First, second, and third moments of gamma-ray multiplicity distributions from deeply inelastic collisions have been measured for the system 86 Kr on 144 Sm at 490-MeV Kr energy. The average gamma-ray multiplicities are ~21, independent of reaction angle and fragment charge. The multiplicity distributions are broad, with standard deviations of v ~ 10, and they have a negative skewness.Deeply inelastic collisions (DIC) are a characteristic feature of heavy-ion reactions at energies above the Coulomb barrier and extensive data on the energy and mass transfer in DIC have been published. 1 We report here on measurements of gamma-ray multiplicity distributions (first, second, and third moments) from DIC at 5.70 MeV/nucleon of ^Kr on 144 Sm as a means of obtaining detailed information on the angular momentum transfers accompanying the energy and mass transport. It will be shown that the average gamma-ray multiplicities are compatible with the sticking limit for DIC while the magnitudes of the second moments of the multiplicity distributions provide a severe challenge for such a simple description of the angular momentum transfer.Previous related publications encompass the fission angular correlations in the 86 Kr + 209 Bi system 2 at 7.1 MeV/nucleon and the measurements of average gamma-ray multiplicities (first moments) of Aleonard et al. 3 ( 86 Kr+ Ag, Ho, Au at 7.2 MeV/nucleon), of Glassel et al. 4 ( 20 Ne+Ag at 8.75 MeV/nucleon), and of Sann et al. 5 ( 86 Kr + 166 Er at 5.9 MeV/nucleon). Second and third moments of gamma-ray multiplicity distributions from DIC have not been reported previously.The 86 Kr beam was provided by the Gesellschaft fur Schwerionenforschung UNILAC. The chargedparticle reaction products were detected in a A£-E telescope with a solid angle of 12.5 msr. The A£ measurement was made with a gas (CH 4 ) ionization chamber and the residual energy was obtained from a semiconductor counter. The &E-E information was transformed to element (Z) and energy information and the resulting Z resolution was Z/AZ^50. Gamma rays were counted in seven 5-cm by 5-cm-diam Nal(Tl) detectors placed in the hemisphere below the scattering chamber at a distance of 12 cm from the target. For each charged-particle event recorded the gamma-ray detectors which fired were recorded; their trigger levels were at ~ 100 keV. From the counting rates in the zeroth, first, second, etc. fold coincidences between the particle telescope and the gamma counters, the gamma-ray multiplicity information was deduced 6 as a function of the fragment energy and Z. Measurements were made at particle-detector angles of 25, 30, 35, 43 (grazing), 50, and 55 degrees with respect to the beam axis.Representative results are shown in Figs. 1 and 2. Figure 1 depicts results as a function of Z for Q^-20 MeV, where Q is the Q value assuming binary kinematics and fragment mass/charge ratios equal to that of the target plus projectile system. The top part shows the Z spectrum at 35° lab. angle. The lower parts of the figure demonstrate the average multip...
Elastic and inelastic scattering of 86 Kr on 208 Pb to discrete states have been measured at 695-MeV bombarding energy and the observed differential cross sections have been analyzed with a coupled-channels calculation. The obtained ion-ion potential differs significantly from those derived from previous poor-resolution experiments on similar systems, but is consistent with a global potential based upon lighter-mass systematics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.