Engineering topics
Publications and source records attributed to Norbury, John W..
Calculations are presented for electric quadrupole excitations in relativistic nucleus-nucleus collisions. The theoretical results are compared to an extensive data set and it is found that electric quadrupole effects provide substantial corrections to cross sections, especially for heavier nuclei.
The first complete calculations of electric quadrupole excitations in relativistic nucleus-nucleus collisions are presented herein. Neutron emission from Y-89 is studied and quadrupole effects are found to be a significant fraction of the cross section.
Previous analyses of the comparison of Weizsacker-Williams (WW) theory to experiment for nucleon emission via electromagnetic (EM) excitations in nucleus-nucleus collisions were not definitive because of different assumptions concerning the value of the minimum impact parameter. This situation is corrected by providing criteria that allows definitive statements to be made concerning agreement or disagreement between WW theory and experiment.
The Coulomb dissociation contributions to fragmentation cross sections in relativistic heavy ion collisions, where more than one nucleon is removed, are estimated using the Weizsacker-Williams method of virtual quanta. Photonuclear cross sections taken from experimental results were used to fold into target photon number spectra calculated with the Weizsacker-Williams method. Calculations for several projectile target combinations over a wide range of charge numbers, and a wide range of incident projectile energies, are reported. These results suggest that multiple nucleon knockout by the Coulomb field may be of negligible importance in galactic heavy ion studies for projectiles lighter than Fe-56.
General formulas for calculating the interactions of galactic cosmic rays with target nuclei are presented. Methods for calculating the appropriate normalization volume elements and phase space factors are presented. Particular emphasis is placed on obtaining correct phase space factors for 2-, and 3-body final states. Calculations for both Lorentz-invariant and noninvariant phase space are presented.
Linear and harmonic potential models are used in the nonrelativistic Schroedinger equation to obtain article mass spectra for mesons as bound states of quarks. The main emphasis is on the linear potential where exact solutions of the S-state eigenvalues and eigenfunctions and the asymptotic solution for the higher order partial wave are obtained. A study of the accuracy of two analytical energy level formulas as applied to heavy mesons is also included. Cornwall's formula is found to be particularly accurate and useful as a predictor of heavy quarkonium states. Exact solution for all partial waves of eigenvalues and eigenfunctions for a harmonic potential is also obtained and compared with the calculated discrete spectra of the linear potential. Detailed derivations of the eigenvalues and eigenfunctions of the linear and harmonic potentials are presented in appendixes.
A computer subroutine parameterization of electromagnetic dissociation cross sections for nucleus-nucleus collisions is presented that is suitable for implementation in a heavy ion transport code. The only inputs required are the projectile kinetic energy and the projectile and target charge and mass numbers.
Simple parameterizations of Coulomb dissociation cross sections for use in heavy-ion transport calculations are presented and compared to available experimental dissociation data. The agreement between calculation and experiment is satisfactory considering the simplicity of the calculations.
Arguments are presented for the possible existence of antinuclei of charge Absolute Value of Z greater than 2 and particularly galactic cosmic antinuclei. Theoretical antinucleus-nucleus optical model cross sections are calculated and presented for the first time. A brief review of the nucleon-antinucleon interaction is also presented and its connection with the antinucleus-nucleus interaction is made. The predicted cross sections are smooth and show no structure. Finally, the findings are tied together with the formation of microlesions in living tissue.
An abrasion-ablation T-matrix formulation is applied to the calculation of double differential-cross sections in projectile fragmentation of 2.1 GeV/nucleon O-16 on Be-9 and 86 MeV/nucleon C-12 on C-12 and Ag-108. An exponential parameterization of the ablation T-matrix is used and the total width of the intermediate states is taken as a parameter. Fitted values of the total width to experimental results are used to predict the lifetime of the ablation stage and indicate a decay time on the order of 10 to the -19th power sec.