IPAC2013 - List of Authors (Naito, F.)

Paper	Title	Page
TUPFI003	The Accelerator Design of Muon g-2 Experiment at J-PARC	1334
	S. Artikova, F. Naito, M. Yoshida KEK, Ibaraki, Japan
	New muon g-2 experiment at J-PARC is aimed to improve the precise measurement of the muon g-2. In this experiment, the ultra-cold muons created in the muonium target region is reaccelerated to around 300MeV/c in momentum (210 MeV kinetic energy) to then be injected into the muon g-2 storage ring to measure the decay products depending on the muon spin. The linac has advantage over circular accelerators to shorten the reacceleration time in the limited life time of muon. The muon linac consists of the initial acceleration (to 0.01 of v/c), bunching section (0.01 to 0.08 of v/c), low beta section (0.08 to 0.3 of v/c), middle beta section (0.3 to 0.7 of v/c) and high beta section (0.7 to 0.94 of v/c). As a part of the design consideration of this linac, we mainly present the simulation result of initial acceleration and further acceleration of muons with RFQ. An electric field is used to extract the ultra-cold muons from the laser ionization region and RF field is used to create some bunches and to accelerate to higher energies.

THPWO034	Fabrication of the RFQ III for the J-PARC Linac Current Upgrade	3839
	T. Morishita, Y. Kondo, H. Oguri JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan K. Hasegawa JAEA, Ibaraki-ken, Japan H. Kawamata, F. Naito, T. Sugimura KEK, Ibaraki, Japan
	The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The J-PARC linac has been operating for users with the beam energy of 181 MeV. The energy (to 400MeV) and current (to 50mA) upgrade of the linac is scheduled for 1MW operation at RCS. For the current upgrade, the RFQ III, which is designed for 50mA beam acceleration, has been fabricated. The engineering design and the fabrication technologies are basically the same as the RFQ II in J-PARC linac. Some engineering methods are improved for the dimension accuracy, the reliability, and the period of fabrication. In the RFQ II fabrication, there was a leakage trouble at the electron-beam-welding spot by the thermal stress at the brazing only occasionally. Then, we changed to all-brazing design. Also, there was a vane deformation after the final machining. This was corrected by changing the method of fixation at the brazing. As a result, a dimension error was in a tolerable range. Currently, the fabrication is in a final process and the high-power test is scheduled at the second quarter of 2012.

THPWO036	Annular-Ring Coupled Structure Linac for the J-PARC Linac Energy Upgrade	3845
	H. Ao, H. Asano, Y. Nemoto, N. Ouchi, J. Tamura JAEA/J-PARC, Tokai-mura, Japan F. Naito, K. Takata KEK, Ibaraki, Japan
	The linac of Japan Proton Accelerator Research Complex (J-PARC) is the injector to the 3-GeV rapid cycle synchrotron. In order to increase the beam power of the synchrotron, the task of the 400-MeV energy upgrade of the linac started from March 2009. Following the 191-MeV Separated-type DTL, the 25 modules of the Annular-ring Coupled Structure (ACS) linac will be added from August 2013. The operating frequency and the accelerating field E0 of the ACS are 972 MHz and 4.2 MV/m, respectively. The cavity fabrication of the ACS has been almost finished, and then the completed cavities are stored in the J-PARC site. Currently, pumps and vacuum components are being installed on the cavities for the test of vacuum condition. For the pulsed beam of J-PARC, the vacuum pressure have to be less than 10^-6 Pa in order not to exceed 0.1 W/m beam loss. In this paper, we present the R&D results to reduce the vacuum pressure using the stored ACS cavity and the current status of the energy upgrade.

Paper

Title

Page

The Accelerator Design of Muon g-2 Experiment at J-PARC

1334

S. Artikova, F. Naito, M. Yoshida
KEK, Ibaraki, Japan

New muon g-2 experiment at J-PARC is aimed to improve the precise measurement of the muon g-2. In this experiment, the ultra-cold muons created in the muonium target region is reaccelerated to around 300MeV/c in momentum (210 MeV kinetic energy) to then be injected into the muon g-2 storage ring to measure the decay products depending on the muon spin. The linac has advantage over circular accelerators to shorten the reacceleration time in the limited life time of muon. The muon linac consists of the initial acceleration (to 0.01 of v/c), bunching section (0.01 to 0.08 of v/c), low beta section (0.08 to 0.3 of v/c), middle beta section (0.3 to 0.7 of v/c) and high beta section (0.7 to 0.94 of v/c). As a part of the design consideration of this linac, we mainly present the simulation result of initial acceleration and further acceleration of muons with RFQ. An electric field is used to extract the ultra-cold muons from the laser ionization region and RF field is used to create some bunches and to accelerate to higher energies.

THPWO034

Fabrication of the RFQ III for the J-PARC Linac Current Upgrade

3839

T. Morishita, Y. Kondo, H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Hasegawa
JAEA, Ibaraki-ken, Japan
H. Kawamata, F. Naito, T. Sugimura
KEK, Ibaraki, Japan

The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The J-PARC linac has been operating for users with the beam energy of 181 MeV. The energy (to 400MeV) and current (to 50mA) upgrade of the linac is scheduled for 1MW operation at RCS. For the current upgrade, the RFQ III, which is designed for 50mA beam acceleration, has been fabricated. The engineering design and the fabrication technologies are basically the same as the RFQ II in J-PARC linac. Some engineering methods are improved for the dimension accuracy, the reliability, and the period of fabrication. In the RFQ II fabrication, there was a leakage trouble at the electron-beam-welding spot by the thermal stress at the brazing only occasionally. Then, we changed to all-brazing design. Also, there was a vane deformation after the final machining. This was corrected by changing the method of fixation at the brazing. As a result, a dimension error was in a tolerable range. Currently, the fabrication is in a final process and the high-power test is scheduled at the second quarter of 2012.

THPWO036

Annular-Ring Coupled Structure Linac for the J-PARC Linac Energy Upgrade

3845

H. Ao, H. Asano, Y. Nemoto, N. Ouchi, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
F. Naito, K. Takata
KEK, Ibaraki, Japan

The linac of Japan Proton Accelerator Research Complex (J-PARC) is the injector to the 3-GeV rapid cycle synchrotron. In order to increase the beam power of the synchrotron, the task of the 400-MeV energy upgrade of the linac started from March 2009. Following the 191-MeV Separated-type DTL, the 25 modules of the Annular-ring Coupled Structure (ACS) linac will be added from August 2013. The operating frequency and the accelerating field E0 of the ACS are 972 MHz and 4.2 MV/m, respectively. The cavity fabrication of the ACS has been almost finished, and then the completed cavities are stored in the J-PARC site. Currently, pumps and vacuum components are being installed on the cavities for the test of vacuum condition. For the pulsed beam of J-PARC, the vacuum pressure have to be less than 10^-6 Pa in order not to exceed 0.1 W/m beam loss. In this paper, we present the R&D results to reduce the vacuum pressure using the stored ACS cavity and the current status of the energy upgrade.