Charged-particle multiplicity distributions in pd and pn interactions at 400 GeV/ c

Charged-particle multiplicity distributions in 400-GeV/c pd interactions have been studied in an experiment in the Fermilab 30-inch bubble chamber. From the fractions of odd-prong and backward-proton events, a rescatter fraction of 0.22 +- 0.01 is found (for N > or = 3). The pn multiplicity distribution is obtained from the odd-prong distribution plus a no-cascade assumption. After making one-prong and two-prong estimates, mean charged-particle multiplicities of 9.49 +- 0.12 for pd (including slow particles) and 8.57 +- 0.12 for pn are obtained. In the incident momentum range 100 to 400 GeV/c, pd and pp distributions are very similar to each other and are different from pn distributions.