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Journal Articles

Development of superconducting spoke cavities for laser Compton scattered X-ray sources

Hajima, Ryoichi; Sawamura, Masaru; Kubo, Takayuki*; Saeki, Takayuki*; Cenni, E.*; Iwashita, Yoshihisa*; Tongu, Hiromu*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2902 - 2904, 2015/06

A 5-year research program on the development of superconducting spoke cavities for electron accelerators has been funded by MEXT, Japan since 2013. The purpose of our program is establishing design and fabrication processes of superconducting spoke cavity optimized for compact X-ray sources based on laser Compton scattering. The spoke cavity is expected to realize a compact industrial-use X-ray source with a reasonable cost and easy operation. We have chosen a cavity frequency at 325 MHz due to possible operation at 4 K and carried out cavity shape optimization in terms of electromagnetic and mechanical properties. Production of press-forming dies is also in progress. In this paper, we present overview and up-to-date status of the research program.

Journal Articles

Formation of a uniform ion beam based on nonlinear focusing and its applications at the JAEA TIARA cyclotron

Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Yoshida, Kenichi; Ishibori, Ikuo; Okumura, Susumu

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.236 - 238, 2015/06

Journal Articles

Preliminary studies of laser-assisted H$$^{-}$$ stripping at 400 MeV

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Maruta, Tomofumi*; Okabe, Kota; Yoshimoto, Masahiro; Irie, Yoshiro*; Gorlov, T.*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.3795 - 3797, 2015/06

Journal Articles

Simulation study of muon acceleration using RFQ for a new muon g-2 experiment at J-PARC

Kondo, Yasuhiro; Hasegawa, Kazuo; Otani, Masashi*; Mibe, Tsutomu*; Saito, Naohito; Kitamura, Ryo*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.3801 - 3803, 2015/06

A new muon g-2 experiment is planned at J-PARC. In this experiment, ultra cold muons will be generated and accelerated using a linear accelerator. As the first accelerating structure, an RFQ will be used. We are planning to use a spare RFQ of the J-PARC linac for the first acceleration test. In this paper, simulation studies of this muon acceleration test are presented. A design study of a muon dedicated RFQ is also shown.

Journal Articles

Development of muon linac for the muon g-2/EDM experiment at J-PARC

Otani, Masashi*; Mibe, Tsutomu*; Fukao, Yoshinori*; Saito, Naohito; Yoshida, Mitsuhiro*; Kitamura, Ryo*; Kondo, Yasuhiro; Iwashita, Yoshihisa*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2541 - 2544, 2015/06

Muon acceleration is beyond our experiences. It enables us to measure the muon anomalous magnetic moment with an accuracy of 0.1 ppm and search for electric dipole moment with a sensitivity of 10$$^{-21}$$ e$$cdot$$cm to explore beyond Standard Model of elementary particle physics. We are developing a linac dedicated to the muon acceleration and planning to try the muon acceleration by utilizing slow negative muonium production. This paper described status of these developments.

Journal Articles

Recent progress of J-PARC RCS beam commissioning; Toward realizing the 1-MW output beam power

Hotchi, Hideaki

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1346 - 1348, 2015/06

J-PARC RCS started 1-MW beam tuning from October 2014, and successfully achieved 1-MW beam acceleration in January 2015, where major part of beam loss, such as space-charge induced beam loss, was well minimized by the combination of transverse and longitudinal painting. In addition, very recently, the transverse painting area was successfully expanded by correcting beta function beating during injection caused by the edge focus of the injection bump magnets, by which the foil scattering part of beam loss was further reduced. By these efforts, now the beam loss is at the permissible level for the 1-MW routine beam operation. The main topic of this talk is to discuss our approaches to beam loss issues that we faced on the process of the beam power ramp-up.

Journal Articles

Degassing of kicker magnet by in-situ bake-out method

Kamiya, Junichiro; Ogiwara, Norio; Hikichi, Yusuke; Kinsho, Michikazu; Miki, Nobuharu*; Yanagibashi, Toru*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2911 - 2913, 2015/06

New method of in-situ degassing of the kicker magnet in the beam line has been developed. The heater and heat shielding panels are installed in the vacuum chamber in this method. The heater was designed considering the maintainability. The graphite was selected as the heater and the high melting point metals were used as the reflectors just near the heater. The thermal analysis and the temperature measurement with the designed heater was performed. The ideal temperature distribution for the kicker degassing was obtained. The outgassing of the graphite during rising the temperature was measured. The result showed that the outgassing was extremely suppressed by the first heating. This means the outgassing of the graphite heater was negligible as long as it is used in the beam line without exposure to the air.

