BREMSSTRAHLUNG FROM MUONS SCATTERED BY ATOMIC ELECTRONS

Bremsstrahlung from ultrarelativistic muons that is due to their inter action with atoms and which is accompanied by the excitation of atoms and by the knockout of delta electrons is considered. The process is d escribed by diagrams of two types corresponding to photon emission by a muon or by an electron. For diagrams of the first type, the cross se ction is calculated with allowance for the binding of electrons in ato ms, and a simple approximate formula is given. It is shown that the su bstitution Z(2) --> Z(Z + const), which is often used to take into acc ount bremsstrahlung from muons scattered by atomic electrons, is incor rect. The contribution from diagrams of the second type is treated as an addition to elastic mu e scattering, important radiative correction s of order alpha(3) being included simultaneously. The distribution of energy lost by a muon in a collision and a correction to the mean ene rgy loss by ionization are obtained.