  Scintillating bolometers of ZnSe are the baseline choice of the LUCIFER
experiment, whose aim is to observe the neutrinoless double beta decay of 82Se.
The independent read-out of the heat and scintillation signals allows to
identify and reject alpha particle interactions, the dominant background source
for bolometric detectors. In this paper we report the performances of a ZnSe
crystal operated within the LUCIFER R&D. We measured the scintillation yield,
the energy resolution and the background in the energy region where the signal
from neutrinoless double beta decay of 82Se is expected with an exposure of 9.4
kg x days. With a newly developed analysis algorithm we improved the rejection
of alpha events, and we estimated the increase in energy resolution obtained by
the combination of the heat and light signals. For the first time we measured
the light emitted by nuclear recoils, and found it to be compatible with zero.
We conclude that the discrimination of nuclear recoils from beta/gamma
interactions in the WIMPs energy region is possible, but low-noise light
detectors are needed.
