Development of a single-ended magnetic alloy loaded cavity in the Japan Proton Accelerator Research Complex rapid cycling synchrotron

Yamamoto, Masanobu; Nomura, Masahiro; Okita, Hidefumi; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*

Progress of Theoretical and Experimental Physics (Internet), 2023(7), p.073G01_1 - 073G01_16, 2023/07

https://doi.org/10.1093/ptep/ptad085

The Japan Proton Accelerator Research Complex (J-PARC) Rapid Cycling Synchrotron (RCS) employs Magnetic Alloy (MA) loaded cavities. We realize multi-harmonic rf driving and beam loading compensation owing to the broadband characteristics of the MA. The currently installed cavity is the conventional type one which is designed to be driven by tube amplifiers in a push-pull operation. The push-pull operation has some advantages, i.e., suppressing a higher harmonic distortion without the beam acceleration and shortening the cavity length. However, a disadvantage arises at the high intensity beam acceleration where the multi-harmonic rf driving causes a severe imbalance of the anode voltage swing and restricts the tube operation. Although we have achieved an acceleration for the design beam power of 1 MW, the imbalance becomes an issue to further increase the beam power. We have developed a single-ended MA cavity to avoid such difficulty. The cavity has no tube imbalance intrinsically and it is found that the power consumption to drive the cavity can be reduced compared with the conventional one.

Inverse mass ordering of light scalar mesons in the Nambu-Jona-Lasinio model

Saionji, Takahiro*; Jido, Daisuke*; Harada, Masayasu*

Progress of Theoretical and Experimental Physics (Internet), 2023(3), p.033D01_1 - 033D01_18, 2023/03

https://doi.org/10.1093/ptep/ptad028

Measurement of differential cross sections for elastic scattering in the momentum range 0.44-0.80 GeV/c

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

https://doi.org/10.1093/ptep/ptac101

Beam emittance growth due to the strong space-charge field at low energy of a high-intensity ion linac and its mitigation using an octupole magnetic field

Chimura, Motoki; Harada, Hiroyuki; Kinsho, Michikazu

Progress of Theoretical and Experimental Physics (Internet), 2022(6), p.063G01_1 - 063G01_26, 2022/06

https://doi.org/10.1093/ptep/ptac077

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.

Role of the axial anomaly in the chiral susceptibility of QCD at high temperature

Aoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*; Suzuki, Kei

Progress of Theoretical and Experimental Physics (Internet), 2022(2), p.023B05_1 - 023B05_12, 2022/02

https://doi.org/10.1093/ptep/ptac001

The chiral susceptibility, or the first derivative of the chiral condensate with respect to the quark mass, is often used as a probe for the QCD phase transition since the chiral condensate is an order parameter of symmetry breaking. However, the chiral condensate also breaks the axial symmetry, which is usually not studied as it is already broken by the anomaly and apparently has little impact on the transition. We investigate the susceptibilities in the scalar and pseudoscalar channels in order to quantify how much the axial breaking contributes to the chiral phase transition. Employing a chirally symmetric lattice Dirac operator and its eigenmode decomposition, we separate the axial breaking effects from others. Our result in two-flavor QCD indicates that both of the connected and disconnected chiral susceptibilities are dominated by axial breaking at temperatures MeV after the quadratically divergent constant is subtracted.

Gamow-Teller transitions of neutron-rich = 82, 81 nuclei by shell-model calculations

Shimizu, Noritaka*; Togashi, Tomoaki*; Utsuno, Yutaka

Progress of Theoretical and Experimental Physics (Internet), 2021(3), p.033D01_1 - 033D01_15, 2021/03

AA2020-0889.pdf:1.07MB

https://doi.org/10.1093/ptep/ptab022

no abstracts in English

Erratum; The Belle II physics book

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

https://doi.org/10.1093/ptep/ptaa008

Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for high-energy RI beams in the parasitic gas cell

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

AA2019-0315.pdf:1.37MB

https://doi.org/10.1093/ptep/ptz120

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.

Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

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

https://doi.org/10.1093/ptep/pty149

Gamma-ray spectrum from thermal neutron capture on gadolinium-157

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

https://doi.org/10.1093/ptep/ptz002