The first measurements of the transverse momenta {pr) of heavy projectile fragments produced by fragmentation of 1.2-GeV/nucleon La are presented. The momentum distributions of the fragments (Z = 26-56) are Gaussians and broader than predicted by models based on internal momenta of the projectile nucleons. The larger pr observed do not appear to be due solely to Coulomb effects, but are consistent with a simple model whereby nucleons from the (hot) overlap region recoil collectively into the (colder) projectile fragments. Thus pr and the fragment mass may provide a good indication of the vector impact parameter b. PACS numbers: 25.70.NpThere is considerable interest in the hydrodynamic behavior of nuclear matter in violent collisions of relativistic nuclei (RNC). At these energies the colliding nuclei interpenetrate with a velocity larger than the soundpropagation velocity in the nuclear medium. The result is shock compression and heating in the overlap region of the colliding nuclei. x " % In the language of the abrasion-ablation model 9 the overlap region of the abrasion stage is called the participant region, while the remainder of the projectile and target are called spectators. It is believed that the latter receive relatively little momentum in the collision, and that fragment momentum distributions are due largely to internal nucleon momenta. 10 This appeared to be the case in the fragmentation of 12 C and 16 0 at similar energies. n In the experiment reported here we find larger transverse momenta of the fragments than is expected on the basis of internal momenta.Signatures of high compression and collective stopping in RNC are very important. In this regard the transfer of energy from longitudinal to transverse motion and the subsequent (sideways) emission of nuclear matter following compression was one of the first predictions of hydrodynamic calculations. 1 " 7 Early emulsion data 8 and later scintillator array data 12 showed sideways emission of light particles, which was interpreted as evidence for outflow.More complete evidence for shock effects and apparent matter flow in RNC has come from recent global event analyses of light particles emitted into the nearly 4n Plastic Ball/Wall 13 and streamer chamber 14 detectors at the LBL Bevalac. It is found 13 that the mean flow angle increases with event multiplicity and that light particles of near beam rapidity have p' x (pr projected into the reaction plane) per nucleon in the range 0-200 MeV/c. The latter is taken as an indication of projectile fragment "bounceoff." Recent emulsion experiments 15 also detected collective flow. Calculations based on a nuclearfluid (hydrodynamical) model predict the flow-angle data quite well. 16 Microscopic calculations 17 also produce net side splash, and a more recent calculation 18 gives a good fit to flow-angle data. 13 We present here the first measurements of transverse momenta of heavy fragments in RNC. These were produced by the fragmentation of 1.2-GeV/nucleon 139 La nuclei from the Bevalac incident on carbon t...

The (n 9 p) reaction in 6 Li and 7 Li at 60 MeV reveals large structures at high excitations which are the analogs of states in 6 Li and 7 Li at 29 and 31 MeV, respectively. These new structures, which exhibit giant dipole strength, are not seen in photoneutron data. They do not appear to contain appreciable dipole spin-mode strength. The exhaust large sumrule fractions, and largely answer the longstanding question of missing giant dipole resonance strength in these nuclei.

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