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Fujita, Manami; Hasegawa, Shoichi; Hosomi, Kenji; Ichikawa, Masaya; Ichikawa, Yudai; Kim, S.; Nanamura, Takuya; Sako, Hiroyuki; Tamura, Hirokazu; Yamamoto, Takeshi; et al.
Progress of Theoretical and Experimental Physics (Internet), 2022(12), p.123D01_1 - 123D01_17, 2022/12
Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)Nanamura, Takuya; Fujita, Manami; Hasegawa, Shoichi; Ichikawa, Masaya; Ichikawa, Yudai; Imai, Kenichi*; Naruki, Megumi; Sato, Susumu; Sako, Hiroyuki; Tamura, Hirokazu; et al.
Progress of Theoretical and Experimental Physics (Internet), 2022(9), p.093D01_1 - 093D01_35, 2022/09
Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Progress of Theoretical and Experimental Physics (Internet), 2022(9), p.093D03_1 - 093D03_37, 2022/09
Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)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:0 Percentile:0.01(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.
Shobuda, Yoshihiro
Progress of Theoretical and Experimental Physics (Internet), 2022(5), p.053G01_1 - 053G01_44, 2022/05
Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)When the skin depth is greater than the chamber thickness for relativistic beams, the two-dimensional longitudinal resistive-wall impedance of a cylindrical chamber with a finite thickness decreases proportionally to the frequency. The phenomenon is commonly interpreted as electro-magnetic fields leaking out of the chamber over a frequency range. However, the relationship between the wall current on the chamber and the leakage fields from the chamber is unclear because the naive resistive-wall impedance formula does not dynamically express how the wall current converts to the leakage fields when the skin depth exceeds the chamber thickness. A prestigious textbook {Kheifets} re-expressed the resistive-wall impedance via a parallel circuit model with the resistive-wall and inductive terms to provide a dynamic picture of the phenomenon. However, there are some flaws in the formula. From a fundamental standpoint, this study highlights them and provides a more appropriate and rigorous picture of the longitudinal resistive-wall impedance with finite thickness. To demonstrate their physical meaning, we re-express the longitudinal impedance for non-relativistic beams, as well as the transverse resistive-wall impedance including space charge impedance based on a parallel circuit model.
Yoshimoto, Masahiro*; Fujita, Manami; Hashimoto, Tadashi; Hayakawa, Shuhei; Ichikawa, Yudai; Ichikawa, Masaya; Imai, Kenichi*; Nanamura, Takuya; Naruki, Megumi; Sako, Hiroyuki; et al.
Progress of Theoretical and Experimental Physics (Internet), 2021(7), p.073D02_1 - 073D02_19, 2021/07
Times Cited Count:6 Percentile:77.07(Physics, Multidisciplinary)Shimizu, Noritaka*; Togashi, Tomoaki*; Utsuno, Yutaka
Progress of Theoretical and Experimental Physics (Internet), 2021(3), p.033D01_1 - 033D01_15, 2021/03
Times Cited Count:3 Percentile:57.66(Physics, Multidisciplinary)no abstracts in English
Yuasa, Takayuki*; Wada, Yuki*; Enoto, Teruaki*; Furuta, Yoshihiro; Tsuchiya, Harufumi; Hisadomi, Shohei*; Tsuji, Yuna*; Okuda, Kazufumi*; Matsumoto, Takahiro*; Nakazawa, Kazuhiro*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2020(10), p.103H01_1 - 103H01_27, 2020/10
Times Cited Count:10 Percentile:74.3(Physics, Multidisciplinary)Kou, E.*; Tanida, Kiyoshi; Belle II Collaboration*; 537 of others*
Progress of Theoretical and Experimental Physics (Internet), 2020(2), p.029201_1 - 029201_6, 2020/02
Times Cited Count:148 Percentile:100(Physics, Multidisciplinary)Kou, E.*; Tanida, Kiyoshi; Belle II Collaboration*; 537 of others*
Progress of Theoretical and Experimental Physics (Internet), 2019(12), p.123C01_1 - 123C01_654, 2019/12
Times Cited Count:291 Percentile:99.97(Physics, Multidisciplinary)Sonoda, Tetsu*; Katayama, Ichiro*; Wada, Michiharu*; Iimura, Hideki; Sonnenschein, V.*; Iimura, Shun*; Takamine, Aiko*; Rosenbusch, M.*; Kojima, Takao*; Ahn, D. S.*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(11), p.113D02_1 - 113D02_12, 2019/11
Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)An in-flight separator, BigRIPS, at RIBF in RIKEN provides each experiment with specific nuclides separated from many nuclides produced by projectile fragmentation or in-flight fission. In this process, nuclides other than separated ones are discarded on the slits in BigRIPS, although they include many nuclides interested from the view point of nuclear structure. In order to extract these nuclides for parasitic experiments, we are developing a method using laser ion-source (PALIS). A test experiment with Se beam from RIBF has been performed by using a gas cell set in BigRIPS. Unstable nuclides around
Se were stopped in the gas cell in accordance with a calculation using LISE code. The stopping efficiency has been estimated to be about 30%. As a next step, we will establish the technique for extracting reaction products from the gas cell.
