Measurement of residual [formula omitted] polarization in a LaF[formula omitted] scintillating material for a new [formula omitted] polarimeter system

Abstract

A new experimental method to measure muon polarization using a scintillating material has been proposed. One of the key issues for this measurement is the choice of scintillation materials which can maintain the μ+ spin polarization for several μ+ lifetimes. Thus far, a CeF3 scintillating crystal has been known to be only a possible candidate and it is highly preferable to find other scintillators whose performance is nearly equivalent to CeF3. The residual μ+ polarization in a 2% cerium-doped LaF3 scintillating crystal was measured at the J-PARC Material and Life Science Facility (MLF) by applying the longitudinal field (LF) to the LaF3 material. The polarization was obtained to be 83 and 87 % with LF=100 and 140 Gauss, respectively, which is high enough to measure the μ+ polarization in various experiments.