Transverse momenta of helium fragments in gold fragmentation at 10.6 GeV/nucleon

The transverse momentum (p t ) distributions of helium fragments from gold fragmentation on different nuclei of nuclear emulsion have been measured and a clear increase of average p t with target mass is seen. The p t distributions can be parameterized by a sum of three exponential functions of the form ∼ exp(-p_t^2/B_i) . The differences in p t distributions in interactions on different targets can be explained by different contributions of the three exponential functions. These contributions depend on the projectile breakup in the collision, and for a given degree of the projectile breakup do not depend on the target mass.