Progress of evaluation of beam coupling impedance reduction for the Eddy-current type septum magnet in J-PARC MR

Kobayashi, Aine*; Toyama, Takeshi*; Nakamura, Takeshi*; Shobuda, Yoshihiro; Ishii, Koji*; Tomizawa, Masahito*; Takeuchi, Yasunao*; Sato, Yoichi*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.19 - 23, 2023/01

https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TUOB/TUOB01.pdf

In the J-PARC main ring, density modulation due to longitudinal beam instability occurs during the debunching process of coasting beams. This leads to the generation of an electron cloud, which in turn causes transverse beam instabilities. The transverse beam instability causes beam loss and the electron cloud is assumed to cause vacuum degradation, both of which hinder the beam intensity enhancement, so it is essential to clarify the causes and countermeasures. In particular, the longitudinal impedance of several hundred MHz has been investigated as relevant, and measures to reduce the impedance of individual devices are underway. The Eddy-current type septum magnet, newly installed this year, was found to have a large impedance by simulation. Therefore, we are investigating a method to reduce the impedance by a flange loaded with SiC radio wave absorber, which can be applied to locations where there is no spatial margin to install a taper. In this report, we will discuss the characterization of SiC to be used in actual devices, impedance simulation reflecting the results of SiC evaluation, and evaluation of the effect of impedance countermeasures by impedance measurement using the wire method, and progress in evaluating the effect on the beam by beam simulation and beam study.

Tumor radioresistance caused by radiation-induced changes of stem-like cell content and sub-lethal damage repair capability

Fukui, Roman*; Saga, Ryo*; Matsuya, Yusuke; Tomita, Kazuo*; Kuwahara, Yoshikazu*; Ouchi, Kentaro*; Sato, Tomoaki*; Okumura, Kazuhiko*; Date, Hiroyuki*; Fukumoto, Manabu*; et al.

Scientific Reports (Internet), 12(1), p.1056_1 - 1056_12, 2022/01

https://doi.org/10.1038/s41598-022-05172-4

Alive cancer cells after fractionated irradiations with 2 Gy X-rays per day for more than 30 days show clinically relevant radioresistant. Such radioresistance is experimentally interpreted to attributed to the increment of stem-like cell content. However, only an experimental approach cannot clarify the cell responses (DNA damage and cell death induction) of cancer stem cells, so the radioresistant mechanisms remain uncertain. In addition to the conventional cell experiments using radio-resistant cell lines established after fractionated irradiations, in this study we developed a mathematical model (so called integrated microdosimetric-kinetic (IMK) model) explicitly considering cancer stem-like cell content and DNA damage responses and investigated radioresistant mechanisms acquired after fractionated irradiations. The IMK model analysis suggested that the changes of stem-like cell fraction and DNA repair efficiency play important roles of radioresisitance acquired after irradiations. Considering these into the IMK model, we successfully reproduced the experimental survival of various cell lines and various irradiation conditions. This work would contribute to not only the precise understanding of the radioresistant mechanisms induced after irradiation but also predicting curative effects with high precision.

Electronic structure of Li@C; Photoelectron spectroscopy of the Li@C[PF] salt and STM of the single Li@C molecules on Cu(111)

Yamada, Yoichi*; Kuklin, A. V.*; Sato, Sho*; Esaka, Fumitaka; Sumi, Naoya*; Zhang, C.*; Sasaki, Masahiro*; Kwon, E.*; Kasama, Yasuhiko*; Avramov, P. V.*; et al.

Carbon, 133, p.23 - 30, 2018/07

https://doi.org/10.1016/j.carbon.2018.02.106

We report first STM observation of the Li ion endohedral C, which is of a new class of endohedral fullerenes, prepared by means of evaporation of high-purity Li@C[PF] salt in ultra-high vacuum. Prior to the STM measurements, the electronic structure of Li@C in the Li@C[PF] salt was also precisely determined. In the salt, it is shown that Li and PF have nearly single positive and negative charge, respectively, and the C cage is nearly neutral, suggesting that Li@C in the salt retains its original electronic state.

