No description available.

Thesis (M.S.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 53-54). Also available on the World Wide Web.

No description available.

A Dissertation Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg for the degree of Master of Science. Johannesburg March 1975

Thesis (M.S.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references (leaves 44-48). Online version available on the World Wide Web.

Fusion reactions with radioactive neutron-rich projectiles have been the subject of much recent theoretical and experimental interest. Predictions of enhancement of the cross section due to the use of a neutron-rich projectile may have implications for synthesis of heavy nuclei. In this work, the fusion-fission excitation functions were measured for the [superscript 32,38]S + �������Ta reactions. The radioactive �����S beam was produced by projectile fragmentation. In the ����S-induced reaction, an incomplete fusion component was observed at high energies, with average momentum transfer corresponding to escape of an alpha particle. Angular distribution data were used to estimate the quasifission component of the stable-beam reaction. The excitation functions were analyzed using classical and coupled-channels methods; the deduced interaction barriers were 130.7 �� 0.3 MeV and 124.8 �� 0.3 MeV for the ����S- and �����S-induced reactions, respectively. No evidence of any additional mechanism beyond a simple shift in the Coulomb barrier was observed. Taking into account the difference in reaction Q-values, the net lowering of the compound nucleus excitation energy at the barrier is about 12 MeV due to the use of the radioactive neutron-rich projectile; this could significantly affect survival probabilities of heavy nuclei. / Graduation date: 2000

J/psi production is considered a very important probes for studying the properties of quark-gluon plasma (QGP). At the PHENIX experiment at Brookhaven National Laboratory, a large suppression of J/psi production in Au+Au collisions at 200 GeV center of mass energy as compared to the binary collision scaled p+p collisions was observed. The level of suppression is similar to that observed at other energies at CERN's SPS and LHC experiments. This work addresses the PHENIX J/psi measurements at sqrt{s_{NN}}= 39 and 62 GeV Au+Au collisions. These allow for the energy dependent J/psi suppression measurements in order to disentangle the important contributing factors of J/psi production. J/psi results over a wide range of center of mass energies (39-200 GeV) from PHENIX are discussed, in addition to a comprehensive comparison with other experiments.

Cross sections for K-shell ionization by heavy ions have been determined from the measurements of target K x-ray yields. The measurements were performed with Ar, Kr, and Xe ions at energies from 2.5 to 25 MeV/amu and self-supported metallic foil targets of Al, Ti, Cu, Zr, Ag, Sm, and Ta. The x-ray yields were measured with a Si(Li) detector, while the projectile ions were counted in coincidence with the x-rays using a plastic scintillation detector. In addition, the amount of secondary K-shell ionization and the degree of simultaneous L-shell ionization in primary K-shell ionizing collisions were assessed by performing high-resolution x-ray measurements on targets of Al, Ti, V, Co, and Cu with a curved crystal spectrometer. The results of the high resolution measurements revealed that the apparent average Lshell spectator vacancy fraction at the time of Kα x-ray emission, L p , may be represented by a universal function of the Geometrical Model’s parameter X for Z2 = 17 - 32. Multiple-vacancy Kα fluorescence yields and corrections for K-shell ionization by secondary processes were determined with the aid of the high resolution spectra for the targets Al, Ti, and Cu. Fluorescence yields for the other targets were determined using an extrapolation procedure. The resulting K-vacancy production cross sections for 2.5 to 6 MeV/amu projectiles were compared with a limited amount of available experimental data and shown to be in relatively good agreement. The ECPSSR predictions for all the targets except Al agreed reasonably well with experimental cross sections for Ar projectiles. The experimental cross sections for Kvacancy production in Al, Ti, Cu, Zr, and Ag were greatly deviated from the ECPSSR predictions. The cross sections for Kr on Sm and Ta were in good agreement with theory. The scaling properties of the Kα x-ray production cross sections were examined and a semiempirical “universal” curve was deduced that reproduces the measured cross sections to within ±30% on average. The relationship between the Kα x-ray production cross sections and the geometrical model’s universal variable also was examined.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 123-130). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR45983

The present study combines modern jet reconstruction algorithms and particle identification (PID) techniques in order to study the enhancement of proton/pion ratio at mid transverse momentum ([mathematical symbols] 1.5 - 4.0 GeV/c) observed in central Au + Au collisions at [mathematical symbols] = 200 GeV. The ratio enhancement is thought to be caused by recombination processes and/or parton fragmentation modification of jets in relativistic heavy ion collisions. The fragmentation modification hypothesis is tested in this analysis by reconstructing and selecting energetic jets presumably biased to fragment outside of the medium created in Au + Au collisions and comparing their particle composition to the recoiling (medium-traversing) jets. The bias assumption is confirmed by comparing jets in central collisions, where the effect of proton/pion enhancement is present, with peripheral ones where no medium effects are expected. The selected jets are reconstructed by using the anti-k[subscript T] algorithm from the modern FASTJET package. The PID in the p[subscript T] region of interest is possible by combining measurements of the particles' energy deposition and velocity from the Time Projection Chamber and the recently installed (2009-2010) Time of Flight detectors at STAR. The acceptance of these detectors, [eta] < 1.0 and full azimuth, make them extraordinary tools for correlation studies. These features allow for the measurement of relative azimuth ([phi] [subscript jet] - [phi] [subscript pion,proton]) distributions by using the selected jet axis in order to disentangle the uncorrelated background present in the high multiplicity heavy ion collisions. The proton/pion ratios in two different centrality bins and p[subscript T] = 1.2 - 3.0 GeV/c are presented for biased (vacuum fragmenting) jets and their recoiling counterparts / text