The spallation target of the ultra-cold neutron source UCN at PSI

A new type of ultra-cold neutron source, based on the spallation process, is scheduled to start operation at PSI in 2008. The UCN source will be operated in a pulsed mode using the 1.2 MW (590 MeV, 2 mA) proton beam delivered from the ring cyclotron. In this paper we discuss the neutronic and the thermo-mechanical behavior of the target assembly under pulsed operation.