25. In the 25-h irradiation of $$^{58}$$Fe on $$^{206}$$Pb and 46-h irradiation of $$^{56}$$Fe on $$^{208}$$Pb, 8 decay chains and 1 decay chain, respectively, were observed. All decay chains were assigned to subsequent decays from $$^{263}$$Hs. The half-life of $$^{263}$$Hs is 0.60$$^{+0.30}_{-0.15}$$ ms. In this experiment, the total beam dose was $$4.1times10^{17}$$ ions for $$^{58}$$Fe and $$6.2times10^{17}$$ ions for $$^{56}$$Fe. The production cross section corresponding to 8 decay events and 1 decay chain was deduced to be 21$$^{+10}_{-8}$$ pb and 1.6$$^{+3.7}_{-1.3}$$ pb by assuming that the transmission of the system is 80%.

Journal Articles

Production and decay properties of $$^{263}$$Hs

Kaji, Daiya*; Morimoto, Koji*; Sato, Nozomi*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Ozeki, Kazutaka*; Haba, Hiromitsu*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; et al.

Journal of the Physical Society of Japan, 78(3), p.035003_1 - 035003_2, 2009/03

 Times Cited Count:3 Percentile:27.63(Physics, Multidisciplinary)

A new neutron deficient hassium ($$Z$$=108) isotope of $$^{263}$$Hs was identified via two different reactions of $$^{206}$$Pb($$^{58}$$Fe,n) and $$^{208}$$Pb($$^{56}$$Fe,n) by using a gas-filled recoil separator GARIS at June 2008. During the 25-h irradiation of $$^{206}$$Pb with the $$^{58}$$Fe beam and 46-h irradiation of $$^{208}$$Pb with the $$^{56}$$Fe beam, 8 decay chains and 1 decay chain, respectively, have been observed. The half-life of $$^{263}$$Hs is 0.60$$^{+0.30}_{0.15}$$ ms. In this experiment, the total beam doses of the Fe and $$^{56}$$Fe was 4.1$$times$$10$$^{17}$$ ions and 6.2$$times$$10$$^{17}$$ ions, respectively. The production cross sections corresponding to the 8 decay chains and 1 decay chain have been deduced to be 21$$^{+10}_{-8}$$ pb and 1.6$$^{+3.7}_{-1.3}$$ pb by assuming the transmission of the system to be 80%.

Journal Articles

New decay properties of $$^{264}$$Hs, $$^{260}$$Sg, and $$^{256}$$Rf

Sato, Nozomi*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Kaji, Daiya*; Koura, Hiroyuki; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozawa, Akira*; et al.

RIKEN Accelerator Progress Report, Vol.42, P. 16, 2009/00

New Decay Properties of $$^{264}$$Hs and its $$alpha$$-decay daughter nuclei were studied by using reactions of $$^{208}$$Pb($$^{58}$$Fe,2n) and $$^{207}$$Pb($$^{58}$$Fe,n) by using a gas-filled recoil ion separator, GARIS at RIKEN. We observed three correlated events in irradiation of $$^{58}$$Fe on $$^{208}$$Pb, and eight events in irradiation of $$^{58}$$Fe on $$^{207}$$Pb. A half-life was deduced to be 0.90$$^{+0.40}_{-0.20}$$. We assigned these eleven events to be the decays of $$^{264}$$Hs. We found different decay-chain events of $$^{264}$$Hs from a previous report. One is a long-lived $$alpha$$-decay of $$^{260}$$Sg with 180$$^{150}_{-60}$$ms of half-life. Another is a long-lived $$alpha$$-decay of $$^{256}$$Rf with 10.4$$^{8.4}_{-3.2}$$s of half-life. For $$^{260}$$Sg and $$^{256}$$Rf, the decay of such a long-lived state have not been reported. These are the first observations of isomerism in $$^{260}$$Sg and $$^{256}$$Rf.

