A dependence of muon pair production in π-nucleus interactions at 280 GeV/c

We have measured the relative cross sections for muon pair production by 280 GeV/c negative pions on three different targets: carbon, copper, and tungsten. The value of α obtained from the parametrization sigma = constant X Asup(α) is 0.94 +- 0.02 +- 0.02, whereas the parametrization sigma approx. equal to sigma0(Z/A) Asup(α'), where sigma0(Z/A) is given by the Drell-Yan model, leads to α' = 0.97 +- 0.02 +- 0.02. This last result is in agreement with the quark additivity rule which is inherent in the Drell-Yan model, no dependence is observed on the transverse momentum of the muon pair. (orig.)