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Journal Articles

Rail deployment operation test for ITER blanket handling system with positioning misalignment

Takeda, Nobukazu; Aburadani, Atsushi; Tanigawa, Hisashi; Shigematsu, Soichiro; Kozaka, Hiroshi; Murakami, Shin; Kakudate, Satoshi; Nakahira, Masataka; Tesini, A.*

Fusion Engineering and Design, 88(9-10), p.2186 - 2189, 2013/10

 Times Cited Count:2 Percentile:21.27(Nuclear Science & Technology)

R&D for rail deployment equipment was performed for the ITER blanket remote handling system. The target torque for the automatic operation was investigated. The result shows that the 20% of the rated torque is adequate as the torque limitation for the automatic operation. A schedule for the procurement of the blanket remote handling system, which will be delivered to the ITER in 2020, was also shown.

Journal Articles

Performance evaluation on force control for ITER blanket installation

Aburadani, Atsushi; Takeda, Nobukazu; Shigematsu, Soichiro; Murakami, Shin; Tanigawa, Hisashi; Kakudate, Satoshi; Nakahira, Masataka*; Hamilton, D.*; Tesini, A.*

Fusion Engineering and Design, 88(9-10), p.1978 - 1981, 2013/10

 Times Cited Count:2 Percentile:21.27(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Comparative study of laser and TIG weldings for application to ITER blanket hydraulic connection

Tanigawa, Hisashi; Aburadani, Atsushi; Shigematsu, Soichiro; Takeda, Nobukazu; Kakudate, Satoshi; Mori, Seiji*; Jokinen, T.*; Merola, M.*

Fusion Engineering and Design, 87(7-8), p.999 - 1003, 2012/08

 Times Cited Count:13 Percentile:74.08(Nuclear Science & Technology)

This paper presents results of R&D activities where the laser and TIG welding tools were developed to apply the blanket hydraulic connection. The target pipe is 48.26 mm in outer diameter and 2.77 mm-thick. A single path welding without filler materials is required to reduce the weld heat input related to re-weldability. For the laser welding, the focal spot diameter was expanded to increase allowable misalignment. The TIG welding tool was equipped with AVC (Arc Voltage Control) to avoid a torch sticking and to enlarge allowable misalignment. For each tool, the welding conditions were optimized for all position welding to horizontally located pipes. Obtained parameters such as the weld heat input, allowable misalignment, lifetime of the tools and amount of sputter and fume, were comparatively assessed.

Journal Articles

Verification test results of a cutting technique for the ITER blanket cooling pipes

Shigematsu, Soichiro; Tanigawa, Hisashi; Aburadani, Atsushi; Takeda, Nobukazu; Kakudate, Satoshi; Mori, Seiji*; Nakahira, Masataka*; Raffray, R.*; Merola, M.*

Fusion Engineering and Design, 87(7-8), p.1218 - 1223, 2012/08

 Times Cited Count:5 Percentile:42.85(Nuclear Science & Technology)

The current design of the ITER blanket system is a modular configuration and a total of 440 blanket modules are to be installed in the ITER vacuum vessel. Each blanket module consists of the first wall (FW) and the shield block (SB). The FW receives a high heat load from the plasma. The SB shields components from the neutrons generated by the nuclear fusion reaction. The FW will be damaged by the heat load and neutrons, so it requires scheduled replacement. For the FW replacement, cutting/welding tools for the cooling pipes must be able to conduct the following operations: access and cut/weld the pipe from the inside of the cooling pipe. The cutting tool for the pipe end is required to cut flat plate circularly from the surface side of the FW. This paper describes the current status of R&D of the cutting tools for maintenance of the cooling pipe of the FW.

Journal Articles

Observation of high-$$j$$ quasiparticle states in $$^{249}$$Cm by in-beam $$gamma$$-ray spectroscopy using heavy-ion transfer reactions

Ishii, Tetsuro; Makii, Hiroyuki*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shigematsu, Soichiro*; Kaneko, Junichi*; Shizuma, Toshiyuki; et al.

