KEK-MSL report 2004

This is an annual report of KEK-MSL in 2004. The subjects of facility developments and the condensed matter studies at the home laboratory as well as overseas laboratories of TRIUMF and RIKEN/RAL have been markedly progressed. The completed large solid-angle superconducting channel (Dai-Omega) at No.2 laboratory was used primarily for the thermal muonium production experiment. The construction of Japan Proton Accelerator Research Complex (J-PARC) is proceeding smoothly, and the Material and Life Sciences Facility (MLF) building that accommodate the new Muon Science Laboratory at J-PARC is taking the actual shape with numerous beams. As it can be seen in this report, a number of detailed design works have been made in various components of the MSL/J-PARC. On the 1st of April 2004, High Energy Accelerator Research Organization (KEK) was incorporated into an Inter-University Research Institute Corporation. At the same time, the Meson Science Laboratory was renamed as Muon Science Laboratory. This report includes 4 facility reports, various scientific activities as well as KEK-MSL TRIUMF/RIKEN-RAL collaborations. (J.P.N.)