Development of a low-momentum “surface” muon beam for LAMPF

A low momentum positive muon beam has been developed at LAMPF, utilizing muons which originate from pion decays at rest near the surface of the pion production target and are transported by the LAMPF stopped muon channel. The muon beam has a total flux of 2.5 × 104μ+ per s per μA of a proton beam (8 × 106μ+ s−1 for the present operating current at LAMPF of 300 μA), an extremely narrow range spread of 50 mg/cm2 in CH2, and a positron contamination (e+/gm+) of 60%.