Infrastructure

A dedicated home-made controller with embedded PC has been developed to provide an automatic liquid nitrogen filling system (LN₂) for the Clover detectors. The supply of LN₂ is from a 1000 l dewar (INOX make) which can be periodically (once in 2 days) filled from a larger dewar (20,000 l), kept outside the beam hall. The distribution of LN₂ is done with a four-column manifold catering to sixteen detectors of backward array and another two-column manifold catering to eight detectors of forward array.

Electrically operated cryogenic valves of Jefferson make (1/2″ diameter, normally closed), are employed for controlling the flow of LN₂ to the detectors. These can be operated under software control by the program linserv working in linux operating system. The temperatures at the overflow ports of the Clover detectors and the filling manifolds are measured using platinum resistance thermometers (PT100) and the valves are closed under overfill condition. A graphical user interface (named, fill) enables the user to monitor the filling status of individual detectors. The detectors are filled automatically twice a day.

The electronics for the various subsystems for INGA are mounted on 19″ instrumentation racks powered by UPS with surge protection circuitry. Two racks are used for mounting the LN₂ control valves and two for housing the high voltage supplies for Clover detectors and anti-Compton shields. The energy and timing signals from the detectors are taken to the electronics cabin using RG58 signal cables. The cable ends in the electronics cabin are grouped into three patch panels. RG172 cables are used for the interconnection between the patch panels and the electronic modules.