Hiroshi Fujimori

Ultra Slow Muon Project at J-PARC, MUSE

The muon science facility (MUSE), along with the neutron, hadron, and neutrino facilities, is one of the experimental areas of the J‐PARC project, which was approved for construction at the Tokai JAEA site. The MUSE facility is located in the Materials and Life Science Facility (MLF), which is a building integrated to include both neutron and muon science programs. Construction of the MLF building was started in the beginning of 2004, and first muon beam is expected in the autumn of 2008.As a next step, we are planning to install, a Super Omega muon channel with a large acceptance of 400 msr, to extract the world strongest pulsed surface muon beam. Its goal is to extract 4×108 surface muons/s for the generation of the intense ultra slow muons, utilizing laser resonant ionization of Mu by applying an intense pulsed VUV laser system. As maximum 1×106 ultra slow muons/s will be expected, which will allow for the extension of μSR into the field of thin film and surface science.

The Next Generation Muon Source at J‐PARC/MLF

The Materials and Life Science Facility (MLF) is currently under construction at J‐PARC in Tokai, Japan. The muon section of the facility will house the muon production target and four secondary beam lines used to transport the muons into two experimental halls. Currently, one of the four beam lines (the Decay beam line) has been completed and is operational. The beam line currently under construction is the large acceptance beam line (the so called Super‐Omega beam line) which, when completed, will produce the highest intensity pulsed muon beam in the world. The expected rate of surface muons for this beam line is 4×108 μ+/s, and a cloud muon rate of 107 μ−/s. The beam line consists of the normal‐conducting capture solenoids, the superconducting curved transport solenoids, and an axial focusing magnet. The capture solenoids have been fabricated and installed on the beam line, while the transport solenoids are under design, with initial prototype coils under fabrication.

J-PARC decay muon channel construction status

The new Muon Science Facility (MUSE) that is now under construction at J-PARC in the Materials and Life Science Facility (MLF) building will comprise four types of muon channels. In the first stage, a conventional superconducting decay muon channel (D-Line) was constructed, which can extract surface (positive) muons with an expected muon yield of 107/s and decay positive/negative muons up to 120 MeV/c, with an expected muon yield of a few 106/s at 60 MeV/c for both positive and negative muons. This channel will be used for various kinds of muon experiments like ?SR, muon catalyzed fusion and nondestructive elements analysis.

Design of the Large Acceptance Muon Beamline at J-PARC

The Materials and Life Science Facility (MLF) is currently under construction at J‐PARC in Tokai, Japan. The muon section of the facility will house the muon production target and four secondary beamlines used to transport the muons into two experimental halls. One of the beamlines is a large acceptance beamline (the so called Super Omega Muon beamline) which, when completed, will produce the largest intensity pulse muon beam in the world. The expected rate of surface muons for this beamline is 5×108 μ+/s, and a cloud muon rate of 107 μ−/s. The extracted muons will be used for projects involving the production of ultra‐slow muons as well as for muon‐catalyzed fusion. The beamline consists of the normal‐conducting capture solenoids, the superconducting curved transport solenoids, and the Dai Omega‐type axial focusing magnet. Currently, the capture and transport solenoids are under design, with the former in its final stages and the latter being finalized for construction of test coils. The design of the Da...

Construction of Ultra Slow Muon Beam Line at J-PARC

T. Nagatomo1, Y. Ikedo1, P. Strasser1, S. Makimura1, J. Nakamura1, K. Nishiyama1, K. Shimomura1, N. Kawamura1, A. Koda1, H. Fujimori1, Y. Kobayashi1, T.U. Ito2, W. Higemoto2, A.D. Pant3, R. Kadono1, E. Torikai3 and Y. Miyake1 1Muon Science Laboratory, High Energy Accelerator Research Organization (KEK), Ibaraki 319-1106, Japan 2Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Ibaraki 319-1184, Japan 3Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 400-0016, Japan

Development of High-Rate Positron Tracker for the Muonium Production Experiment at J-PARC

1 Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan 2 Institute of Materials Structure Science, KEK, 1-1 Oho, Tsukuba, Ibaraki, Japan 3 Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba, Ibaraki, Japan 4 Advanced Meson Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan 5 Department of Physics, Korea University, 145, Aman-ro, Seongbuk-gu, Seoul, 137-713, Korea 6 Department of Physics, Tokyo University of Science, 1-3, Kagurazaka, Sinjuku-ku, Tokyo, Japan

