Design and application of multi-loop capillary heat pipes to cool GAPS silicon detectors

This paper presents the basic design of a thermal control system that can cool the >1000 semiconducting silicon detectors for the General Anti-Particle Spectrometer (GAPS) balloon-borne cosmic antiparticle mission. To identify antiparticles with sufficient energy resolution, it is essential to cool the detectors to operating temperatures below −40°C. To provide such cooling, we developed a novel multi-loop capillary heat pipe (MCHP) which merges gravitational force, capillary force, and self-oscillating driving force to flow a refrigerant effectively in thin tubes. The MCHP is suitable to cool a number of widely distributed detectors with a minimum mass, minimum power consumption, and large thermal conductivity, compared to any other techniques such as traditional pumped circulating systems. Experimental results using a two-meter-scale full-size model verified that the MCHP can meet all the requirements. The unique MCHP technique can be applied to thermally controlling other large particle/nuclear instruments.