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Journal Articles

Design and beam dynamics studies of an ADS RFQ based on an equipartitioned beam scheme

Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Nakano, Keita; Maekawa, Fujio; Meigo, Shinichiro; Jameson, R. A.*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.499 - 502, 2023/01

The Japan Atomic Energy Agency (JAEA) is designing a 30-MW proton linear accelerator (linac) for the accelerator-driven subcritical system (ADS). The Radio Frequency Quadrupole (RFQ) is an essential component for the performance of high-intensity linac, especially in ADS, where stringent reliability is demanded. The present RFQ will capture a 20 mA proton beam and accelerate from the energy of 35 keV to 2.5 MeV, where the space-charge effects are severe. The present RFQ's design employs the equipartitioning (EP) beam scheme to control the emittance growth and compactness. As a result, the beam halo formation was minimized and allowed to optimize the superconducting linac downstream part. A remarkable feature of this RFQ is the low Kilpatrick factor of 1.2 adopted to achieve high stability by reducing the probability of surface sparking on the vane. This work presents and discusses the results of this RFQ design.

Journal Articles

Fine structure in the decay of $^{223}$ U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

https://doi.org/10.1016/j.physletb.2019.135096

Times Cited Count：11 Percentile：78.75(Astronomy & Astrophysics)

Journal Articles

Large ferroquadrupole moment induced in the octupole-ordered Ce $_{0.7}$ La $_{0.3}$ B revealed by high-resolution X-ray diffraction

Inami, Toshiya; Michimura, Shinji*; Hayashi, Yuya*; Matsumura, Takeshi*; Sera, Masafumi*; Iga, Fumitoshi*

Physical Review B, 90(4), p.041108_1 - 041108_5, 2014/07

https://doi.org/10.1103/PhysRevB.90.041108

Times Cited Count：9 Percentile：38.66(Materials Science, Multidisciplinary)

We carried out a high-resolution X-ray diffraction experiment on Ce $_{0.7}$ La $_{0.3}$ B. This compound exhibits antiferro-octupole order (AFO) below = 1.4 K, and it is theoretically suggested that ferroquadrupole moments and a resultant rhombohedral deformation are induced in the AFO phase. We observe the splitting of Bragg reflections below and find that the unit cell is rhombohedral with the elongated [111] axis. We also precisely evaluate the magnitude of the induced quadrupole moments from the obtained shear strain and find that the quadrupole moments are not reduced in the AFO phase.

Journal Articles

Multipole ordering in -electron systems on the basis of a - coupling scheme

Kubo, Katsunori; Hotta, Takashi

Physical Review B, 72(14), p.144401_1 - 144401_12, 2005/10

https://doi.org/10.1103/PhysRevB.72.144401

Times Cited Count：30 Percentile：72.75(Materials Science, Multidisciplinary)

We investigate microscopic aspects of multipole ordering in -electron systems with emphasis on the effect of lattice structure. For the purpose, we construct -electron models on three kinds of lattices, simple cubic (sc), bcc, and fcc, in a tight-binding approximation on the basis of a - coupling scheme. Then, an effective model is derived in the strong-coupling limit for each lattice with the use of second-order perturbation theory with respect to . By applying mean-field theory to such effective models, we find multipole ordered states depending on the lattice structure. For the sc lattice, a $Gamma_{3g}$ antiferro-quadrupole transition occurs at a finite temperature and at further lowering temperature, we find another transition to a ferromagnetic state. For the bcc lattice, a $Gamma_{2u}$ antiferro-octupole ordering occurs first, and then, a ferromagnetic phase transition follows it. Finally, for the fcc lattice, we find a single phase transition to the longitudinal triple- $Gamma_{5u}$ octupole ordering.

Journal Articles

Direct observation of quadrupolar excitons in the heavy-fermion superconductor PrOsSb

Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Metoki, Naoto; Raymond, S.*; Masson, M.-A.*; Flouquet, J.*; Sugawara, Hitoshi*; Aoki, Yuji*; et al.