JAEA Reports

Analysis on the fuel cycle requirements of the FR systems

Maki, Takashi*; Ichikawa, Hajime*; Asao, Takayuki*; Horiuchi, Nobutake*

JNC TJ9400 2002-004, 228 Pages, 2001/02

JNC-TJ9400-2002-004.PDF:9.97MB

We developed two computer codes to evaluate fuel cycle requirements of FR systems, which were selected in "the feasibility studies on commercialized FBR cycle systems". One code (CODE for material balance analysis) is to calculate the material balance data to evaluate the characteristics of each candidate. The other is to calculate the time-series data of material balance of fuel cycle as a whole, to evaluate an optimum scenario of FR systems introduction. The main characteristics of these codes are as follows: (1) Common function of both codes (a) They execute burn up calculation using characteristics values of reactor calculated with ORIGEN2 code. And they adjust Pu content using a concept of physical accounting method for adjusted fissile enrichment. (b) They simulate 18 type of FR systems, 10 reactor types and 6 reprocessing types. (2) Function of CODE for material balance analysis (a) It calculates nuclide inventory and thermal power, radioactivity, radio-toxicity in the waste and environmental release. (b) It evaluates safety of geological disposal of HLW and TRU waste (iodine waste) with simplified safety estimation method. (3) Function of CODE for time-series analysis (a) In addition to FR systems, it simulates 4 type of LWR systems and 5 type of Pu-Thermal LWR systems. (b)It calculates the Pu demand-and-supply situation. The precision of these codes was checked and verified by using other code result. Then we investigation characteristics of each FR system by evaluating material balance of fuel cycle. In addition we clarified differences between scenarios of introduction of FR systems.

Oral presentation

Productions and decay properties of $$^{264,265}$$Hs

Sato, Nozomi; Kaji, Daiya*; Morimoto, Koji*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; Ozeki, Kazutaka*; et al.

no journal, , 

In this work, the production and decay properties of $$^{264,265}$$Hs produced in the $$^{208}$$Pb($$^{58}$$Fe, $$xn$$) [$$x = 1,2$$] and $$^{207}$$Pb($$^{58}$$Fe, $$n$$) reactions were investigated. The experiment was performed at the RILAC facility in RIKEN. The evaporation residues (ERs) were separated from the primary beam with the gas-filled recoil ion separator, GARIS. In the focal plane of GARIS the products were implanted into a position-sensitive Si detector for measuring the arrival of ERs and subsequent $$alpha$$-decays or spontaneous fission from ERs. We have measured production cross-sections of $$^{264,265}$$Hs in the $$^{58}$$Fe + $$^{208}$$Pb reaction at several bombarding energies. For the $$^{208}$$Pb($$^{58}$$Fe, $$n$$)$$^{265}$$Hs reaction, the cross-section maximum of ($$51^{+46}_{-29}$$) pb was obtained at the bombarding energy of 220.5 MeV at the middle of the target. For even-even nucleus $$^{264}$$Hs, we have also observed accurate decay data with good statistics.

Oral presentation

Productions and decay properties of a new isotope of $$^{263}$$Hs

Kaji, Daiya*; Morimoto, Koji*; Sato, Nozomi; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; Ozeki, Kazutaka*; et al.

no journal, , 

A new neutron deficient hassium ($$Z=108$$) isotope of $$^{263}$$Hs was identified via two different reactions of $$^{206}$$Pb($$^{58}$$Fe,$$n$$) and $$^{208}$$Pb($$^{56}$$Fe,$$n$$) by using the gas-filled recoil separator GARIS. During irradiation of $$^{206}$$Pb with the $$^{58}$$Fe beam and irradiation of $$^{208}$$Pb with the $$^{56}$$Fe beam, 8 decay chains and 1 decay chain, respectively, were observed. The properties of decay events obtained by irradiation of $$^{58}$$Fe on $$^{206}$$Pb match well with those by irradiation of $$^{56}$$Fe on $$^{208}$$Pb. The mean $$alpha$$-decay energies for the 3 groups are 10.82, 10.55, and 10.37 MeV, respectively. The half-life of $$^{263}$$Hs is determined to be 0.60 ms.

Oral presentation

Production and decay properties of $$^{266}$$Bh and its daughter nuclei

Morimoto, Koji*; Morita, Kosuke*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

no journal, , 

A nuclide, $$^{266}$$Bh, is the great-grand-daughter of $$^{278}$$113 that is produced in the $$^{209}$$Bi + $$^{70}$$Zn reaction. The identification was based on a genetic link to the known daughter nucleus $$^{262}$$Db by alpha-decays. The main purpose of this work is to provide further confirmation of the production and identification of the isotope $$^{278}$$113. As a present result, a state in $$^{266}$$Bh, which decays by an alpha emission with the energies ranging from 9.05 to 9.23 MeV, feeds a state in $$^{262}$$Db, which decays by alpha emission and by SF with a previously known half-life. The result provided a further confirmation of the production and identification of the isotope of the 113th element, $$^{278}$$113, studied by a research group at RIKEN.

