o-Ps annihilation parameters in Pt, 5% Pt-on-charcoal, Pd and 5% Pd-on-charcoal powders J.L. CIOTTONE, F. LANDER and D. LECLAIR J. Phys. IV France, 03 C4 (1993) C4-185-C4-191 DOI: 10.1051/jp4:1993425