Physical Review Letters, 95(10), p.107003_1 - 107003_4, 2005/09

https://doi.org/10.1103/PhysRevLett.95.107003

Times Cited Count：96 Percentile：92.11(Physics, Multidisciplinary)

We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOsSb $_{12}$ . The observed excitation clearly softens at a wave vector = (1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at = (1,0,0) is smaller than that around the zone center. This result directly evidences that this excitonic behavior is derived mainly from nonmagnetic quadrupolar interactions. Furthermore, the narrowing of the linewidths of the excitations below the superconducting transition temperature indicates the close connection between the superconductivity and the excitons.

Journal Articles

Multiple coulomb excitation experiment of $^{68}$ Zn

Koizumi, Mitsuo; Seki, Akiyuki*; Toh, Yosuke; Osa, Akihiko; Utsuno, Yutaka; Kimura, Atsushi; Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi; Katakura, Junichi; et al.

Nuclear Physics A, 730(1-2), p.46 - 58, 2004/01

https://doi.org/10.1016/j.nuclphysa.2003.10.010

Times Cited Count：20 Percentile：72.49(Physics, Nuclear)

Coulomb excitation experiment was carried out with a $^{68}$ Zn beam bombarding a $^{nat}$ Pb target. Two matrix elements and the quadrupole moment of the 2 $_{1}$ $^{+}$ state were newly derived with the least-squares search code GOSIA. The potential energy surface (PES) was calculated with the Nilsson-Strutinsky model, showing two shallow minima: the first minimum does not contain the $1g_{9/2}$ orbit below the Fermi surface, while the second minimum does. The ground state band and the intruder band seem to be constructed on the first and the second minimum, respectively. As for the ground state band, the asymmetric rotor model and the IBM in O(6) limit reproduced the experimental values rather well. The shallow PES may suggest unstability of the shape. The ground state band structure may be explained assuming a soft triaxial deformation.

Journal Articles

Quadrupole and hexadecapole ordering in DyBC; Direct observation with resonant X-ray diffraction

Tanaka, Yoshikazu*; Inami, Toshiya; Lovesey, S. W.*; Knight, K. S.*; Yakhou, F.*; Mannix, D.*; Kokubun, Jun*; Kanazawa, Masayuki*; Ishida, Kotaro*; Nanao, Susumu*; et al.

Physical Review B, 69(2), p.024417_1 - 024417_11, 2004/01

https://doi.org/10.1103/PhysRevB.69.024417

Times Cited Count：36 Percentile：79.54(Materials Science, Multidisciplinary)

Direct evidence of the spatial ordering of Dy 4 quadrupole and hexadecapole moments in DyBC is demonstrated by resonant X-ray diffraction enhanced by an electric quadrupole event (2 resonance) at the Dy L $_{III}$ absorption edge. The diffraction data show that the structural phase transition at $_{Q}$ = 24.7 K is accompanied by a reduction in the symmetry of the Dy site to 2/, from 4/, and the spatial ordering of the time-even Dy multipoles with A $_{g}$ character. Below $_{Q}$ the crystal structure is described by the space group 4/ and Dy ions occupy sites (4). The distortion at T $_{Q}$ involves the lattice occupied by B and C ions, and it amounts to a buckling of B-C planes that are normal to the two-fold rotation axis of 2/. An immediately plausible model of low-energy Dy states correlates data on the specific heat, our X-ray diffraction signals, and magnetic ordering below 15.3 K which has been observed in magnetic neutron diffraction.

Journal Articles

Multiple Coulomb Excitation Experiment of $^{66}$ Zn

Koizumi, Mitsuo; Seki, Akiyuki*; Toh, Yosuke; Oshima, Masumi; Osa, Akihiko; Kimura, Atsushi; Hatsukawa, Yuichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Matsuda, Makoto; et al.

