Cooling power pulse tube

The delivery of SCUBA-2 instrument to the JCMT is due for the end 2006. SCUBA-2 cryogenics is based on a dry dilution refrigerator (DR) (see ref. [7]) the main cryostat cooled by pulse tube coolers with 60 and 4 K stages, and the 1K box and detector arrays with DR for 1 K and millikelvin stages. The PT system has a cooling power of 50W at 45K on the first stage and 1.0W at 4.2 K on the second stage. The coolers were chosen for their inherently low vibration levels. 

CUORE detectors will be cooled by a 3He-4He refrigerator with a cooling power of 3mW at 120 mK. Refrigerators with the required characteristics are technically feasible (see Section 6.1). A cryogenic configuration, which allows to keep the 4 K stage temperature constant for the whole duration of the experiment, is foreseen. This solution is based on new commercial pulse tube coolers (see Section 5.8). 

For the cooling of CUORE, it is foreseen the use of five PT 415 (Cryomech) pulse tubes (see Section 5.8). Each pulse tube delivers a cooling power of 40 W at 45 K at the first stage and 1.5W at 4.2 K. The high power requested by the first stages depends on the thermal load from the shields. 

For the total cooling power of 146.3W, at least four pulse tube PT415 are needed. 

Sonicate the suspension of nnclear material in 4 ml aliqnots in a 15-mL conical tube, on ice. Use a microtip attached to a Branson 450 Sonifier starting at setting 4 (six times) then increase to 5 (six times), constant power with a 30-s constant burst, allowing the suspension to cool on ice for 1 min between pulses (see Note 7). 

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