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Multifragmentation for 129Xe-induced reactions on several targets (natCu, 89Y, 165Ho, 197Au) has been studied at E A = 40, 50 and 60 MeV . The probability of emitting n intermediate mass fragments is shown to be binomial at each transversal energy and reducible to an elementary binary probability p. For each target and at each bombarding energy, p shows a thermal behavior as demonstrated by linear Arrhenius plots. A nearly universal linear Arrhenius plot is observed at each bombarding energy, independent of target. The sensitivity of p to the Zthreshold points to its physical significance and rules out auto-correlation effects.

Position-sensitive silicon detectors with discrete position output signal levels, which have been developed for heavy ion reaction studies at the Lawrence Berkeley Laboratory are discussed. The detectors, both 300- and 5000- mu m thick, for use in Delta E-E telescopes, use a series of high and low conductivity strips on the detector p/sup +/ contact to produce a position signal with 15 discrete levels. Since the position of the signals from the strips is known, the detectors are self-calibrating against position nonlinearities. Some aspects of the fabrication of both the 300- and 5000- mu m detectors are discussed, along with their operating characteristics. Illustrative experimental results of /sup 139/La-induced reactions on /sup 40/Ca targets are presented. >