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Yamada, Ippei; Chimura, Motoki; Kamiya, Junichiro; Kinsho, Michikazu
Journal of Physics; Conference Series, 2687, p.072018_1 - 072018_6, 2024/01
no abstracts in English
Mori, Michiyasu; Maekawa, Sadamichi
Applied Physics Letters, 122(4), p.042202_1 - 042202_5, 2023/01
Times Cited Count：3 Percentile：81.68(Physics, Applied)Chimura, Motoki; Harada, Hiroyuki; Kinsho, Michikazu
Progress of Theoretical and Experimental Physics (Internet), 2022(6), p.063G01_1 - 063G01_26, 2022/06
Times Cited Count：1 Percentile：26.42(Physics, Multidisciplinary)In the low-energy region of a high-intensity ion linac, a strong space-charge field causes a rapid beam emittance growth over a short distance of only few meters. The beam emittance growth leads to a beam loss and the machine activation raising a serious issue for regular maintenance of the accelerator component and beam power ramp up. In this work, we studied the mechanism of beam emittance growth due to the space-charge field based on three-dimensional particle-tracking simulation and theoretical considerations. Numerical simulations done for the high-intensity linac at J-PARC shows that the nonlinear terms in the space-charge field directly cause a beam emittance growth and beam halo formation. Then, we also propose a method to mitigate the beam emittance growth by using an octupole magnetic field, which arises as one of the nonlinear terms in the space-charge field. By applying this method in the simulation, we have succeeded mitigating the beam emittance growth.
Okabe, Kota; Liu, Y.*; Otani, Masashi*; Moriya, Katsuhiro; Shibata, Takanori*; Chimura, Motoki*; Hirano, Koichiro; Oguri, Hidetomo; Kinsho, Michikazu
JPS Conference Proceedings (Internet), 33, p.011011_1 - 011011_6, 2021/03
To realize more stable operation of the J-PARC accelerators, we have a re-design plan of an MEBT1 (Medium Energy Beam Transport). At the J-PARC Linac, the MEBT1 has transverse and longitudinal beam matching section for the DTLs. However there are some locally activated spots in DTL area at the current beam power level. To reduce beam loss during a beam acceleration at the DTLs is a most important task for a stable user operation. The first thing we should do is investigation a connection between beam quality in the MEBT1 and parameters of the upstream hardware. In this presentation, we will report a high intensity beam study results at the MEBT1.
Araki, Yasufumi; Misawa, Takahiro*; Nomura, Kentaro*
Physical Review Research (Internet), 2(2), p.023195_1 - 023195_11, 2020/05
Chimura, Motoki*; Harada, Hiroyuki; Moriya, Katsuhiro; Okabe, Kota; Kinsho, Michikazu
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.728 - 732, 2019/07
The increase of space charge effect in high intensity beam causes the increase of the beam-loss. Beam loss limits beam intensity for accelerator equipment activation. Therefore, it is important to suppress the emittance growth due to the space charge effect. I focused on the low energy region in the linac where the space charge effect becomes remarkable. In order to identify the origin of the emittance growth due to the effect, a simulation was performed with a 3-D particle-in-cell simulation code, and evaluated the influence of the effects in the J-PARC medium energy beam transport line (MEBT1) entrance to DTL exit. As a result, it was confirmed that distortion of phase space distribution occurred due to nonlinear space charge force and that leading to emittance growth. I proposed to suppress the emittance growth by using an octupole magnet that gives nonlinear force to the beam. We report the new method and simulation results.
At revealed by in-source laser spectroscopyBarzakh, A. E.*; Cubiss, J. G.*; Andreyev, A. N.; Seliverstov, M. D.*; Andel, B.*; Antalic, S.*; Ascher, P.*; Atanasov, D.*; Beck, D.*; Biero
, J.*; et al.
