Spallation of 32S ions at ultra-relativistic energies in nuclear emulsion

• Published in: Canadian journal of physics Vol. 82; no. 4; pp. 263 - 275
• Main Authors: El-Nadi, M, Abdelsalam, A, Shaat, E A, Mossa, N Ali, Moussa, Z Abou, Kamel, S, Rashed, N, Osman, W, Hafiz, M E
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.04.2004
• ISSN: 0008-4204; 1208-6045
• DOI: 10.1139/p03-125

Partial production cross sections of electromagnetic breakup of 32 S projectiles at two widely differing energies were measured using an emulsion target. The electromagnetic dissociation represents about 6% and 17% of the total number of nuclear events at E lab /A = 3.7 and 200 GeV, respectively. The experimental electromagnetic cross sections σ exp EMD show an energy dependence that is well reproduced by the Weizsacker–Williams approximation. The value of σ exp EMD at 200A GeV (with γ >> 1) shows a good agreement with that predicted by the combined model of Pshenichnov et al. Examination of the reactions (γ, p) and (γ, He) reveals that the ratio of 1 p/1 He cross sections is close to unity at Dubna energy (3.7A GeV), while it rapidly increases to 3.0 ± 0.6 at CERN energy (200A GeV). In most of the observed dissociation modes, the total kinetic energy of the fragments in the projectile rest frame is lower than 50 MeV. Nevertheless, it is possible that the contribution of excitation modes of the different multipolarities is determining in this region. PACS No.: 25.70