Physical Review C, 78(5), p.054309_1 - 054309_11, 2008/11

 Times Cited Count:14 Percentile:67.09(Physics, Nuclear)

Journal Articles

In-beam $$gamma$$-ray spectroscopy of neutron-rich nuclei in the uranium region through the heavy-ion transfer reaction

Ishii, Tetsuro; Makii, Hiroyuki; Asai, Masato; Koura, Hiroyuki; Shigematsu, Soichiro*; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; et al.

Nuclear Physics A, 805(1-4), p.257 - 259, 2008/06

no abstracts in English

Journal Articles

One-quasiparticle bands in neutron-rich $$^{187}$$W

Shizuma, Toshiyuki; Ishii, Tetsuro; Makii, Hiroyuki*; Hayakawa, Takehito; Matsuda, Makoto; Shigematsu, Soichiro*; Ideguchi, Eiji*; Zheng, Y.*; Liu, M.*; Morikawa, Tsuneyasu*; et al.

Physical Review C, 77(4), p.047303_1 - 047303_4, 2008/04

 Times Cited Count:8 Percentile:52.37(Physics, Nuclear)

Modest spin states in neutron-rich $$^{187}$$W have been populated using a $$^{186}$$W($$^{18}$$O,$$^{17}$$O) one-neutron transfer reaction. While negative-parity bands previously known are extended to higher spin, two positive-parity bands are newly identified. Configurations based on $$nu$$ i$$_{13/2}$$ orbitals are assigned to these bands from an analysis of the level energy systematics as well as the g-factors derived from in-band branching ratios.

Journal Articles

Z dependence of the $$N = 152$$ deformed shell gap; In-beam $$gamma$$-ray spectroscopy of neutron-rich $$^{245, 246}$$Pu

Makii, Hiroyuki; Ishii, Tetsuro; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; Tome, Hayato*; Ichikawa, Shinichi; et al.

Physical Review C, 76(6), p.061301_1 - 061301_5, 2007/12

 Times Cited Count:26 Percentile:83.64(Physics, Nuclear)

We have measured deexcitation $$gamma$$ rays for the first time in the neutron-rich nuclei of $$^{246}$$Pu$$_{152}$$ and $$^{245}$$Pu$$_{151}$$ produced by the ($$^{18}$$O, $$^{16}$$O) and the ($$^{18}$$O, $$^{17}$$O) reactions, respectively. The ground-state band of $$^{246}$$Pu was established up to 12$$^{+}$$ states. The systematics of the moments of inertia of $$_{94}$$Pu isotopes suggests that the $$N = 152$$ deformed subshell closure disappears in these isotopes. The measurements of deexcitation $$gamma$$ rays in $$^{245}$$Pu shows a small energy spacing between neutron orbitals at $$N = 152$$, which explans the disappearance of the subshell closure.

Journal Articles

Evidence for a $$K^pi=1/2^+$$ isomer in neutron-rich $$^{185}$$Ta

Shizuma, Toshiyuki; Ishii, Tetsuro; Makii, Hiroyuki; Hayakawa, Takehito; Shigematsu, Soichiro*; Matsuda, Makoto; Ideguchi, Eiji*; Zheng, Y.*; Liu, M.*; Morikawa, Tsuneyasu*

European Physical Journal A, 34(1), p.1 - 4, 2007/10

 Times Cited Count:6 Percentile:47.33(Physics, Nuclear)

Excited states in neutron-rich $$^{185}$$Ta have been populated following the one-proton pickup reaction of $$^{186}$$W($$^{18}$$O,$$^{19}$$F). In-beam $$gamma$$ rays were measured in coincidence with scattered particles detected by a high-resolution $$Delta E$$-$$E$$ Si telescope for reaction channel selection. Several low-lying levels including a $$T_{1/2}=0.9(3)$$ $$mu$$s isomer at 406 keV have been identified. A spin assignment of $$I=3/2$$ and the 1/2$$^+$$[411] Nilsson configuration are given to the isomer in comparison with the level energy systematics and the isomer decay rates in the region.

