Recoil energies of fragments photoproduced in Cu, Ag and Au

The recoil energies of24Na produced in Cu, Ag and Au and of a series of fragments produced in Cu irradiated with 800 MeV bremsstrahlung have been measured in directions forward, backward and perpendicular to the beam using the thick target-thick catcher method. Comparison of the measured values with theoretical calculations indicates that24Na is produced through fission in Ag and Au and that fission is competing with spallation even in Cu.