Differential fragmentation cross sections for 7.3 GeV nitrogen ions incident on protons

Abstract

Differential cross sections $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}$ for the inclusive reaction $^{14}\mathrm{N}$ + $p\ensuremath{\rightarrow}Z$ + anything (for $3\ensuremath{\le}Z\ensuremath{\le}6$) have been measured at six laboratory production angles ($\ensuremath{\theta}<5\ifmmode^\circ\else\textdegree\fi{}$) for 7.3 GeV nitrogen ions interacting in liquid hydrogen. The angular distributions for C, B, and Be fragments decrease sharply with increasing angle, as expected for this type of peripheral reaction. The corresponding transverse momentum (${p}_{t}$) distributions for these fragments can be represented by Gaussian functions of ${p}_{t}$. The Li distribution appears to be non-Gaussian, suggesting one (or more) different production mechanisms. The dependence of the widths of the momentum distributions on fragment mass is not consistent with theoretical predictions, and shows some evidence for an "effective" number of nucleons which determine the fragmentation spectrum of the nitrogen nucleus. Integration of the angular distributions gives partial production cross sections which are consistent with results at higher energy. This energy-independent behavior implies that limiting fragmentation is applicable down to energies of 0.5 GeV/nucleon.NUCLEAR REACTIONS Relativistic heavy ions; fragmentation of 7.3 GeV nitrogen on protons.