Spallation of Cu by 3.9-GeVN14ions and 3.9-GeV protons

Abstract

Relative yields of 35 products extending from ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ to ${}_{}{}^{76}{}_{}{}^{}\mathrm{Br}$ have been measurd for the interaction of 3.9-GeV (278-MeV/amu) ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ions with copper. For purposes of comparison, cross sections of 54 nuclides produced by the irradiation of Cu with 3.9-GeV protons are also reported. Although the over-all patterns of yields for ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ions and protons are qualitatively similar, there are significant differences. In the mass region $37\le A\le 64$, the mass yield curve for ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ions decreases more rapidly with decreasing $A$ than does the proton curve. No difference could be detected in the shapes of the charge dispersion curves. However, the data indicate a small shift ($<0.1Z$ unit) favoring neutron-deficient products near the target in the case of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ions. The mass yield curves appear to have similar shapes from $A\approx 40$ down to $A\approx 24$, but formation of the still lighter products, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ and particularly ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, is favored in the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ irradiation. An observed enhancement of products such as ${}_{}{}^{62}{}_{}{}^{}\mathrm{Zn}$, ${}_{}{}^{66}{}_{}{}^{}\mathrm{Ga}$, and ${}_{}{}^{69}{}_{}{}^{}\mathrm{Ge}$ is interpreted as arising largely from secondary reactions rather than from primary processes which add charge or mass from the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ to the target nuclei. Some discussion of results from this and other experiments with high-energy protons and heavy ions with complex nuclei is presented in terms of the concepts of limiting fragmentation and factorization.