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Ca; Spectroscopy of 
K, Ca, and 
CaKoiwai, Takuma*; Wimmer, K.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Duguet, T.*; Holt, J. D.*; Miyagi, Takayuki*; Navr
til, P.*; Ogata, Kazuyuki*; et al.
Physics Letters B, 827, p.136953_1 - 136953_7, 2022/04
Times Cited Count：0no abstracts in English
Cl isotopesLinh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; G
mez-Ramos, M.*; et al.
Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10
Times Cited Count：1 Percentile：46.35(Physics, Nuclear)no abstracts in English
Ca from direct reactionsBrowne, F.*; Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Ogata, Kazuyuki*; Utsuno, Yutaka; Yoshida, Kazuki; Achouri, N. L.*; Baba, Hidetada*; Calvet, D.*; et al.
Physical Review Letters, 126(25), p.252501_1 - 252501_7, 2021/06
Times Cited Count：1 Percentile：0(Physics, Multidisciplinary)Direct proton-knockout reactions of Sc were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of Ca were investigated through 
-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological inter-nucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of Sc, valence proton removals populated predominantly the ground-state of Ca. This counter-intuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.
Ar by the (
,2) reactionJuhsz, M. M.*; Elekes, Z.*; Sohler, D.*; Utsuno, Yutaka; Yoshida, Kazuki; Otsuka, Takaharu*; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Baba, Hidetada*; et al.
Physics Letters B, 814, p.136108_1 - 136108_8, 2021/03
Times Cited Count：1 Percentile：46.35(Astronomy & Astrophysics)The nuclear structure of Ar was studied by the (,2) reaction using -ray spectroscopy for the bound and unbound states. Comparing the results to our shell-model calculations, two bound and six unbound states were established. The low cross sections populating the two bound states of Ar could be interpreted as a clear signature for the presence of significant sub-shell closures at neutron numbers 32 and 34 in argon isotopes.
= 32 shell closure below calcium; Low-lying structure of 
ArCort
s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Menndez, J.*; Ogata, Kazuyuki*; Schwenk, A.*; Shimizu, Noritaka*; Simonis, J.*; et al.
Physical Review C, 102(6), p.064320_1 - 064320_9, 2020/12
Times Cited Count：4 Percentile：65.18(Physics, Nuclear)Low-lying excited states in the = 32 isotope Ar were investigated by in-beam -ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a 3
state. The level scheme built using coincidences was compared to shell-model calculations in the 
model space and to 
predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to 2
states, while the previously proposed 4
state could also correspond to a 2 state.
= 40 isotones towards 
Ca; First spectroscopy of 
TiCorts, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Menndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.
Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01
Times Cited Count：19 Percentile：96.74(Astronomy & Astrophysics)Excited states in the = 40 isotone Ti were populated via the 
V(,
)Ti reaction at 
200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using -ray spectroscopy. The energies of the 
and 
transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring 
Cr and 
Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.
Ca corroborates arising 
neutron magic numberChen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navrtil, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.
Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10
Times Cited Count：32 Percentile：93.02(Physics, Multidisciplinary)no abstracts in English
Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：7 Percentile：63.57(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Iwasa, Kazuaki*; Iga, Fumitoshi*; Moyoshi, Taketo*; Nakao, Akiko*; Ohara, Takashi
Journal of the Physical Society of Japan, 87(6), p.064705_1 - 064705_5, 2018/06
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)Kuchitsu, Takashi*; Tachikawa, Masanori*; Shiga, Motoyuki
Chemical Physics Letters, 433(1-3), p.193 - 198, 2006/12
Times Cited Count：1 Percentile：2.6(Chemistry, Physical)A new approach to electron dynamics in molecular system is developed, which combines molecular orbital (MO) scheme and Gaussian wave packet dynamics. The time-dependent electronic wavefunction is described by the linear combination of atomic orbitals (LCAO) using frozen-width floating Gaussian wave packet basis functions. The equations of motion for the time-dependent variables, such as the LCAO coefficients, the Gaussian centers, and their phase factors of the respective basis function, are determined based on time-dependent variational principle. This technique is demonstrated for the attosecond propagation of electronic wavefunction of hydrogen and helium atoms in response to electrostatic field.
Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi*; Watanabe, Kazuhiro; Imai, Tsuyoshi
Review of Scientific Instruments, 75(5), p.1764 - 1766, 2004/05
Times Cited Count：7 Percentile：40.53(Instruments & Instrumentation)Negative ion beams of high current density are required for accelerator and fusion. The H source utilizes surface production that produces H from H or H. And hence, high proto yield ion source is required. Generally, a large volume plasma generator with strong plasma confinement is suitable to achieve high proton yield. On the contrary, production of high proton ratio plasma is not easy in small sources. However, in a small source (3.5 liter), high current H beam of 800 A/m
was obtained. In this research, the proton ratio was investigated experimentally and analytically in a small source (1.4 liter). The measured proton ratio increased form 40% to 90% by applying the magnetic filter. From the numerical analysis, the proton ratio is low as 40% in the driver region. However, with the magnetic filter, flow of primary electrons is restrained, resulting in suppression of H
production at the extraction region. In addition, molecular ions are easily destroyed by thermal electrons in the filter region. Thus the proton ratio is enhanced by the magnetic field in the small sources.
Inoue, Takashi; Hanada, Masaya; Iga, Takashi*; Imai, Tsuyoshi; Kashiwagi, Mieko; Kawai, Mikito; Morishita, Takatoshi; Taniguchi, Masaki; Umeda, Naotaka; Watanabe, Kazuhiro; et al.
Fusion Engineering and Design, 66-68, p.597 - 602, 2003/09
Times Cited Count：21 Percentile：79.65(Nuclear Science & Technology)The neutral beam (NB) injection has been one of the most promising methods for plasma heating and current drive in tokamak fusion devices. JAERI has developed high energy electrostatic accelerators for the NB systems in JT-60U and ITER. Recent progress on this R&D are as follows: 1) In the JT-60U NB system, some of the beams has been deflected due to distorted electric field in the accelerator, resulting in an excess heat load on the NB port. By correcting the electric field, a continuous injection of H
beam was succeeded for 10 s with the NB power of 2.6 MW at 355 keV. 2) To increase the beam energy, a metal structure called stress ring was designed. The ring reduces electric field concentration at the triple junction point (interface between metal and dielectric insulator inside vacuum). Initial test of the accelerators with the stress rings has shown higher voltage hold off performance in both accelerators for JT-60U and ITER R&D than that without rings.
Taniguchi, Masaki; Hanada, Masaya; Iga, Takashi*; Inoue, Takashi; Kashiwagi, Mieko; Morishita, Takatoshi; Okumura, Yoshikazu; Shimizu, Takashi; Takayanagi, Tomohiro; Watanabe, Kazuhiro; et al.
Nuclear Fusion, 43(8), p.665 - 669, 2003/08
Times Cited Count：15 Percentile：45.64(Physics, Fluids & Plasmas)no abstracts in English
Watanabe, Kazuhiro; Iga, Takashi*; Morishita, Takatoshi; Kashiwagi, Mieko; Inoue, Takashi; Hanada, Masaya; Taniguchi, Masaki; Imai, Tsuyoshi
Proceedings of 28th Linear Accelerator Meeting in Japan, p.186 - 188, 2003/08
no abstracts in English
Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi*; Watanabe, Kazuhiro; Kashiwagi, Mieko; Shimizu, Takashi; Taniguchi, Masaki; Hanada, Masaya; Imai, Tsuyoshi
JAERI-Tech 2003-007, 16 Pages, 2003/03
JAERI-Tech-2003-007.pdf:1.28MB
Recently the ion source for IFMIF (International Fusion Material Irradiation facility) achieved positive ion beams of 120 mA with the proton ratio of 90% by applying magnetic filter even in a small ion source. The mechanism of a high proton ration plasma production in such a small ion source has not been studied. Molecular ions are destroyed and the proton is produced from the dissociation of molecular ions in the filter region. Thus the proton yield is enhanced even in the small volume discharge. Using the same numerical method, the plasma production was calculated for the large ion source. The high proton ratio can be easily obtained, where the contribution of proton production by the ionization of H becomes high. From the negative ion production point of view, the negative ion beam current was numerically evaluated. The high atom flux to the plasma grid generates the large amount of negative ions rather than that by the positive ions in Cs-seeded large ion sources.
