Liquid Nitrogen

Gammasphere's detectors use germanium that needs to be kept at a specified temperature to stay intact. For this reason, Gammasphere uses liquid nitrogen within each detector to maintain the thermal requirement. Each detector has a nitrogen tank that is filled daily, a process that is completed through something called an LN system, where a large tank gives gaseous nitrogen and given to “solenoids” that provide a valve to control the flow of nitrogen to each detector as liquid nitrogen. The system is controlled through the VME computer, and completes this process for Gammasphere detectors at least twice daily. If a detector leaks or loses the necessary temperature level at any point, an alarm sets off.