Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
KEK, Ibaraki, Japan
JAEA/J-PARC, Tokai-mura, Japan
KMI, Nagoya, AIchi Prefecture, Japan
Ibaraki University, Ibaraki, Japan
RIKEN Nishina Center, Wako, Japan
JAEA, Ibaraki-ken, Japan
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Kyoto ICR, Uji, Kyoto, Japan
Sokendai, Ibaraki, Japan
University of Tokyo, Tokyo, Japan
Nagoya University, Nagoya, Japan
J-PARC E34 experiment intends to measure the anomalous magnetic moment and electric dipole moment of muon precisely by a different way from the previous experiment. In this experiment, a low-emittance muon beam is provided using the muons with the thermal energy and the four-stage linac. The demonstration of the first muon RF acceleration with an RFQ linac was conducted and the transverse profile of the accelerated muons was measured last year. As one of the remaining issues for the beam-diagnostic system, the longitudinal beam profile after the RFQ should be measured to match the profile to the designed acceptance of the subsequent accelerator. For this purpose, the new longitudinal beam monitor using the micro-channel plate is under development. The time resolution aims to be around 30 to 40 ps corresponding to 1 % of a period of an operation frequency of the accelerator, which is 324 MHz. On November 2018, the bunch structure of accelerated muons of 89 keV with the RFQ was measured using this monitor at the J-PARC MLF. The latest analysis result of this measurement will be reported in this poster.
Ibaraki University, Ibaraki, Japan
JAEA/J-PARC, Tokai-mura, Japan
RLNR, Tokyo, Japan
Kyoto ICR, Uji, Kyoto, Japan
NIRS, Chiba-shi, Japan
KEK, Ibaraki, Japan
University of Tokyo, Tokyo, Japan
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
An inter-digital H-mode drift-tube linac (IH-DTL) is developed in a muon linac at the J-PARC E34 experiment. IH-DTL will accelerate muons from 0.34 MeV to 4.5 MeV at a drive frequency of 324 MHz. Since IH-DTL adopts an APF method, with which the beam is focused in the transverse direction using the RF field only, the proper beam matching of the phase-space distribution is required before the injection into the IH-DTL. Thus, an IH-DTL prototype was fabricated to evaluate the performance of the cavity and beam transmission. As a preparation of the high-power test, a test coupler is designed and fabricated. In this paper, the development of the coupler and the result of the low-power measurement will be presented.
University of Tokyo, Tokyo, Japan
Ibaraki University, Ibaraki, Japan
KEK, Ibaraki, Japan
JAEA/J-PARC, Tokai-mura, Japan
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
Muon linac is developed for the muon g-2/EDM experiment at J-PARC. In this experiment, ultra slow muon is accelerated to a momentum of 300 MeV/c with the four linac structures. This scheme offers new opportunity for precise measurements; it enables us to reverse muon polarization at early stage of acceleration. The reversal of polarization is a common method of precision polarization measurements as it can be used to identify or reduce systematic uncertainties dependent on time. It is necessary to accelerate muons and flip its spin without substantial emittance growth for the experimental requirement. As one of the candidates for our spin rotator, we are developing the Wien-filter type. In this poster, the design of the Wien-filter type spin rotator for the low emittance muon beam will be presented.
KEK, Ibaraki, Japan
JAEA/J-PARC, Tokai-mura, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
Ibaraki University, Ibaraki, Japan
Nagoya University, Nagoya, Japan
RIKEN Nishina Center, Wako, Japan
University of Tokyo, Tokyo, Japan
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Negative muonium ion production is one of methods to cool muons. Since its discovery in 1987 by interactions of muons with a metal foil, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 (12CaO·7AlO3) was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has lower work function (2.9 eV) and it was reported that nearly the same negative current signal as that with a bi-alkali material coated metal were observed in H− formation. In this poster, the negative muonium production measurement with a Al foil and C12A7 electride film will be presented.
Nagoya University, Nagoya, Japan
KEK, Ibaraki, Japan
JAEA/J-PARC, Tokai-mura, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
KMI, Nagoya, AIchi Prefecture, Japan
Ibaraki University, Ibaraki, Japan
JAEA, Ibaraki-ken, Japan
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
University of Tokyo, Tokyo, Japan
The J-PARC E34 experiment aims to measure the muon anomalous magnetic moment and the electric dipole moment with a high precision. In this experiment, ultra-slow muons generated from thermal muonium production and laser resonance ionization are accelerated in a multistage muon linac. In order to satisfy the experimental requirements, a suppression of the emittance growth between different accelerating cavities is necessary, and the transverse and longitudinal beam matching is important. Longitudinal beam monitor has to measure the bunch width with a precision of 1% corresponding to several tens of picoseconds. In addition, the beam monitor should be sensitive to a single muon, because the beam intensity during the commissioning is lower than the designed intensity. Therefore, we are developing a longitudinal beam monitor using a microchannel plate (MCP), and a measurement system using photoelectrons to estimate the performance of the beam monitor. On November 2018, the beam monitor has been successfully used in the muon RF acceleration test at the J-PARC. In this presentation, the results of the performance evaluation for this beam monitor are reported.