Basic Science Research by High Intensity Meson Beams

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Experiments on laser resonance spectroscopy on metastable antiprotonic atoms were carried out at CERN. When a pulsed laser with an energy matched to a transition from a metastable state to a short lived state is fired after the arrival of an antiproton, a sharp spike is expected to appear on a delayed part of the antiproton annihilation time spectrum. We used the antiproton beam of 200MeV/c from the Low Energy Antiproton Ring (LEAR) of CERN.We discovered a sharp spike at a laser wave length of 597.26nm which was assigned to a resonance transition from the (n, iota) =(39, 35) to the (38, 34) state. Thus, we have established that the metastability of antiprotons in helium arises from the metastable states of the neutral antiprotonic helium atomcule.Regarding the search for deeply-bound pionic atoms we prepared an experiment to be done at GSI in collaboration with a group in Germany.Various experiments were carried out at the TRIUMF muon facilities. One of the purposes of this project is … More to obtain the basic understanding of high Tc superconductors, especially the role of the copper-oxide layer structure and the contribution of oxygen to the superconductivity. Since the intense negative muon channel at TRIUMF was built by the collaboration between UTMSL and TRIUMF, the negative muon spin rotation method (mu^-SR) has been intensively applied to this subject.By using a single crystal of good quality, precise paramagnetic shift was obtained on the LaSrCuO system with its dependence on temperature, on dopant concentration and on magnetic field direction with respect to the crystal axis. The relaxation of negative muonic oxygen (mu^-O) has also been studied to get the dynamic aspect of the electron spin.One remarkable achievement is the success of the separation of mu^-O signals for different oxygen sites, which gives the hints for the role of oxygen.Also for water knowledge of chemical state of mu^-O can be obtained. For the basic understanding of mu^-O in metal oxides, the study of mu^-O in 3d transition metal oxides is inevitable. The study is performed on various 3d-transition metal oxides, especially the precise measurement of temperature dependence of paramagnetic shift in MnO reveals an interesting local magnetic ordering.Some of these achievements were reported at the muSR international conference in Maui. Less