Journal Articles

In-beam $$gamma$$-ray study of the neutron-rich nuclei of $$^{240}$$U, $$^{246}$$Pu, and $$^{250}$$Cm produced by the ($$^{18}$$O, $$^{16}$$O) reaction

Ishii, Tetsuro; Shigematsu, Soichiro*; Makii, Hiroyuki; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; Kaneko, Junichi*; et al.

Physics of Atomic Nuclei, 70(8), p.1457 - 1461, 2007/08

 Times Cited Count:9 Percentile:58.39(Physics, Nuclear)

We have measured deexcitation $$gamma$$ rays in the neutron-rich nuclei of $$^{240}$$U, $$^{246}$$Pu and $$^{250}$$Cm. These nuclei were produced by the ($$^{18}$$O, $$^{16}$$O) two-neutron transfer reactions with a 200, 162 and 162 MeV $$^{18}$$O beams and a $$^{238}$$U, $$^{244}$$Pu and $$^{248}$$Cm targets, respectively, using the tandem accelerator at Tokai, Japan. The $$gamma$$ rays in residual nuclei were measured by taking coincidence with scattering particles using Si $$Delta E$$-$$E$$ detectors. We have identified $$gamma$$ rays in $$^{240}$$U, $$^{246}$$Pu and $$^{250}$$Cm by selecting the kinetic energies of $$^{16}$$O particles which correspond to the excitation energies in these nuclei below their neutron separation energies. The ground-state bands of $$^{240}$$U, $$^{246}$$Pu and $$^{250}$$Cm were established up to 12$$^{+}$$ states and the $$K^{pi}=0^{-}$$ octupole band of $$^{240}$$U was established up to 9$$^{-}$$ state. Because the deformations of these nuclei are well developed, the moments of inertia reflect the pairing gap, which is expected to be smaller, resulting in a larger moment of inertia, at the deformed shell closure. We have found that the moment of inertia of the ground-state band of $$^{248}$$Cm$$_{152}$$ is considerably larger than that of $$^{250}$$Cm$$_{154}$$. This fact supports the existence of the deformed subshell closure at $$N=152$$ in Cm isotopes. On the other hand, the moment of inertia of $$^{246}$$Pu$$_{152}$$ was found to be smaller than that of $$^{244}$$Pu$$_{150}$$, which suggests that the deformed subshell closure at $$N=152$$ weakens or disappears in Pu isotopes. These results are consistent with the prediction by a cranking model calculation.

Journal Articles

Ground-state bands of neutron-rich $$^{236}$$Th and $$^{242}$$U nuclei and implication of spherical shell closure at $$N=164$$

Ishii, Tetsuro; Makii, Hiroyuki; Asai, Masato; Koura, Hiroyuki; Shigematsu, Soichiro*; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; et al.

Physical Review C, 76(1), p.011303_1 - 011303_5, 2007/07

 Times Cited Count:13 Percentile:67.67(Physics, Nuclear)

The ground-state bands of the neutron-rich $$^{236}$$Th and $$^{242}$$U nuclei were established up to spin 10 and 8, respectively, by in-beam $$gamma$$-ray spectroscopy using the ($$^{18}$$O, $$^{20}$$Ne) two-proton pickup reaction with a $$^{238}$$U and a $$^{244}$$Pu target. Deexcitation $$gamma$$ rays in $$^{236}$$Th and $$^{242}$$U were identified by selecting the kinetic energies of $$^{20}$$Ne using Si $$Delta E$$-$$E$$ detectors. The excitation energies of the first 2$$^{+}$$ states in U and Pu isotopes have local minima at $$N simeq 146$$, suggesting the possibility that nuclei with $$Z simeq 92$$ have a spherical shell closure of $$N=164$$. Calculation using the Koura-Yamada single-particle potential gives an energy gap of 1.8 MeV at $$N=164$$ for $$^{256}$$U.