Measurement of neutron production double-differential cross-sections on carbon bombarded with 430 MeV/nucleon carbon ions

Itashiki, Yutaro*; Imabayashi, Yoichi*; Shigyo, Nobuhiro*; Uozumi, Yusuke*; Satoh, Daiki; Kajimoto, Tsuyoshi*; Sanami, Toshiya*; Koba, Yusuke*; Matsufuji, Naruhiro*

Journal of Radiation Protection and Research, 41(4), p.344 - 349, 2016/12

https://doi.org/10.14407/jrpr.2016.41.4.344

Carbon ion therapy has achieved satisfactory results because of high curability and minimally invasiveness. However, patients have a risk to get a secondary cancer. In order to estimate the risk, it is essential to understand particle transportation and nuclear reactions in the patient's body. The particle transport Monte Carlo simulation code is a useful tool to understand them. Since the code validation for heavy ion incident reactions is not enough, the experimental data of the elementary reaction processes is needed. We measured neutron production double-differential cross-sections (DDXs) on a carbon bombarded with 430 MeV/nucleon carbon beam which is a possible candidate of future therapy beam. The experiment was performed at PH2 beam line of the HIMAC of National Institute of Radiological Sciences. The 430 MeV/nucleon carbon beam was irradiated on a 5 cm 5 cm 1 cm graphite target rotated 45 to the beam axis. The beam intensity was set to 10 particles / spill. A 0.5 mm thick NE102A plastic scintillator was placed to monitor the beam intensity. Neutrons produced in the target were measured with two sizes of NE213 liquid organic scintillators located at six angles of 15, 30, 45, 60, 75, and 90. The 5.08 cm long one was used to obtain the neutron spectra from 1 MeV to 10 MeV and the 12.7 cm long one was used above 5 MeV. The 2 mm thick NE102A plastic scintillators to discriminate charged particles were set in front of the neutron detectors. The kinetic energies of neutrons were determined by the time-of-flight (TOF) method. Background neutrons were estimated by a measurement with iron shadow bars between the target and each neutron detector. An electronic circuit for data acquisition consisted of NIM and CAMAC modules. The experimental data was compared with calculated results obtained by Monte Carlo simulation codes as PHITS. The PHITS code reproduced the experimental data well.

Conceptual design of main magnets for the J-PARC RCS energy upgrade

Tani, Norio; Watanabe, Yasuhiro; Hotchi, Hideaki; Harada, Hiroyuki; Yamamoto, Masanobu; Kinsho, Michikazu; Igarashi, Susumu*; Sato, Yoichi*; Shirakata, Masashi*; Koseki, Tadashi*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.708 - 711, 2016/11

http://www.pasj.jp/web_publish/pasj2016/proceedings/PDF/MOP1/MOP113.pdf

At the J-PARC Main Ring (MR), there have been various investigation carried out at the moment aiming at the beam operation of MW order. As one of the investigations, a study of the Rapid-Cycling Synchrotron (RCS) magnets was implemented. Increase of the extraction energy of RCS was needed to reduce beam loss, as beam loss in the MR injection region was large under influence of Space Charge effect at the injection beam of 3GeV. Therefore conceptual design of the extraction energy upgrade using dipole and quadrupole magnets of RCS was performed. In this paper, we will report the contents of the study in extraction energy upgrade of RCS magnets and problems which became clear as a result.

Design study for impermeable function of trench disposal facility for very low level waste generated from research, industrial and medical facilities (Joint research)

Sakai, Akihiro; Kurosawa, Ryohei*; Nakata, Hisakazu; Okada, Shota; Izumo, Sari; Sato, Makoto*; Kitamura, Yoichi*; Honda, Yasutake*; Takaoka, Katsuki*; Amazawa, Hiroya

JAEA-Technology 2016-019, 134 Pages, 2016/10

JAEA-Technology-2016-019.pdf:8.25MB

Japan Atomic Energy Agency has been developing to design trench disposal facility with impermeable layers in order to dispose of miscellaneous waste. Geomembrane liners have a function that prevent seepage of leachant and collect the leachant. However, the geomembrane liners do not necessarily provide the expected performance due to damage generated when heavy equipment contacts with the liner. Therefore, we studied the impermeable layers having high performance of preventing seepage of leachant including radioactivity taking into account characteristics of low permeable materials and effect of multiple layer structure. As results, we have evaluated that the composite layers composed by a drainage layer, geomembrane liners and a low permeable layer are most effective structure to prevent seepage of leachant. Taking into account disposal of waste including cesium, we also considered zeolite containing sheets for adsorption of cesium were installed in the impermeable layers.

