Abstract

Double differential cross sections d(2) sigma/dpd Omega have been measured for pi(+) and K+ emitted around midrapidity in d + A and alpha + A collisions at a beam kinetic energy of 1.15 GeV/nucleon. The total pi(+) yield increases by a factor of about 2 when using an alpha projectile instead of a deuteron whereas the K+ yield increases by a factor of about 4. According to transport calculations, the K+ enhancement depends both on the number of hadron-hadron collisions and on the energy available in those collisions: their center-of-mass energy increases with increasing number of projectile nucleons. (C) 1997 Published by Elsevier Science B.V.