Physical Review C, 99(5), p.054317_1 - 054317_9, 2019/05
Times Cited Count：12 Percentile：76.6(Physics, Nuclear)Sato, Yuki; Murakami, Hiroyuki*; Shimaoka, Takehiro*; Tsubota, Masakatsu*; Kaneko, Junichi*
Nuclear Instruments and Methods in Physics Research A, 834, p.218 - 222, 2016/10
Times Cited Count：3 Percentile：28.09(Instruments & Instrumentation)Sato, Yuki; Murakami, Hiroyuki*; Shimaoka, Takehiro*; Tsubota, Masakatsu*; Kaneko, Junichi*
Japanese Journal of Applied Physics, 55(4), p.046401_1 - 046401_5, 2016/04
Times Cited Count：4 Percentile：19.82(Physics, Applied)We investigated the performance of a charged particle detector fabricated using single-crystal diamond grown by chemical vapor deposition. The detector was able to identify four different 
Am 
-particle energies (5.389, 5.443, 5.486, and 5.545 MeV) because of its superior intrinsic energy resolution of 
0.4% (full width at half maximum). The charge collection efficiency inside the diamond crystal was 98% for both electrons and holes. The diamond detector also exhibited no significant degradation in terms of pulse height spectra and energy resolution during operation for more than 100 h in the case of mainly electron drift inside the diamond crystal. In contrast, the shapes of the pulse height spectra measured under hole drift condition deteriorated due to the polarization phenomenon.
Okabe, Kota; Maruta, Tomofumi*; Hotchi, Hideaki; Saha, P. K.; Yoshimoto, Masahiro; Miura, Akihiko; Liu, Y.*; Kinsho, Michikazu
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.933 - 937, 2015/09
In a high power proton accelerator such as the 3-GeV rapid cycle synchrotron (RCS), small ratio of the beam loss such as beam halo can cause serious radiation dose. The suppression of the transverse beam halo is a key issue to provide high intensity beam for routine user operation at the RCS. If the transverse twiss parameter of the injection beam is not matched to the RCS optics, it will generates beam halo during the multi-turn injection. In order to suppress such beam halo, twiss parameters and dispersion matching are performed at the RCS injection point. In the beam matching process, we use the rms envelope equation solver with space charge effect to predict high intensity beam behavior. The beam profile measurement is done with wire scanner monitors at the downstream of the L3BT as well as multi-wire profile monitors at the RCS injection section. In this presentation, we introduce the transverse twiss parameter matching scheme at the RCS injection points.
Kitatsuji, Yoshihiro
Bunseki, 2015(6), p.239 - 244, 2015/06
Electrochemical studies of ion transfer and charge transfer at liquid/liquid interface reported between 2012 and 2014 were surveyed. They were categorized by method of measurement. The merit of the method, improvement, species of application were described. Applied research such as analyses of redox inactive species, sensitive analyses based on adsorption at the interface and developments of new functional materials had been widely carried out.
Pastuovi
, 
*; Capan, I.*; Cohen, D.*; Forneris, J.*; Iwamoto, Naoya*; Oshima, Takeshi; Siegele, R.*; Hoshino, Norihiro*; Tsuchida, Hidekazu*
Nuclear Instruments and Methods in Physics Research B, 348, p.233 - 239, 2015/04
Times Cited Count：7 Percentile：51.03(Instruments & Instrumentation)Onishi, Hiroaki; Hotta, Takashi
AIP Conference Proceedings 850, p.1075 - 1076, 2006/09
We investigate the ground-state property of a 
-orbital Hubbard model on a triangular lattice at electron density 5.5 by using numerical techniques. There appears several types of paramagnetic phases, but we observe in common that one or two orbitals among three orbitals become relevant due to the effect of orbital ordering. It is found that charge stripe stabilized by the nearest-neighbor Coulomb interaction consists of antiferromagnetic/ferro-orbital chains for small Hund's coupling, while there occurs stripe charge ordering with ferromagnetic/antiferro-orbital chains for large Hund's coupling.
