Elastic Scattering of 1.2-BeV/cMuons from Hydrogen

The absolute cross section for the elastic scattering of negative muons from protons was measured over a range of momentum transfers of 450 to 850 MeV/c. The muon beam was formed by decay in flight of Bevatron produced pions and was separated from the pion beam electronically by using four gas-filled threshold \ifmmode \check{C}\else \v{C}\fi{}erenkov counters. A total of 3\ifmmode\times\else\texttimes\fi{}${10}^{8}$ muons were incident on two large liquid hydrogen targets in tandem and gave a total of 56\ifmmode\pm\else\textpm\fi{}9 acceptable scattering events, as compared to 48 predicted by the Rosenbluth formula for electromagnetic scattering from protons. A $\ensuremath{\chi}$-square analysis of the scattered events gave agreement at the 75% level for the angular distribution of the data and the theoretical predictions, and gave with 95% confidence ${\ensuremath{\Lambda}}^{\ensuremath{-}1}\ensuremath{\le}0.16$ F, where ${\ensuremath{\Lambda}}^{\ensuremath{-}1}$ is the conventional breakdown parameter. Hence, in this experiment, the behavior of muons scattered from protons at large momentum transfers is indistinguishable from that of electrons.