Nuclear dependence of high- x sub t hadron and high-. tau. hadron-pair production in p - A interactions at radical s =38. 8 GeV

We present a high-statistics, species-identified measurement of the W-to-Be per-nucleon cross-section ratio, {ital R}{sub W/Be}, for high-{ital x}{sub {ital t}} hadrons and high-{tau} {ital h}{sup +}{ital h{minus}} pairs produced in {ital p}-{ital A} collisions at {radical}{ital s} =38.8 GeV. The data extend to 0.62 in {ital x}{sub {ital t}} and 0.39 in {radical}{tau} . For single hadrons, {ital R}{sub W/Be} peaks at {ital p}{sub {ital t}}{approx}5 GeV/{ital c} and decreases to {approx}1 for mesons with {ital pt}{gt}8 GeV/{ital c}. At fixed {ital p}{sub {ital t}}, {ital R}{sub W/Be} falls with {radical}{ital s} . For symmetric pairs with {radical}{tau} {gt}0.28, {ital R}{sub W/Be}=0.84{plus minus}0.02{plus minus}0.07, suggesting a nuclear suppression of high-{ital z} fragmentation. {ital R}{sub W/Be} increases with {ital p}{sub out}, indicative of constituent multiple scattering.