  Bunch-by-bunch longitudinal diagnostics is a key issue of modern
accelerators. To face up this challenging demand, tests of mid-IR compact
uncooled photoconductive HgCdTe detectors have been recently performed at
DAFNE. Different devices were used to monitor the emission of e- bunches. The
first experiments allowed recording of 2.7 ns long e- bunches with a FWHM of a
single pulse of about 600 ps. These results address the possibility to improve
diagnostics at DAFNE and to this purpose an exit port on a bending magnet of
the positron ring has been set-up. An HV chamber, hosting a gold-coated plane
mirror that collects and deflects the radiation through a ZnSe window, is the
front-end of this port. After the window, a simple optical layout in air allows
focusing IR radiation on different detectors. The instrumentation will allow
comparison in the sub-ns time domain between the two rings and to identify and
characterize bunch instabilities. Moreover, to improve performances tests of
new photovoltaic detectors with sub-ns response times are in progress. We will
briefly summarize the actual status of the 3+L experiment and will discuss
future applications of fast IR photovoltaic detectors and the development of
fast IR array detectors.
