KEK, Ibaraki, Japan
SNU, Seoul, Republic of Korea
JAEA/J-PARC, Tokai-mura, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
Ibaraki University, Ibaraki, Japan
RIKEN Nishina Center, Wako, Japan
University of Tokyo, Tokyo, Japan
The University of Tokyo, Graduate School of Science, Tokyo, Japan
Budker INP & NSU, Novosibirsk, Russia
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Korea University, Seoul, Republic of Korea
The E34 experiment aims to measure muon anomalous magnetic moment with a precision of 0.1ppm. The experiment utilizes low emittance muon beam with a muon linac to sweep out beam related uncertainties, which limit the g-2 precision in past experiments. A beam matching with precise beam measurements is required to avoid substantial emittance growth and satisfy the experimental requirement on the beam emittance of around 1.5 pi mm mrad. We conduct profile measurement of muon after acceleration with a radio-frequency quadrupole (RFQ) on December 2017 following a first muon acceleration experiment on October. In the experiment of profile measurement, epi-thermal negative muonium ions are generated by injecting surface muons to a thin metal foil. The muonium ions are accelerated to 5 keV. by an electro-static lens and accelerated to 90 keV by the RFQ. Then the muonium ions are transported to a profile detector consisting of a micro-channel plate and a ccd camera via a quadrupole pair and a bending magnet. In this poster, the experimental result and comparison to the simulation are reported.
University of Tokyo, Tokyo, Japan
SNU, Seoul, Republic of Korea
KEK, Ibaraki, Japan
JAEA/J-PARC, Tokai-mura, Japan
Ibaraki University, Ibaraki, Japan
Budker INP & NSU, Novosibirsk, Russia
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
J-PARC E34 experiment aims to measure the muon g-2/EDM precisely with novel techniques including the muon linear accelerator. Slow muon source by the metal foil method in order to cool the muon beam has been developed for the muon acceleration test with RF accelerator, because the muon beam derived from the proton driver was the tertiary beam and has a large emittance. The first verification test of the muon acceleration with RFQ was carried out at the muon test beam line of J-PARC MLF in October 2017. The incident surface muons were decelerated by the thin metal foil target and produced the negative muonium ions (Mu-), which is the bound stat of a positive muon and two electrons. After Mu- were extracted by a electrostatic accelerator as the injector of the RFQ, they were accelerated with RFQ to 88.6 keV. The accelerated Mu- were identified by the momentum selection with the bending magnet after the RFQ, and the measurement of the Time-Of-Flight. Accelerated Mu- were easily distinguished from penetrated positive muons by the difference of the polarity. The latest analysis result of the world's first muon acceleration with RFQ will be reported in this paper.
Ibaraki University, Hitachi, Ibaraki, Japan
Sokendai, Ibaraki, Japan
KEK, Ibaraki, Japan
A newly developed three-dimensional spiral injection scheme for beam insertion into a compact (medical MRI size) solenoidal storage ring is introduced. This is a one of key R&D items for a new planned muon g-2/EDM experiment at J-PARC, which aims to measure g-2 to a factor 5 better statistical precision and a factor of 100 better sensitivity for the electric dipole moment measurement (EDM) compared to the previous experiments. The new scheme provides a smooth injection utilizing a radial solenoidal fringe field, without causing any error field in the storage volume. Magnetic pulsed kicker will guide and set the beam in the storage field volume. The strongest point of this new scheme is that any source of the electric field is removed in this scheme to perform ideal EDM measurement. We have performed a test bench experimental work to demonstrate a feasibility of this new injection scheme. Instead of the muon beam, we inject electron beam, from an electron-gun, into the solenoid magnet, and detect three-dimensional spiral beam trajectory inside of the storage chamber by CCD camera. We will discuss outline of a new injection scheme and the latest results from the test bench works.
*H. Iinuma et al.,Nuclear Instruments and Methods in Physics Research A, 832, 51-62 (2016)
JAEA/J-PARC, Tokai-mura, Japan
SNU, Seoul, Republic of Korea
KEK, Ibaraki, Japan
RLNR, Tokyo, Japan
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
Ibaraki University, Ibaraki, Japan
RIKEN Nishina Center, Wako, Japan
Kyoto ICR, Uji, Kyoto, Japan
NIRS, Chiba-shi, Japan
University of Tokyo, Tokyo, Japan
The University of Tokyo, Graduate School of Science, Tokyo, Japan
Budker INP & NSU, Novosibirsk, Russia
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
J-PARC is developing the reacceleration system of the ultra slow (30 meV) muon (USM) obtained by two-photon laser resonant ionization of muonium atoms. The muon beam thus obtained has low emittance, meeting the requirement for the g-2/EDM experiment. J-PARC E34 experiment aims to measure the muon anomalous magnetic moment (g-2) with a precision of 0.1 ppm and search for EDM with a sensitivity to 10-21 e cm. The USM's are accelerated to 212 MeV by using a muon dedicated linac to be a ultra cold muon beam. The muon LINAC consists of an RFQ, a inter-digital H-mode DTL, disk and washer coupled cell structures, and disk loaded structures. The ultra-cold muons will have an extremely small transverse momentum spread of 0.1% with a normalized transverse emittance of around 1.5 pi mm-mrad. Proof of the slow muon acceleration scheme is an essential step to realize the world first muon linac. In October 2017, we have succeeded to accelerate slow negative muoniums generated using a simpler muonium source to 89 keV. In this talk, present design of the muon linac and the result of the world first muon acceleration experiment are reported.
