Development of a Mechanically Pumped Two-Phase CO₂ Cooling Loop for the AMS-2 Tracker Experiment

The Alpha Magnetic Spectrometer AMS-2 is planned for a five years mission as attached payload on ISS, the International Space Station. It is an international experiment searching for anti-matter, dark matter, and missing matter. AMS-2, an improved version of AMS-1 flown on STS 91, consists of various particle detector systems, one of these being the (Silicon) Tracker. The trade-off based choice and the experimental feasibility demonstration of a mechanically pumped two-phase CO₂ cooling loop for the Tracker is discussed in detail. The current status and ongoing and planned development activities are discussed.