  In the framework of the ``ULTIMA'' project, we use ultra cold superfluid 3He
bolometers for the direct detection of single particle events, aimed for a
future use as a dark matter detector. One parameter of the pulse shape observed
after such an event is the thermalization time constant. Until now it was
believed that this parameter only depends on geometrical factors and superfluid
3He properties, and that it is independent of the nature of the incident
particles. In this report we show new results which demonstrate that a
difference for muon- and neutron events, as well as events simulated by heater
pulses exist. The possibility to use this difference for event discrimination
in a future dark matter detector will be discussed.
