The fragment momentum distributions in the projectile rest frame are, typically, Gaussian shaped, narrow, consistent with isotropy, depend on fragment and projectile, and have no significant correlation with target mass or beam energy. The nuclear temperature is inferred from the momentum distributions of the fragments and is approximately equal to the projectile nuclear binding energy, indicative of small energy transfer between target and fragment.We present here the first definitive measurements of the momentum distributions for isotopes produced by the fragmentation of heavy-ion beams at the Lawrence Berkeley Laboratory Bevatron c These results apply to the fragmentation of 12 C nuclei with energies 1.05 and 2.1 GeV/ nucleon, and le O at 2.1 GeV/nucleon. The evaluation of the isotopic production cross sections given by Lindstrom et al. 1 is based on these data. The momentum and cross-section measurements were performed with use of a single-focusing magnetic spectrometer with a half-angle acceptance of 12.5 mrad about zero degrees. 2 Targets were Be, CH 2 , C, Al, Cu, Ag, and Pb. The charge and mass of the fragments were obtained by measuring their rigidity {Pc/Ze), energy loss in solid-state detectors, and time of flight. Particle trajectories were determined with multiplewire proportional chambers. The longitudinal and projected transverse momenta, P" and P ± , were obtained from the rigidity and direction of the particle at the focal plane of the spectrometer. The rigidity range was scanned in 0.

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