"cloud" and "surface" Muon Beam Characteristics

Muon rates and polarizations have been measured on several beam channels at LAMPF to characterize muon production from the primary target surface or adjacent volume. To produce these "surface" or "cloud" beams, the channel is tuned to accept beam directly from the target. The measurements range from 20-200 MeV/c in muon momentum at production angles of 20, 45, and 65°. Both μ+ and μ- rates, and μ+ polarization were measured. Surface beam polarization is close to 100%, while cloud beam polarization is low. The surface μ+ rate dependence upon proton beam depth in the target was studied.