Roy Crawford Lemmon

Direct observation of the inversion of flow

Abstract The sign of the mean transverse momentum of non-equilibrium light charged particles was determined from the circular polarization of coincident γ-rays emitted from residual nuclei for 14 N-induced reactions on 154 Sm at incident energies, E/A=35, 100 and 155 MeV. Results of the emitted α-particles at mid-central collisions show the predicted transition from mean-field dominated dynamics at low energies to nucleon-nucleon collision dominated dynamics at high energies.

Isospin independence of the H-He double isotope ratio "thermometer"

Abstract Light fragments ( d , t , 3 He, 4 He) were measured for central collisions of 112 Sn+ 112 Sn and 124 Sn+ 124 Sn at E / A =40 MeV. While individual isotope ratios depend strongly on the neutron-to-proton ratio of the entrance channel, the double ratio R H–He =[ Y ( d ) Y ( 4 He)]/[ Y ( t ) Y ( 3 He)] shows no such sensitivity. Within the assumptions of the Albergo thermometric technique, this independence is consistent with the attainment of full chemical equilibrium for each reaction at the same common temperature. However, the same independence is also predicted by calculations based on emission from an expanding emitting source, where the yield for the final double ratio is not obtained at a single well defined source temperature.