Oral presentation

Production and decay properties of $$^{266}$$Bh and its daughter nuclei

Morimoto, Koji*; Morita, Kosuke*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

no journal, , 

no abstracts in English

Oral presentation

Productions and decay properties of a new isotope of $$^{263}$$Hs

Kaji, Daiya*; Morimoto, Koji*; Sato, Nozomi; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; Ozeki, Kazutaka*; et al.

no journal, , 

no abstracts in English

Oral presentation

Soft X-ray emission spectroscopy of SrFeO$$_{2}$$

Mizumaki, Masaichiro*; Agui, Akane; Uozumi, Takayuki*; Inoue, Akira*; Kawai, Masanori*; Ichikawa, Noriya*; Shimakawa, Yuichi*

no journal, , 

no abstracts in English

Oral presentation

Production and decay properties of $$^{263,264,265}$$Hs

Sato, Nozomi; Kaji, Daiya*; Morimoto, Koji*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; Ozeki, Kazutaka*; et al.

no journal, , 

In the superheavy nuclei region, the deformed proton shell at $$Z=108$$ and neutron shells at $$N=152$$ and 162 have been found. $$^{260}$$Hs with $$Z=108$$ and $$N=152$$ is expected to be the doubly deformed magic nuclei, however, decay properties of $$^{260}$$Hs and its neighboring nuclei is not well known. In order to approach $$^{260}$$Hs, we synthesized $$^{263,264,265}$$Hs by $$^{208}$$Pb($$^{58}$$Fe,xn) [$$x=1, 2$$], $$^{207}$$Pb($$^{58}$$Fe,n), $$^{206}$$Pb($$^{58}$$Fe,n), $$^{208}$$Pb($$^{56}$$Fe,n) reactions. The experiment was performed with the gas-filled recoil ion separator GARIS at the linear accelerator facility in RIKEN. In this work, 9 $$alpha$$-decay events of $$^{263}$$Hs were observed with half-life $$T_{1/2}=0.60^{+0.30}_{-0.15}$$ ms and $$alpha$$-decay energy $$Q_{alpha}=10.99$$ MeV. For $$^{264}$$Hs, we have also observed new $$alpha$$-particle energy, 10.65 MeV. $$Q_{alpha}$$ values of $$^{263,264,265}$$Hs isotopes increase with decreasing neutron number.

Oral presentation

Confirmations of the synthesis of $$^{278}$$113 produced by the $$^{209}$$Bi($$^{70}$$Zn,n)$$^{278}$$113 reaction

Morimoto, Koji*; Morita, Kosuke*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

no journal, , 

We performed the experiment to synthesize an isotope of the element 113 produced by a $$^{209}$$Bi($$^{70}$$Zn,n)$$^{278}$$113 reaction using a gas-filled recoil ion separator (GARIS) at RIKEN. Two decay chains were observed, and assigned to those originating from an isotope $$^{278}$$113. Both chains were connected into the previously known decays of $$^{266}$$Bh and $$^{262}$$Db via previously unknown decays of $$^{278}$$113, $$^{274}$$Rg, and $$^{270}$$Mt. Although the $$^{266}$$Bh was known nuclide, a number of atoms reported so far was limited. In order to study more precise decay property of the $$^{266}$$Bh, we performed the direct production of $$^{266}$$Bh by the $$^{248}$$Cm($$^{23}$$Na,5n)$$^{266}$$Bh reaction. In this experiment, the $$^{266}$$Bh was clearly identified from the correlation of the nuclide, $$^{262}$$Db. The obtained decay properties of $$^{266}$$Bh and $$^{262}$$Db are consistent with those observed in the $$^{278}$$113 chain, which provided further confirmation of the discovery of $$^{278}$$113.

Oral presentation

Observation of the electronic excitation structure for SrFeO$$_{2}$$ by using a soft X-ray emission spectroscopy

Mizumaki, Masaichiro*; Agui, Akane; Uozumi, Takayuki*; Ichikawa, Noriya*; Shimakawa, Yuichi*

no journal, , 

no abstracts in English

32 (Records 1-20 displayed on this page)