Ionization loss of muons in a plastic scintillator

A study has been made of the energy loss of cosmic ray muons in an organic scintillation counter over the momentum range 0.4 to 100 GeV/ c . The results were obtained by using a block of plastic phosphor 3.82 g cm -2 thick in the beam of the Durham cosmic ray spectrograph. The results are compatible with the Sternheimer density correction to the ionization loss theory of Bethe-Bloch up to 10-15 GeV/ c , but they suggest that at higher momenta the most probable energy loss may be about 3%±1% above the predicted rise. The energy loss of positive and negative muons is found to be the same within 1%. The work described is based on 5089 particles, 810 having momentum not less than 20 GeV/ c .