LIFETIMES OF CHARMED PARTICLES PRODUCED IN A 20-GEV GAMMA-P EXPERIMENT - ABE,K; BACON,TC; BALLAM,J; BERNY,L; BEVAN,AV; BINGHAM,HH; BRAU,JE; BRICK,D; BUGG,WM; BUTLER,J; CAMERON,W; CARROLL,JT; et al. (PHYSICAL REVIEW LETTERS, 1982)