Ekawa, Hiroyuki; Ashikaga, Sakiko; Hasegawa, Shoichi; Hashimoto, Tadashi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji*; Nanamura, Takuya; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02
Times Cited Count:19 Percentile:83.3(Physics, Multidisciplinary)Theint, A. M. M.*; Ekawa, Hiroyuki; Yoshida, Junya; 7 of others*
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D01_1 - 021D01_10, 2019/02
Times Cited Count:6 Percentile:54.46(Physics, Multidisciplinary)Hagiwara, Kaito*; Yano, Takatomi*; Das, P. K.*; Lorenz, S.*; Ou, Iwa*; Sakuda, Makoto*; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Harada, Hideo; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.023D01_1 - 023D01_26, 2019/02
Times Cited Count:23 Percentile:86.68(Physics, Multidisciplinary)Shobuda, Yoshihiro
Progress of Theoretical and Experimental Physics (Internet), 2018(12), p.123G01_1 - 123G01_52, 2018/12
Times Cited Count:1 Percentile:13.51(Physics, Multidisciplinary)For an accurate calculation of the resistive-wall impedance of a resistive chamber, we must know the conductivity of a resistive material. The conductivity of the material at a given frequency can be evaluated by measuring the -matrix of a propagation mode in a waveguide. However, in most cases, only the absolute value of the
-matrix is used for evaluation under the assumption that the conductivity is pure real, although both the
-matrix and the conductivity are complex numbers in general. To evaluate complex conductivity from a measured complex
-matrix, we derive new theoretical formulae of the
-matrix for the TE
and TM
modes of a waveguide and for the quasi-TEM
mode of a coaxial waveguide, where complex conductivity is assumed. In a reverse way, we can determine the conductivity of a material by using it as a fitting parameter in a comparison of a measured
-matrix with those obtained using theoretical formulae. The three independent methods facilitate triple-checking of the accuracy of the measured conductivity.
Shimizu, Nobuhiro*; Tanida, Kiyoshi; Belle Collaboration*; 169 of others*
Progress of Theoretical and Experimental Physics (Internet), 2018(2), p.023C01_1 - 023C01_26, 2018/02
Times Cited Count:5 Percentile:45.82(Physics, Multidisciplinary)Shobuda, Yoshihiro; Chin, Y. H.*
Progress of Theoretical and Experimental Physics (Internet), 2017(12), p.123G01_1 - 123G01_22, 2017/12
Times Cited Count:5 Percentile:44.55(Physics, Multidisciplinary)no abstracts in English
Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*
Progress of Theoretical and Experimental Physics (Internet), 2017(11), p.113G01_1 - 113G01_24, 2017/11
Times Cited Count:2 Percentile:23.18(Physics, Multidisciplinary)Two proton bunches circulates the accelerator ring in the J-PARC 3GeV synchrotoron (RCS). The accelerating voltage is also generated in twice of the revolution frequency. The major Fourier component of the wake voltage should become even harmonics. However, the odd harmonics grow and cause a large number of beam loss. The beam measurement suggests that the odd harmonic wake voltages promote oscillations of not only the bunch position but also the bunch shape. The oscillations continue because they amplify the odd harmonic beam components. A particle tracking simulation can reproduce these simultaneous oscillations. It is found that the odd harmonic wake voltages lead to severe rf bucket distortion that results in beam loss. As a result, introducing a beam loading compensation system for the minor harmonics can prevent the beam loss and it would contribute the stable accelerator operation with the reduction of the activation.
Harada, Hiroyuki; Saha, P. K.; Tamura, Fumihiko; Meigo, Shinichiro; Hotchi, Hideaki; Hayashi, Naoki; Kinsho, Michikazu; Hasegawa, Kazuo
Progress of Theoretical and Experimental Physics (Internet), 2017(9), p.093G01_1 - 093G01_16, 2017/09
Times Cited Count:2 Percentile:23.18(Physics, Multidisciplinary)The 3 GeV rapid cycling synchrotron (RCS) of the J-PARC is a high intensity proton accelerator of 1 MW. The accelerated proton beams in the RCS are extracted by eight pulsed kicker magnets and are delivered to a materials and life science experimental facility and main ring synchrotron. However, the fields of the magnets experience ringing that displaces the position of the extracted beam. This is a major issue from the viewpoint of target integrity and large beam loss. The ringing was directly measured as the displacement of the extracted beams by using a shorter pulsed beam and scanning the entire trigger timing of the kickers. We managed to cancel out the ringing by optimizing trigger timing and achieved the beam extraction with high accuracy. We developed automatic correction system of the timing and now have a higher stability. In this paper, we report our procedure and experimental results for ringing compensation.
Shobuda, Yoshihiro; Chin, Y. H.*; Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Irie, Yoshiro*; Tamura, Fumihiko; Tani, Norio; Toyama, Takeshi*; Watanabe, Yasuhiro; et al.
Progress of Theoretical and Experimental Physics (Internet), 2017(1), p.013G01_1 - 013G01_39, 2017/01
Times Cited Count:12 Percentile:67.74(Physics, Multidisciplinary)The Rapid Cycling Synchrotron (RCS), whose beam energy ranges from 400 MeV to 3 GeV and which is located in the Japan Proton Accelerator Research Complex, is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Contrary to conventional understanding, we have succeeded to accelerate a 1-MW equivalent beam. The machine has some interesting features: for instance, the beam tends to be unstable for the smaller transverse beam size, the beam is stabilized by increasing the peak current . Space charge effects play an important role in the beam instability at the RCS. In this study, a new theory has been developed to calculate the beam growth rate with the head-tail and coupled-bunch modes (
) while taking space charge effects into account. The theory sufficiently explains the distinctive features of the beam instabilities at the RCS.