Chiba, Atsuya; Saito, Yuichi; Narumi, Kazumasa
JAEA-Review 2005-001, TIARA Annual Report 2004, p.343 - 345, 2006/01
no abstracts in English
Moribayashi, Kengo
Journal of Plasma and Fusion Research SERIES, Vol.7, p.150 - 153, 2006/00
no abstracts in English
Oshima, Takeshi; Sato, Takahiro; Oikawa, Masakazu*; Onoda, Shinobu; Hirao, Toshio; Ito, Hisayoshi
Materials Science Forum, 527-529, p.1347 - 1350, 2006/00
Charge induced in 6H-SiC pn diodes by oxygen ion microbeams was examined in an energy range between 6 and 18 MeV. To minimize the influence of damage, single ion hit Transient Ion Beam Induced Current (TIBIC) measurement system, in which the transient current induced by single ion incidence can be measured, was used in this study. The value of charge increases with increasing reverse applied bias, and the saturation of charge is observed when the depletion layer becomes longer than ion range. An increase of collected charge by the funneling effect (the generation of a transient electric filed) is observed in the case of the depletion layer shorter than ion range. The charge collection efficiency is estimated to be 100 % in the saturation region (the depletion layer longer than ion range). It strongly suggests that high quality particle detectors are fabricated using SiC.
CaMnO
(=Ho, Er, Tm, Yb and Lu)Yoshii, Kenji; Abe, Hideki*; Ikeda, Naoshi*
Journal of Solid State Chemistry, 178(12), p.3615 - 3623, 2005/12
Times Cited Count：25 Percentile：67.28(Chemistry, Inorganic & Nuclear)no abstracts in English
Laird, J. S.; Hirao, Toshio; Onoda, Shinobu; Ito, Hisayoshi
IEEE Transactions on Nuclear Science, 52(5), p.1504 - 1512, 2005/10
Times Cited Count：7 Percentile：44.84(Engineering, Electrical & Electronic)no abstracts in English
Ichikawa, Takatoshi; Iwamoto, Akira
Physical Review C, 71(6), p.067601_1 - 067601_4, 2005/06
Times Cited Count：0 Percentile：0.01(Physics, Nuclear)We estimate the decrease of the Coulomb-barrier height between colliding parters due to charge polarizations in the entrance channel for cold-fusion reactions. Since the Coulomb-repulsion force increases with increasing the proton numbers of the target and projectile such as cold-fusion reactions, it is expected that the charge distribution of the colliding nuclei is changed to some extent. The resulting charge distribution induced by this polarization decreases the interacting Coulomb energy between the colliding partners, whereas their own self energies increase due to the increase of the symmetry energy. We assume that the resulting charge displacements between protons and neutrons are the sum of the surface- and volume-charge components and estimate the extent of the charge polarization with the self energy on the basis of the droplet model. We show the difference between the charge polarization of light and heavy nuclei and the decrease of the Coulomb barrier height for synthesizing superheavy elements.
p diodes using transient ion beam-induced currentOshima, Takeshi; Sato, Takahiro; Oikawa, Masakazu*; Yamakawa, Takeshi; Onoda, Shinobu; Wakasa, Takeshi; Laird, J. S.; Hirao, Toshio; Kamiya, Tomihiro; Ito, Hisayoshi; et al.
Nuclear Instruments and Methods in Physics Research A, 541(1-2), p.236 - 240, 2005/04
Times Cited Count：9 Percentile：55.92(Instruments & Instrumentation)In order to develop particle detectors based on SiC semiconductor, SiC pn-diodes were irradiated with microbeam of 15MeV oxygen ions. The transient current was measured using the single ion hit transient ion beam induced current (TIBIC) system at TIARA. As the results, peak intensity of transient current induded by ion irradiation increased and falltime decreased with increasing applied bias. By the integration of transient current, the charge collection was estimated. It was found that charges generated in deeper region beyond the depletion layer can be collected by the funneling effect.