Optimal crossed overlap of coherent vacuum ultraviolet radiation and thermal muonium emission for μSR with the Ultra Slow Muon

For μSR with ultra slow muon, we are constructing U line in materials and life science facility (MLF), J-PARC at present. Generation of ultra slow muon requires thermal muonium generation and laser resonant ionization process with vacuum ultraviolet radiation (1S→2P) and 355-nm radiation (2P→unbound). For laser resonant ionization, the coherent radiations and the thermal muonium emission must be coincident in time and space. The radiations can be steered in a chamber for reasonable overlap in space, and they can be easily overlapped in time because they are generated from one laser source. The trigger signal of the accelerator is useful for stable overlap in time.

Ultra Slow Muon Microscopy for Nano-science

The surface muon beam which has been used for the studies of condensed matter physics or chemistry is conventionally obtained from the decay of positive pions (?+) stopped near the surface of the pion production target in the proton beam line and has large energy broadening with an implantation depth of 0.1 to 1 mm. Despite the name of surface muon, it is used as a probe of bulk phenomena rather than surface phenomena. In these two decades, the new method to generate ultra-slow muon beam with energy 0.2 eV has been developed and successfully obtained by KEK and RIKEN group. When the production of intense ultra-slow muon source will be realized, the use of its short-range penetration depth will allow muon science to be expanded towards a variety of new nano-scientific fields, which we call Ultra Slow Muon Microscope such as, 1) Surface/boundary magnetism utilizing its spin polarization and unique time-window. 2) Surface chemistry, utilizing a feature of a light isotope of hydrogen; such as catalysis reactions. 3) Muon Microscopy, utilizing a feature of micron meter beam size, when ultra slow muon is accelerated. 4) Precise atomic physics testing QED, since Mu is the simplest lepton pair consisting ?+ and e?. 5) Ion sources for- g-2 experiment, and towards ?+ ?? collider experiments in high-energy physics. Int this paper, the latest status of the intense low-emittance ultra slow muon source and its scientific prospects will be reported.

The status of the Superomega muon beamline

The Superomega muon beamline is currently under construction at Experimental hall No. 2 of the Materials and Life Science Facility at J‐PARC in Tokai, Japan. The beamline has a large solid angle acceptance, and will produce the highest intensity pulsed muon beam in the world. The beamline is designed to capture both surface positive and cloud negative muons for simultaneous use in a variety of experiments. The expected rate of surface muons for this beamline is 4×108 μ+/s, and that for cloud muons is 107μ−/s. The beamline consists of the normal‐conducting capture solenoid, the superconducting curved transport solenoid and axial focusing solenoid. The construction of the capture solenoid has been completed and installed in March 2009, and the transport solenoid is now fabricated, and will be installed in the summer of 2011. The calculation of the beamline optics of the axial focusing solenoid is underway.

Present Status of Muon Production Target at J-PARC/MUSE

Shunsuke MAKIMURA*1, 2, Naritoshi KAWAMURA1, 2, Satoshi ONIZAWA3, Yukihiro MATSUZAWA3, Masato TABE4, Yasuo KOBAYASHI1, 2, Ryo SHIMIZU3, Hiroshi FUJIMORI1, 2, Yutaka IKEDO1, 2, Ryosuke KADONO1, 2, Akihiro KODA1, 2, Kenji M. KOJIMA1, 2, Kusuo NISHIYAMA1, 2, Jumpei NAKAMURA1, 2, Koichiro SHIMOMURA1, 2, Patrick STRASSER1, 2, Masaharu AOKI5, Yohei NAKATSUGAWA2, and Yasuhiro MIYAKE1, 2 . 1Muon Section, Materials and Life Science Division, J-PARC center, Tokai, Ibaraki 319-1195, Japan 2Muon Science Laboratory, High Energy Accelerator Research Organization (KEK-IMSS), Tokai, Ibaraki 319-1195, Japan 3The NIPPON ADVANCED TECHNOLOGY CO., LTD (NAT), Tokai, Ibaraki 319-1112, Japan 4Seekel Co., Ltd., Mito, Ibaraki 310-0851, Japan 5Osaka University, Toyonaka, Osaka 560-0043, Japan