MiniGRAIL

Gravitational Radiation Antenna In Leiden

Kamerlingh Onnes Laboratory, Leiden University, The Netherlands

Cryogenics

The dewar was designed by us and was fabricated by KADEL Engineering. The outer diameter is about 1 meter and the cryostat is 3 meters high. The upper part of the cryostat contains the helium and nitrogen reservoirs. The bottom part of the cryostat consists of three radiation shields at 4 (indium seal), 77 and 300 Kelvin. The volume of the nitrogen and the helium reservoirs are 200 and 340 litres respectively. The helium evaporation rate is about 1 litre/hour. Helium transfer will be needed once a week unless we could decrease the evaporation by for instance, using a pulse-tube-refrigerator (PTR) to compensate for part of the losses. Four clear shot tubes give access to the IVC (Inner Vacuum Can). Two of them, with a diameter of 19 mm will be used for the wiring of the dilution refrigerator and for the input of the forced helium flow, that can be used for rapid cooling down to 4.2 K . The two 60 mm diameter feed-throughs will be used as the 1 K pot pumping tube and as a feed through for the SQUID wiring. The fifth tube will be used to guide the 3He pumping tube.

Properties:

Weight empty dewar	800 kg
Nitrogen Reservoir	200 liters
Helium Reservior	340 liters
Evaporation Rate	1 liter/hour