D. J. Morrissey

Bio: D. J. Morrissey is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Angular momentum & Nucleon. The author has an hindex of 7, co-authored 15 publications receiving 138 citations.

Target residues from the reaction of 8 GeV Ne 20 with Ta 181 and Au 197

Abstract: The cross sections for the production of 99 different target fragments from reactions of 8.0 GeV $^{20}\mathrm{Ne}$ with $^{181}\mathrm{Ta}$ and $^{197}\mathrm{Au}$ were measured. The target fragment radioactivities were measured by off-line gamma-ray spectroscopy. Details of the measurement as well as the calculation of the independent isotopic production cross sections and the integrated mass yields are given. Comparisons of these data to previously reported data for proton induced reactions show that the target residue production cross sections scale with the total projectile kinetic energy, not velocity. The total cross section for residue production indicates that some products result from collisions with significant overlap of the central densities of the two nuclei, in contrast to results obtained with low mass targets. Comparisons of the data with a Monte Carlo cascade calculation and an abrasion-ablation calculation verify the importance of ground state correlations of the neutrons and protons on the fragmentation isotopic cross sections.NUCLEAR REACTIONS $^{181}\mathrm{Ta}$($^{20}\mathrm{Ne}$, spallation), $^{197}\mathrm{Au}$ ($^{20}\mathrm{Ne}$, spallation), $E=8.0$ GeV; measured radionuclide production cross sections and isobaric yields; comparison to proton induced spallation of $^{181}\mathrm{Ta}$ and $^{197}\mathrm{Au}$; comparison to abrasion-ablation and Monte Carlo cascade models for residue production; Ge(Li) spectroscopy, radioanalytical mass and charge distributions; relativistic heavy ion nuclear reactions.

Rise and Fall of the Spin Alignment in Deep-Inelastic Reactions

Abstract: Both the magnitude and alignment of the transferred angular momentum in the reaction {sup 165}Ho + {sup 165}Ho have been measured as a function of Q value via continuum {gamma}-ray multiplicity and anisotropy techniques. Two regimes are observed: A low-Q-value regime where the aligned angular momentum component dominates over the random components, and a large-Q-value regime where the random components dominate and decrease the spin alignment.

Target fragmentation of Au and Th by 2.6 GeV protons

Abstract: Target residues from the reaction of 2.6 GeV protons with gold and thorium nuclei have been studied with radiochemical techniques. Chemical separations were used to enhance the sensitivity for detecting target residues in the near-target region. These data are compared to a new empirical parametrization of the mass and charge yields of fragmentation, or spallation, products based on a comprehensive analysis of data in the literature. Data include results from both projectile and target fragmentation studies. The new near-target residues provide significant new insight into the variation of the cross sections of products near in mass to the target (or projectile). The results of this study and the empirical description are compared to the internuclear-cascade model of these reactions.

High-energy nuclear collisions

Abstract: Until recently the properties of nuclear matter at high densities ϱ > ϱ 0 = 015 fm-3 and/or temperatures T > B 0 = 16 MeV have been inaccessible for study experimentally This is because normal nuclei saturate at one density, ϱ ≈ ϱ 0, with a unique volume energy per nucleon, —B 0 In the past, nuclear properties have been studied either with elementary probes such as electrons, pions, and protons, or with low-energy nuclear probes Such probes, however, cannot compress entire nuclei nor heat them up to T > B 0 Thus, these probes have been unable to shed light on this aspect of nuclear matter In nature gravity can crush nuclear matter to high densities in the hearts of neutron stars Also, supernova collapse may involve high densities and temperatures before exploding However, it is clear that the properties of dense nuclear matter are very difficult to extract from the limited observations of such objects

Mass-yield distribution in proton and heavy ion induced target fragmentation processes

Abstract: It is shown that nuclear target fragmentation in proton and heavy ion induced reactions, in particular the following experimental facts concerning the mass-yield distribution can be understood in terms of a semiclassical model:(i) its independence on the mass of the projectile at approximately the same incident energies,(ii) its trend of approaching a limit at higher bombarding energies,(iii) its “U-formed” shape at sufficiently high bombarding energies. Standard methods in statistical theory of chemical equilibrium are used to calculate the mass-yield distribution for medium and heavy target nuclei in high-energy nuclear reactions where the Coulomb interaction between the fragments is taken into account selfconsistently. The result shows: The fact that the decaying rest target nucleus and its fragments are bounded objects of finite size and finite charge have significant influences, especially on the form of the mass-yield distributions.