Journal Articles

Excited states in neutron-rich $$^{188}$$W produced by an $$^{18}$$O-induced 2-neutron transfer reaction

Shizuma, Toshiyuki; Ishii, Tetsuro; Makii, Hiroyuki; Hayakawa, Takehito; Shigematsu, Soichiro; Matsuda, Makoto; Ideguchi, Eiji*; Zheng, Y.*; Liu, M.*; Morikawa, Tsuneyasu*; et al.

European Physical Journal A, 30(2), p.391 - 396, 2006/11

 Times Cited Count:12 Percentile:63.07(Physics, Nuclear)

Excited states in neutron-rich $$^{188}$$W have been populated using a $$^{186}$$W($$^{18}$$O,$$^{16}$$O) reaction. In-beam $$gamma$$ rays were measured in coincidence with scattered particles detected by a high-resolution $$Delta E$$-$$E$$ Si telescope. In this experiment, the ground state band has been identified up to $$I^pi=8^+$$. The $$gamma$$ band, the $$K^pi=2^-$$ octupole band, and a 2-quasiparticle state were also observed. The results are compared with predictions of self-consistent HFB cranking calculations and blocked-BCS multi-quasiparticle calculations.

Journal Articles

Ground-state band of the neutron-rich transuranium nucleus $$^{250}$$Cm$$_{154}$$

Ishii, Tetsuro; Shigematsu, Soichiro; Makii, Hiroyuki; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; Kaneko, Junichi*; et al.

Journal of the Physical Society of Japan, 75(4), p.043201_1 - 043201_4, 2006/04

 Times Cited Count:19 Percentile:69.9(Physics, Multidisciplinary)

The ground-state band of the neutron-rich transuranium nucleus $$^{250}$$Cm was established up to spin 12 by in-beam $$gamma$$-ray spectroscopy using the two-neutron-transfer reaction with a $$^{248}$$Cm target and a 162 MeV $$^{18}$$O beam. Deexcitation $$gamma$$ rays in $$^{250}$$Cm were identified by selecting the kinetic energies of $$^{16}$$O particles with Si $$Delta E$$-$$E$$ detectors. The moment of inertia of $$^{250}$$Cm$$_{154}$$ is considerably smaller than that of $$^{248}$$Cm$$_{152}$$, which supports the existence of the deformed subshell closure at $$N=152$$ in Cm isotopes.

Journal Articles

In-beam $$gamma$$-ray spectroscopy of $$^{240}$$U using the ($$^{18}$$O,$$^{16}$$O) reaction

Ishii, Tetsuro; Shigematsu, Soichiro; Asai, Masato; Makishima, Akiyasu*; Matsuda, Makoto; Kaneko, Junichi*; Hossain, I.*; Ichikawa, Shinichi; Kono, Toshiyuki*; Ogawa, Masao*

Physical Review C, 72(2), p.021301_1 - 021301_5, 2005/08

 Times Cited Count:19 Percentile:76.78(Physics, Nuclear)

In the two-neutron-transfer reaction of a 200-MeV $$^{18}$$O beam with a $$^{238}$$U target, deexcitation $$gamma$$ rays in a neutron-rich nucleus of $$^{240}$$U were measured. The $$gamma$$ rays in $$^{240}$$U were identified by taking coincidence with $$^{16}$$O, using Si $$Delta E$$-$$E$$ detectors. The kinetic energies of $$^{16}$$O particles allowed us to select the excitation energies of $$^{240}$$U below the neutron separation energy. The ground-state band and the $$K^{pi}=0^{-}$$ octupole band of $$^{240}$$U were established up to 12$$^{+}$$ and 9$$^{-}$$, respectively. The octupole-band head of $$^{240}$$U is higher than those of $$^{236,238}$$U by about a hundred keV, suggesting that a secondary maximum of octupole correlations exists at $$N=144-146$$ in U isotopes.

