Nuclear Dependence of Charm Production

With data taken by SELEX, which accumulated data during the 1996-1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with {Sigma}{sup -}, p, {pi}{sup -}, and {pi}{sup +} beams. Parameterizing the production cross section {infinity} A{sup {alpha}}, A being the atomic number, we determine {alpha} for D{sup +}, D{sup 0}, D{sub s}{sup +}, D{sup +}(2010), {Lambda}{sub c}{sup +}, and their respective anti-particles, as a function of their transverse momentum p{sub t} and scaled longitudinal momentum x{sub F}. Within our statistics there is no dependence of {alpha} on x{sub F} for any charm species for the interval 0.1 < x{sub F} < 1.0. The average value of {alpha} for charm production by pion beams is {alpha}{sub meson} = 0.850 {+-} 0.028. This is somewhat larger than the corresponding average {alpha}{sub baryon} = 0.755 {+-} 0.016 for charm production by baryon beams ({Sigma}{sup -}, p).