Stephen Takach

Fermilab experiment E769, which took data in the fixed target run of 1987, collected approximately 370 $\times$ 10$\sp6$ events using a 250 GeV mixed hadron beam impinging on a multifoil target of Be, Al, Cu, and W. Equipped for beam identification with a differential Cerenkov counter and a transition radiation detector, E769 acquired a varied data set of triggers from both positive and negative beam species. The goal in gathering this large, varied data set is to study a wide range of topics in the hadroproduction of charm. Using a downstream silicon microstrip detector (SMD) to resolve charm vertices in the events is a major key in realizing this goal. Using a sample of approximately 1300 D$\sp\pm$ and $\rm D\sp0/\overline{D}\sp0$ events obtained from $\pi\sp-$ beam interactions, I measure the shapes of the differential production cross sections in longitudinal momentum fraction $(x\sb{F})$ and in transverse momentum $(p\sb{t}).$ In the range, $0.1<x\sb{F}<0.6,$ the form $(1 - x\sb{F})\sp{n}$ with $n=3.9\pm 0.3$ is a good representation of $d\sigma/dx\sb{F}.$ In the lower $p\sb{t}$ range, $<$2 GeV, the form exp$(-bp\sbsp{t}{2})$ with $b=1.03\pm 0.06$ GeV$\sp{-2}$ is a good fit to $d\sigma/dp\sbsp{t}{2}.$ In the higher $p\sb{t}$ range of 0.8-3.6 GeV, however, the form exp$(-b\sp\prime p\sb{t})$ with $b\sp\prime=2.76\pm 0.08$ GeV$\sp{-1}$ is a better representation of $d\sigma/dp\sbsp{t}{2}.$ Although the shape of the $x\sb{F}$ production distribution does not show any significant leading particle effects, the total production for D$\sp{\pm}$ states has an asymmetry of 0.18 $\pm$ 0.06 which favors D$\sp-$ over D$\sp+.$ Further, the production shapes do not show any significant dependence on the atomic mass of the target materials.