The Ranicon (``Resistive Anode camera'', described in Clamping and Paresce (1989)) has been built by the Space Telescope Science Institute (Baltimore). The model we used was graciously lent by the Observatoire de la Côte d'Azur (OCA) for some observing runs between 1993 and 1996.
This detector has a S20 photo-cathode and a saturated mode single microchannel amplifier (Gen II). The position analysis of the detected photo-events is made with a resistive anode. Each cloud of amplified electrons, resulting from the impact of a photon on the photo-cathode, produces a charge drift towards the four electrodes which surround the resistive anode. The location of the impact is deduced from the voltage variations et the electrodes and can be measured accurately to about 10 kHz.
The image intensifier of the Ranicon is cooled with a Peltier system which is itself cooled by the circulation of water and glycol. During the observing runs at TBL, a closed circuit was used. The heat was dissipated by letting a part of the circuit lay on the cooled floor of the dome.
Compared to the CP40, the quantum efficiency of the Ranicon is smaller by a factor of three. This is due to the lower efficiency of the GEN II compared to the GEN I intensifiers.
Although the micro-channel amplification does not introduce geometric distortion, we have noticed a small distortion with the X and Y axes which are not perfectly perpendicular. A small variation of the geometric scale was also noticed and calibration was needed during the night. Both effects must be caused by some bad tuning of the resistive anode detection.
Another unexpected defect was the presence of a small ``hole'' at the center of the autocorrelation function, similar in some way to that of the CP40 (cf, §4.2), but with a smaller amplitude. This is caused by the depletion of electrons of a micro-channel after a photon-detection: a delay of a few dozens of milliseconds is needed to recover its full charge and efficiency. To reduce this defect, we found that the photon flux had to be lowered to about 8000 photons/sec.