Electromagnetic dissociation of 3.7 A GeV ~(16)O in nuclear emulsion

摘要

The electromagnetic dissociation (ED) of 3.7 A GeV 16O in nuclear emulsion is investigated with high statistics. It is found that the electromagnetically dissociated cross section increases with increasing beam energy, the charge distribution of projectile fragments is the same as the results at 60 and 200 A GeV and the production probability of projectile fragments with charge 3 ≤ Z ≤ 5 is less than that of the other projectile fragments. These results can be well explained by use of Weizsacker and Williams method for calculating the ED contributions. The percentile abundance of various decay modes for ED at 3.7 A GeV is close to the result at 60 and 200 A GeV, but it is different from the result at 14.6 A GeV. The ED of 3.7 A GeV is mainly caused by the giant dipole and quadrupole resonance of E1 and E2, which can be qualitatively explained by the multiplicity distribution of projectile proton in ED. The multiplicity distribution of the fragments in ED and nuclear events have different functional forms. This difference may be a consequence of the different reaction mechanism involved.