The fragmentation of 1.2 GeV per nucleon La-139 nuclei has been studie
d. Total charge changing cross sections for H (CH2.-C), C, and Pb targ
et nuclei, and elemental production cross sections for C and CH2 targe
ts for 1 less-than-or-equal-to DELTAZ less-than-or-equal-to 30 have be
en measured. For heavy projectile fragments, the projected transverse
momenta extracted are generally larger than predicted by models based
on the internal momenta of nucleons in nuclei. Fits to the heavy fragm
ent momentum distributions yield additional transverse momenta or ''bo
unce-off'' which range from congruent-to 500 to 1000 MeV/c.