Journal Articles

Measurement results of the impedance of the RF-cavity at the RCS in J-PARC

Shobuda, Yoshihiro; Harada, Hiroyuki; Hotchi, Hideaki

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.255 - 257, 2015/06

The kicker impedance dominates at the RCS in J-PARC. Recently, we observe beam instabilities, which are not explained by the kicker. As a candidate causing the beam instability, the impedance of the RF-cavity is measured. The longitudinal impedance is measured by stretching a single-wire inside the cavity. On the other hand, the measurement of the transverse impedance is done by horizontally shifting the single-wire, due to the accuracy problem. The measured impedance is too low to explain the beam instability.

Journal Articles

New injection bump power supply of the J-PARC RCS

Takayanagi, Tomohiro; Hayashi, Naoki; Ueno, Tomoaki*; Horino, Koki; Okabe, Kota; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2908 - 2910, 2015/06

The new injection bump power supply for the shift bump (SB) magnet of the beam injection system at the J-PARC (Japan Proton Accelerator Research Complex) 3-GeV RCS (Rapid-Cycling Synchrotron) has been developed and manufactured. The power capacity of the new power supply demand doubling with the injection beam energy upgrading of the LIANC (Linear Accelerator) from 181 MeV to 400 MeV. Furthermore, the low ripple noise on the output current was required to prevent the occurrence of the resonation between the excitation magnetic field and the RF shield loop covered the ceramics duct at the magnet. The power supply newly adopted a capacitor commutation method to form the trapezoid waveform pattern (bump waveform). This paper reports characteristic about the new shift bump power supply.

Journal Articles

Measurement of Momentum Spread of the Injection Beam with Longitudinal Tomography Method in the J-PARC RCS

Yoshimoto, Masahiro; Harada, Hiroyuki; Hotchi, Hideaki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Kinsho, Michikazu

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.944 - 946, 2015/06

In the J-PARC RCS, the beam tuning toward the design output beam power of 1MW were started after the completing of the beam energy and beam current upgrades in the LINAC. One of the important issues to achieve the 1MW beam operation is the optimization of the injection beam from the LINAC. Due to the longitudinal beam tuning in the LINAC, the momentum spread of the injected beam into the RCS was measured with the longitudinal tomography method. Our longitudinal tomography tool had been developed using the simple algorithm with the Convolution Back Projection (CBP) method for the beam storage mode of the RCS. Accordingly, we improved this tool to expand into the acceleration mode. By tuning the tank level of the debuncher 2 in the LINAC, it can be measured the momentum spread was shifted from 0.06% to 0.15%. Moreover, these distributions of the momentum spread are consistent with the simulation results.

Journal Articles

Status of the J-PARC 3GeV RCS

Kinsho, Michikazu

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.3798 - 3800, 2015/06

Beam power of routine operation of the J-PARC rapid cycling synchrotron (RCS) increased gradually for the MLF user operation, beam power of 400 kW was achieved on 10th March, and 500 kW user operation has been stably performed from 14th April this year. Beam studies were also performed to demonstrate the capability of the RCS to operate at powers in excess of 1 MW. The study produced a beam intensity of 8.41$$times$$10$$^{13}$$ protons during short time, an intensity equivalent to 1.01 MW operation on 10th January 2015. In this beam study it was cleared issues to realize 1MW operation in the RCS. Status of user operation and issues to realize high power operation in the RCS are presented.

Journal Articles

Demonstration of high-flux photon generation from an ERL-based laser Compton photon source

Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Araki, Sakae*; Honda, Yosuke*; Kosuge, Atsushi*; Terunuma, Nobuhiro*; Urakawa, Junji*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1607 - 1609, 2015/06

Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 deg., respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm$$^{2}$$ placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200 /s, 6.91 keV, and 81 eV, respectively.

Journal Articles

Space charge simulation and matching at low energy section of J-PARC LINAC

Artikova, S.; Kondo, Yasuhiro; Morishita, Takatoshi

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.251 - 254, 2015/06

Journal Articles

Multipactor simulations in 325 MHz superconducting spoke cavity for an electron accelerator

Kubo, Takayuki*; Saeki, Takayuki*; Cenni, E.*; Iwashita, Yoshihisa*; Tongu, Hiromu*; Hajima, Ryoichi; Sawamura, Masaru

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2892 - 2894, 2015/06

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