Oral presentation

In-beam $$gamma$$-ray measurement of the neutron-rich nucleus $$^{250}_{96}$$Cm$$_{154}$$

Ishii, Tetsuro; Shigematsu, Soichiro; Makii, Hiroyuki; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; Kaneko, Junichi*; et al.

no journal, , 

no abstracts in English

Oral presentation

In beam $$gamma$$-ray measurement of the neutron-rich nucleus $$^{246}$$Pu

Makii, Hiroyuki; Ishii, Tetsuro; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; Tome, Hayato; Ichikawa, Shinichi; et al.

no journal, , 

no abstracts in English

Oral presentation

In-beam $$gamma$$-ray spectroscopy of the neutron-rich $$^{236}$$Th and $$^{242}$$U nuclei produced by the ($$^{18}$$O,$$^{20}$$Ne) reaction

Ishii, Tetsuro; Makii, Hiroyuki; Asai, Masato; Shigematsu, Soichiro*; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; Tome, Hayato; et al.

no journal, , 

no abstracts in English

Oral presentation

$$gamma$$-ray spectroscopy of the neutron-rich $$^{187}$$W and $$^{188}$$W produced using transfer reactions

Shizuma, Toshiyuki; Hayakawa, Takehito; Ishii, Tetsuro; Makii, Hiroyuki; Matsuda, Makoto; Shigematsu, Soichiro*; Ideguchi, Eiji*; Zheng, Y.*; Liu, M.*; Morikawa, Tsuneyasu*; et al.

no journal, , 

no abstracts in English

Oral presentation

In-beam $$gamma$$-ray spectroscopy of neutron-rich $$^{245,246}$$Pu and properties of $$N = 152$$ deformed shell closure

Makii, Hiroyuki; Ishii, Tetsuro; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Kaneko, Junichi*; Tome, Hayato; Ichikawa, Shinichi; et al.

no journal, , 

We have measured in-beam $$gamma$$ rays in the neutron-rich $$^{246}$$Pu$$_{152}$$ and $$^{245}$$Pu$$_{151}$$ nuclei by means of $$^{244}$$Pu($$^{18}$$O, $$^{16}$$O)$$^{246}$$Pu and $$^{244}$$Pu($$^{18}$$O, $$^{17}$$O)$$^{245}$$Pu neutron transfer reactions, respectively. The ground-state band of $$^{246}$$Pu was established up to the $$12^+$$ state. The systematics of the 2$$^+$$ energies for the ground-state bands of Pu isotopes suggests that the $$N = 152$$ deformed shell closure disappears in Pu. The measurement of deexcitation $$gamma$$ rays in $$^{245}$$Pu shows a small energy spacing between the neutron orbitals at $$N = 152$$, which explains the disappearance of the shell closure.

Oral presentation

Spectroscopy of neutron-rich $$^{187,188}$$W produced in $$^{18}$$O-induced transferreactions

Shizuma, Toshiyuki; Ishii, Tetsuro; Makii, Hiroyuki; Hayakawa, Takehito; Shigematsu, Soichiro*; Matsuda, Makoto; Ideguchi, Eiji*; Zheng, Y.*; Liu, M.*; Morikawa, Tsuneyasu*; et al.

no journal, , 

Neutron-rich W-Os nuclei with $$Aapprox190$$ exhibit the various signature of nuclear collective motions such as $$gamma$$-softness, triaxiality, and a prolate-oblate shape transition. In addition, the emergence of high-$$K$$ isomers, where $$K$$ is the angular momentum projection on the nuclear symmetry axis, based on multi-quasiparticle excitation is a characteristic of nuclei in this region. The recent experimental and theoretical studies of the neutron-rich W nuclei have revealed the existence of high-$$K$$ multi-quasiparticle isomers. Here we report results from the in-beam $$gamma$$-ray spectroscopic experiments on neutron-rich $$^{187}$$W and $$^{188}$$W.

26 (Records 1-20 displayed on this page)