Other innovative techniques 279Figure 8.4.Exclusion plots (90% C.L.) and DAMA evidence.to resolve the dilemma could come from the much larger underground set-up that
CDMS is going to operate in the near future and from the DAMA upgrading in
terms of total detector mass.
8.4 Other innovative techniques
There are many mid-term projects which are not based on a phonon readout
channel but which, however, point to a substantial increase in sensitivity to
neutralino interactions. I shall mention here, for lack of space, only three projects.
This selection was admittedly also made on the basis of personal taste, besides
scientific relevance. For a complete review, I suggest the reader refers to the
proceedings of a recent specific conference, for example [30].
The DRIFT experiment [31] represents the only attempt to detect the
direction of the nuclear recoil already at a test-phase. It consists of a low-pressure
TPC using a 20 Torr Xe–CS 2 gas mixture. Such a device must be able to detect the
tiny tracks from nuclear recoils with less than 1 mm track resolution. In addition,
large detector masses are necessary. This requirement suggests that the magnetic
field should be abandoned, with a consequent deterioration in the space resolution
due to enhanced diffusion. In order to solve this problem, the new concept