Nuclear and electromagnetic fragmentation of 2.25-TeV197Au nuclei

Abstract

Abstract.We report the first measurement of the total charge-loss cross section Gtot=aem+anuo and partial cross sections (for AZ = 1, 2, ... After presenting our data, we focus on the problem of disentangling two modes of high-energy nucleus-nucleus interactions -a nuclear mode which takes place when a relativistic projectile and a target pass each other within the range of the strong force and an electromagnetic mode which occurs at larger impact parameters such that only the virtual photons from either the target or the projectile can interact with the other. Particle telescopes [2][3][4][5][6][7], plastic track detectors [8][9][10][11][12], and nuclear emulsions [13,14] have been used to separate nuclear and electromagnetic contributions to charge-changing interactions of projectiles, and gamma-ray spectroscopy [15][16][17][18] and particle telescopes [2,3,7,19] have been used to study nuclear and electromagnetic processes in which neutrons are emitted from a target. In all these experiments it is assumed that, if the impact parameter is less than a critical value, roughly the sum of radii of projectile and target, the interaction is purely nuclear; if not, it is purely electromagnetic. In this view the cross section is the sum of the two contributions:

Charge-changing fragmentation of 10.6 GeV/nucleonAu197nuclei

“…The total cross sections can also be compared to those measured by Hirzebruch et al [6] and He and Price [7] using BP-1 glass track detectors with similar Au projectiles &om the AGS. This comparison is shown in Fig.…”

“…Taking the ratios of the low-and high-energy cross sections emphasizes the differences; the ratios for carbon are shown in Fig. 7 [6] and He and Price [7] as a function of the mass of the target. experiment to measure cosmic-ray abundances, the effects of these differences on the abundances deduced at the top of the atmosphere will be considerable.…”

“…The ratios of the predicted to the measured cross sections are graphed in Fig. 10 Both Hirzebruch et al [6] and He and Price [7] tic energies the electromagnetic contribution to the total interaction cross section can exceed the nuclear contribution [16]. However, charge changi ng ele-ctromagnetic dissociation (EMD) has not been studied thoroughly for UH nuclei, where the high Coloumb barrier should be an impediment [17,18].…”

“…These cross sections have been compared directly to lower energy cross sections measured at the Bevalac, as well as to cross sections measured in etchable glass detectors by Hirzebruch et al [6] and He and Price [7] using similar, approximately 10 GeV/nucleon is~Au beams. The partial cross sections in hydrogen have also been compared to those predicted by the semiempirical calculations of Silberberg and Tsao [8], often used in models of cosmic-ray propagation.…”

Inclusive meson production in peripheral collisions of ultrarelativistic heavy ions

“…[33]. This estimation does not take into account the energy dependence of the total nucleus-nucleus cross section due to the increase of the total nucleonnucleon cross section.…”