Design of injection and extraction at an 8-GeV booster ring and the J-PARC Main Ring for Multi-MW output beam power

Harada, Hiroyuki; Hotchi, Hideaki; Igarashi, Susumu*; Sato, Yoichi*; Koseki, Tadashi

JPS Conference Proceedings (Internet), 8, p.012012_1 - 012012_6, 2015/09

https://doi.org/10.7566/JPSCP.8.012012

The 240-kW output beam power in the J-PARC 50-GeV Main Ring (MR) has been achieved for the 30-GeV user operation with the cycle time of 2.48 sec and the injected beam intensity with the output beam power of 380-kW equivalent from 3-GeV Rapid Cycling Synchrotron (RCS). The target of output beam power in MR is 750-kW by faster cycling and the injected beam intensity of 600-kW equivalent beam from the RCS. The MR are developing the new type power supplies of the MR main magnets and the high-impedance core of the MR RF cavities. The RCS will aim the designed output beam power of 1-MW from the beam commissioning on October 2014 after the peak current upgrade of Linac from 30 to 50-mA. For higher beam power of MR, we have explored the accelerator options. As one of options, 8-GeV Booster Ring (BR) is also designed for increasing the injection energy of the MR. The increasement of injection energy leads to the reducing a space charge force and the increasing the acceptance clearance from the physical aperture of the MR. In this paper, the realistic injection and extraction system of the BR and the new injection system of the MR for Multi-MW output beam power are also described.

Introducing an 8-GeV booster synchrotron between RCS and MR at J-PARC; One possible option toward a multi-MW output beam power from MR

Hotchi, Hideaki; Harada, Hiroyuki; Yamamoto, Masanobu; Igarashi, Susumu*; Koseki, Tadashi*; Sato, Yoichi*

JPS Conference Proceedings (Internet), 8, p.012008_1 - 012008_6, 2015/09

https://doi.org/10.7566/JPSCP.8.012008

Now the J-PARC accelerators (Linac, 3GeV RCS, 50GeV MR) are in transition from the initial beam commissioning phase to the final stage aiming for the design output beam power of 1 MW from RCS and 0.75 MW from MR; RCS is to start 1-MW beam tuning from October 2014 after completing the linac upgrade, and MR aims at 0.75 MW within the next 3 years by introducing new main magnet power supplies with the faster cycling time. In view of such current situation, we have started discussions for the future J-PARC accelerator concept toward a Multi-MW output beam power. In this paper, we discuss the feasibility for the introduction of a new 8-GeV booster synchrotron between RCS and MR as one possible option toward a Multi-MW output beam power from MR, in combination with the RCS beam power upgrade from 1 MW to 2 MW.

Measurement of neutron production cross sections from heavy ion induced reaction

Shigyo, Nobuhiro*; Uozumi, Yusuke*; Imabayashi, Yoichi*; Itashiki, Yutaro*; Satoh, Daiki; Kajimoto, Tsuyoshi*; Sanami, Toshiya*; Koba, Yusuke*; Takada, Masashi*; Matsufuji, Naruhiro*; et al.

JAEA-Conf 2014-002, p.81 - 87, 2015/02

https://doi.org/10.11484/jaea-conf-2014-002

Cancer therapy using heavy ion beam has been adopted as highly advanced medical treatment by reason of its clinical advantages. It has become more important to estimate the risk of secondary cancer from recent survey. During treatment, secondary particles such as neutrons and -rays are producedby heavy ion induced nuclear reactions in a patient body as well as beam delivery apparatuses. For the risk assessment of secondary cancer, it is essential to know contribution of secondary neutrons by extra dose to organs in the vicinity of the irradiated tumor because the secondary neutron has a long flight path length and gives undesired dose to normal tissues in a wide volume. The experimental data of neutron energy spectra are required for dose estimations with high accuracy. Especially, precise data around neutron energy of 1 MeV is required because neutron of the energy region has a large relative biological eectiveness. Estimation of the secondary neutron yield data is important for estimation of radiation safety on both of workers and public in treatment facilities.

Optics tuning at the J-PARC 3-50BT line

Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.39 - 43, 2014/06

http://www.pasj.jp/web_publish/pasj10/proceedings/PDF/SAOS/SAOS01.pdf

http://www.pasj.jp/web_publish/pasj10/proceedings/PDF/SAOS/SAOS01_oral.pdf

The J-PARC 3-50 BT line is the beam transport line of extracted beam from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, which designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, physical aperture of MR with 81 mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50 BT line has the collimators in order to scrape the tail/halo of extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameter in the collimator area for taking full advantage of beam collimation. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.