Shimizu, Takashi; Morishita, Takatoshi; Kashiwagi, Mieko; Hanada, Masaya; Iga, Takashi*; Inoue, Takashi; Watanabe, Kazuhiro; Wada, Motoi*; Imai, Tsuyoshi
JAERI-Tech 2003-006, 26 Pages, 2003/03
JAERI-Tech-2003-006.pdf:1.12MB
no abstracts in English
Morishita, Takatoshi; Iga, Takashi*; Inoue, Takashi; Imai, Tsuyoshi; Kashiwagi, Mieko; Shimizu, Takashi; Taniguchi, Masaki; Hanada, Masaya; Watanabe, Kazuhiro
Dai-1-Kai 21-Seiki Rengo Shimpojiumu; Kagaku Gijutsu To Ningen Rombunshu, p.221 - 224, 2002/11
A high proton ratio (
90%) and a high current density proton beam is demanded in the International Fusion Materials Irradiation Facility (IFMIF). In the development of the beam source for nuclear fusion, it was indicated that the enhancement of the ion confinement using the large ion source is suitable for the increase in the proton ratio. In the beam source for accelerators, a single beamlet is enough to obtain a certain beam current, therefore, a small ion source is suitable from the aspect of efficiency and simplification of the system. To obtain the high proton ratio beam from the small ion source, it is necessary to grasp the production mechanism of proton. Then, the production process of the proton in the small ion source was investigated using rate equations. Obtained results were compared with experimental results. Consequently, although the proton is mainly produced from the molecular positive ions as considered conventionally, the production of the high proton ratio beam is also possible in the small ion source due to the effects of the magnetic filter.
Taniguchi, Masaki; Hanada, Masaya; Iga, Takashi*; Inoue, Takashi; Kashiwagi, Mieko; Morishita, Takatoshi; Okumura, Yoshikazu; Shimizu, Takashi*; Takayanagi, Tomohiro*; Watanabe, Kazuhiro; et al.
Proceedings of 19th IAEA Fusion Energy Conference (FEC 2002) (CD-ROM), 5 Pages, 2002/10
A high power neutral beam injector (NBI) has been designed for ITER. A key component of the NBI system is a high power beam source which produces a 40A D ion beams at the energy of 1 MeV. JAERI has developed a vacuum insulated beam source (VIBS). The VIBS insulates the high voltage of 1 MV by immersing the ion source and accelerator in vacuum. So far the VIBS succeeded in acceleration of 37 mA (power supply drain current) beam up to 970 keV for 1 s. The achieved beam energy is nearly equal to the required value for the ITER NBI system. The negative ion source for the ITER beam source has been also developed. One of the key issues for the negative ion source is reduction of the operating pressure. By optimizing the filter magnetic field for negative ion production even at low pressure, a H ion beam of 31 mA/cm was extracted at 0.1 Pa. Although the pulse length was very short (0.1 s) the ITER requirement on the current density was demonstrated at 1/3 of the ITER design pressure (0.3 Pa), which could reduce the heat loading on the accelerator grids.
Watanabe, Kazuhiro; Amemiya, Toru*; Hanada, Masaya; Iga, Takashi*; Imai, Tsuyoshi; Inoue, Takashi; Kashiwagi, Mieko; Kuriyama, Masaaki; Morishita, Takatoshi; Okumura, Yoshikazu; et al.
Review of Scientific Instruments, 73(2), p.1090 - 1092, 2002/02
Times Cited Count：18 Percentile：66.61(Instruments & Instrumentation)no abstracts in English
/D) ion beams in negative ion source development for NBIKashiwagi, Mieko; Amemiya, Toru*; Iga, Takashi*; Inoue, Takashi; Imai, Tsuyoshi; Okumura, Yoshikazu; Takayanagi, Tomohiro; Hanada, Masaya; Fujiwara, Yukio; Morishita, Takatoshi; et al.
Dai-12-Kai Ryushisen No Sentanteki Oyo Gijutsu Ni Kansuru Shimpojiumu (BEAMS 2001) Hobunshu, p.37 - 40, 2001/11
no abstracts in English
