Ultra slow muon microscopy by laser resonant ionization at J-PARC, MUSE

Yasuhiro Miyake ,K Nishiyama,N Kawamura,M Iwasaki,R Kadono,N Saito,P Strasser,K Shimomura,E Torikai,A Koda,Takashi Nakamura ,Kotaro Okamura ,Shunsuke Makimura ,Satoshi Wada ,Hiroshi Fujimori ,Koji Yokoyama ,Takashi U Ito ,Jumpei Nakamura ,Yutaka Ikedo ,Wataru Higemoto

doi:10.1007/s10751-012-0759-4

Abstract

As one of the principal muon beam line at the J-PARC muon facility (MUSE), we are now constructing a Muon beam line (U-Line), which consists of a large acceptance solenoid made of mineral insulation cables (MIC), a superconducting curved transport solenoid and superconducting axial focusing magnets. There, we can extract 2 × 108/s surface muons towards a hot tungsten target. At the U-Line, we are now establishing a new type of muon microscopy; a new technique with use of the intense ultra-slow muon source generated by resonant ionization of thermal Muonium (designated as Mu; consisting of a μ + and an e − ) atoms generated from the surface of the tungsten target. In this contribution, the latest status of the Ultra Slow Muon Microscopy project, fully funded, is reported.

Highlights

The surface muon beam (μ+, 30 MeV/c) which has been used for the studies of condensed matter physics or chemistry is conventionally obtained from the decay of positive pions (π+) 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
In order to obtain a sufficient yield for the variety of surface, and nano-science, it was essential to embark on a new project at J-PARC MUSE (Muon Science Establishment), where the world strongest pulse muon source is available
At J-PARC MUSE, we are installing the U-Line which consists of a large acceptance solenoid made of mineral insulation cables (MIC) and a superconducting curved transport solenoid and 6 sets of superconducting axial focusing magnets

Summary

Introduction

The surface muon beam (μ+, 30 MeV/c) which has been used for the studies of condensed matter physics or chemistry is conventionally obtained from the decay of positive pions (π+) 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 has been used as a probe for bulk phenomena rather than surface phenomena In these two decades, a new method to generate ultra-slow muon beam with energy 0.2 eV has been developed at KEK and RIKEN-RAL, utilizing the resonant ionization technique [1]. The achieved intensity was equivalent or even larger than that (1.2 × 106/s) at the RIKEN-RAL muon facility [3] This is the reason why the world strongest pulsed muon source was claimed to be achieved at MUSE even by using only a 120 kW proton beam. This intensity would correspond to 1.5 × 107/s surface muons when in the future the proton beam power will reach 1 MW [4]. In addition to D-Line, we were funded to install the second muon beamline, so called U-Line, which consists of a large acceptance solenoid made of mineral

Ultra slow muon microscopy

Summary