• N. Kuroda, Y. Enomoto, H. Imao, C.H. Kim, Y. Matsuda, H.A. Torii, Y. Yamazaki
  The University of Tokyo, Institute of Physics, Tokyo
• H. Higaki
  HU/AdSM, Higashi-Hiroshima
• H. Hori
  MPQ, Garching, Munich
• Y. Kanai, A. Mohri, Y. Nagata
  RIKEN, Wako, Saitama
• K. Kira
  Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima
• K. Michishio
  Tokyo University of Science, Tokyo
• H. Saitoh
  University of Tokyo, Chiba
• M. Shibata
  KEK, Tsukuba

The ASACUSA collaboration at CERN has been developed a unique Mono-energetic Ulta-Slow Antiproton beam Source for High-precision Investigation (MUSASHI) for collision studies between antiproton and atoms at very low energy region, which also used as an intense ultra-low energy antiproton source for the synthesis of antihydrogen atoms in order to test CPT symmetry. MUSASHI consists of a multi-ring electrode trap housed in a bore surrounded by a superconducting solenoid, which works with a sequential combination of the CERN Antiproton Decelerator and the Radio-Frequency Quadrupole Decelerator. GM-type refrigerators were used to cool the solenoid and also the bore at 4K to avoid losses of antiprotons with residual gasses. Up to 1.8 millions of antiprotons per one AD cycle were successfully trapped and cooled. MUSASHI achieved to accumulate more than 12 millions of cold antiprotons by stacking several AD shots. Such cooled antiprotons were extracted as 150 or 250eV beams with various bunch lengths from 2 micoroseconds to 30 seconds long, whose energy width was the order of sub-eV. The beam intensity was enhanced by a radial compression technique for the trapped antiproton cloud.