Development of a new imaging system by MuSR

The muon spin relaxation/rotation/resonance (MuSR) technique is one of the strongest methods to examine material characters and has been used for many years. We irradiate muon beams into a sample and detect positrons emitted from muon decays, and obtain information about the sample by utilizing the asymmetry of positrons. However, the detector set does not have spatial resolutions at all, so MuSR is not good for the research of samples made from many kinds of materials so far. Therefore, our group is trying to develop a new imaging technique as an extension of MuSR. So, we made a new detector set made of plastic scintillation fibers so that we can track back trajectories of each positron, identify where they come from in the sample, and analyze MuSR data at each position in it to make an image of it.

We conducted experiments at M20C beamline at TRIUMF in Canada. We used muon beams created from pion decays and the polarization of muon beams is 100 %. We have already got the result that gives us the distribution of materials on the sample surface. According to the result, we can see the difference of materials from that of the amplitude and/or the frequency of muon spin rotation spectra.

At the conference, I am going to present the newer experiment and result as well as the detail of this research.