ELECTRON LOSS IN COLLISIONS OF IONS WITH NOBLE GASES W.S. Melo, A.C.F. Santos, M.M. Sant'Anna, G.M. Sigaud and E.C. Montenegro Departamento de F=EDsica, Pontif=EDcia Universidade Cat=F3lica do Rio de Janeiro, PUC-Rio, Cx. Postal 38071, Rio de Janeiro, RJ 22452-970, Brazil We have measured total electron loss cross sections of 1.0-to-4.0-MeV He(+), C(3+) and O(5+) ions by noble gases as well as electron loss accompanied by target ionization for He(+) in these gases. The results are compared with calculations for the screening contribution to the electron loss, based on the coupled-channel method and the sudden approximation for the He(+), and on the free-collision model for He(+),C(3+) and O(5+).