Previous analyses of the comparison of Weizsacker-Williams 0 theory to experiment for nucleon emission via electromagnetic (EM) excitations in nucleus-nucleus collisions have not been definitive because of different assurnptions concerning the value of the minimum impact parameter. This situation is corrected by providing criteria that allow one to make definitive statements concerning agreement or disagreement between WW theory and experiment. PACS: 25.70. N,

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... 19890019795 2018-07-24T18:45:53+00:00Z -Collisions between relativistic nuclei can oxur via the Strong or Electromagnetic interaction. There is an enormous literature on processes induced by the Strong force*), but relatively few studies have been carried out on the Electromagnetic (EM) aspects of relativistic nucleus-nucleus collisions. 2-23 This situation is surprising given the richness of applications of EM effects. These effects are of importance for the following reasons: i) EM interactions between relativistic nuclei are interesting in their own right; ii) they will form a significant background to the formation of a quark-gluon plasma at ultrarelativistic energies; iii) other applications in physics such as subthreshold pion production 3) iv) astrophysical applications 4); v) interference effects between Strong and EM amplitudes 5); vi) studies of virtual photon theory 49 6-10) and vii) applications in space radiation effects 11) Bertulani and Baur 25) have written an outstanding review article on EM effects in nucleusnucleus collisions to which the reader is referred. The present paper is concerned with nucleon emission via electromagnetic dissociation in relativistic nucleus-nucleus collisions. The fiist experiment of this kind was performed by Heckman and Lindstroml5) looking at excitations in 1% and l60 projectiles at energies of 1.05 and 2.1 GeV/N on a variety of targets (l*C, 27Al, @Cu, 108Ag, 208Pb). Measured EM cross sections for iiucleon emission ranged from 0 to 50 mb. Olson et al 13) later measured excitation of 180 projectiles at 1.7 GeV/N on 48Ti, 208Pb and 23813 with cross sections up to 140 mbl. Studies of 197Au and 59Co target excitation were later reported with CroSfj sections all the way up to 1970 mb for 139La projectiles at 1.26 GeV/N. Lighter projectiles were also used 149 20-23) w i t h smaller cross sections. All studies mentioned so far have been for projectile energies less than or equal to 2.1 GeV/N. The measurements were made at the Berkeley Bevalac. However, some very interesting measurements have also been made for 197Au target excitation at the CERN SPS using 160 projectiles at 60 and 200 (3eV/N with cross sections of 820 and 440 mb respectively. All the above data is sumniarized in Tables 1 and 3.