European Physical Journal A, 18(1), p.87 - 92, 2003/10

https://doi.org/10.1140/epja/i2003-10063-9

Times Cited Count：16 Percentile：68.41(Physics, Nuclear)

no abstracts in English

Journal Articles

Interference between thomson scattering and resonant scattering in X-ray diffraction from CeB $_{6}$

Nagao, Tatsuya*; Igarashi, Junichi

Journal of the Physical Society of Japan, 72(9), p.2381 - 2384, 2003/09

https://doi.org/10.1143/JPSJ.72.2381

Times Cited Count：10 Percentile：54.95(Physics, Multidisciplinary)

We examine the mechanism of the X-ray diffraction process by including the Thomson scattering (TS) term in addition to the resonant X-ray scattering (RXS) term near the Ce L absorption edge in the antiferroquadrupole (AFQ) ordering phase of CeB $_{6}$ . Assuming the AFQ order in the 4f states but without any lattice distortion, we obtain the TS intensity comparable to the RXS intensity, owing to the anisotropic charge distribution of 4f states. The present calculation reproduces well the interference pattern between the TS and RXS terms for the (5/2,3/2,3/2) spot observed in the recent experiment. The result suggests that the TS signal as well as the main peak of the RXS signal are a direct reflection of the AFQ order in CeB $_{6}$ .

Journal Articles

Design of a focusing high-energy heavy ion microbeam system at the JAERI AVF cyclotron

Oikawa, Masakazu*; Kamiya, Tomihiro; Fukuda, Mitsuhiro; Okumura, Susumu; Inoue, Hiromitsu*; Masuno, Shinichi*; Umemiya, Shinsuke*; Oshiyama, Yoshifumi*; Taira, Yutaka*

Nuclear Instruments and Methods in Physics Research B, 210(1-4), p.54 - 58, 2003/09

https://doi.org/10.1016/S0168-583X(03)01007-3

Times Cited Count：25 Percentile：82.86(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Mechanism of resonant X-ray scattering in DyB $_{2}$ C $_{2}$

Nagao, Tatsuya*; Igarashi, Junichi

Physica B; Condensed Matter, 329-333(Part2), p.628 - 630, 2003/05

https://doi.org/10.1016/S0921-4526(02)02531-0

Times Cited Count：5 Percentile：31.4(Physics, Condensed Matter)

For elucidating the relation between the resonant X-ray scattering (RXS) signal and the orbital order, we calculate the RXS spectra near the Dy L $_{III}$ absorption edge in DyB $_{2}$ C $_{2}$ , in the antiferro-quadrupole (AFQ) ordering phase. Using a microscopic model that the 4f states of Dy are atomic while the 5d states form an energy band with a reasonable density of states, we obtain sufficient RXS intensities on the AFQ superlattice spot assuming the quadrupole order in the 4f states but without any lattice distortion, in good agreement with the recent experiment. The present result demonstrates the mechanism that the intensity is brought about by the modulation of 5d states through the anisotropic term of the 5d-4f Coulomb interaction.

Journal Articles

First measurement of the quadrupole moment in the 2 state of $^{84}$ Kr

Osa, Akihiko; Czosnyka, T.*; Utsuno, Yutaka; Mizusaki, Takahiro*; Toh, Yosuke; Oshima, Masumi; Koizumi, Mitsuo; Hatsukawa, Yuichi; Katakura, Junichi; Hayakawa, Takehito; et al.

Physics Letters B, 546(1-2), p.48 - 54, 2002/10

https://doi.org/10.1016/S0370-2693(02)02660-6

Times Cited Count：10 Percentile：51.1(Astronomy & Astrophysics)

A $^{84}$ Kr beam was Coulomb-excited on a $^{98}$ Mo target and a $^{nat}$ Ta target. Six reduced matrix elements for 5 low-lying states were derived from the analysis using the least-squares code GOSIA. The quadrupole moment of the 2 was newly obtained. The measured quadrupole moment and the values are consistent with large-scale shell-model calculations which give a systematic description of ,=,50 isotones.