Electromagnetic dissociation ofCo59andAu197targets by relativisticLa139projectiles

The electromagnetic dissociation of ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ target nuclei by 1.26 GeV/nucleon ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$ projectiles was inferred from measurement of cross sections for the one-neutron removal reaction. The corresponding electromagnetic dissociation cross sections are large, reaching 0.28±0.04 and 1.97±0.13 barns for the ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ ${(}^{139}$La,X${)}^{58}$CO and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ ${(}^{139}$La,X${)}^{196\mathrm{A}\mathrm{u}}$ reactions, respectively. The experimental cross sections in excess of the estimated nuclear contributions are generally well described by use of the Weizsäcker-Williams method for calculating the electromagnetic dissociation contributions, but they appear to increase more slowly as the projectile charge is increased, consistent with a trend observed earlier for lower-Z projectiles.