ROTATING SANDWICH TARGETS OF ISOTOPICALLY ENRICHED LEAD FOR HIGH-INTENSITY HEAVY-ION BEAMS

Targets of 0.7-1.0 mg/cm2 lead (natPb, 206Pb, 207Pb, 208Pb) of large size (44 mm × 15 mm) have been prepared and covered on both sides with C foils of 0.02-0.03 mg/cm2. Due to the higher total hemispherical emissivity of C in relation to Pb the radiation cooling of these targets in an intense heavy ion beam is increased and the target temperature decreased. The targets were mounted on a wheel that rotates in synchronization with the pulsed beam of the accelerator UNILAC at GSI and were irradiated by 1013 s-1 cm-2 Ar ions of 5 MeV/u specific energy without being destroyed by melting. These targets on the wheel sustained an about 15 times higher beam current density than stationary targets. Different modes of rotation are discussed. © 1979.