This Dilution Refrigerator located at the CSNSM is a classical dilution unit incorporating sintered silver heat exchangers and a large pumping system (40 m3/h rotary pump and 400 l/s turbo pump in He). It can achieve reasonably high 3He flow rates, thus providing the cooling power needed by massive 0νββ detectors. The dilution unit is coupled to a pulse-tube refrigerator, consisting of the commercial unit PT-405 manufactured by Cryomech. This model provides a cooling power of 25 W at 55 K at its first stage, and 0.3 W at 3.5 K at its second stage.
The EDELWEISS cryostat is located in the Laboratiore Souterrain de Modane (LSM), France. The laboratory is located under the Frejus mountain and it is one of the deepest underground laboratory: above there is1780 m of rock (4800 m water equivalent).
The EDELWEISS setup consists in a special upside down dilution unit with LHe as the first cooling stage. It is actually a hybrid machine with a pulse tube refrigerator used to decrease the LHe consumption of the main bath. The head of the cryostat has a large experimental volume of 50 l and is placed in a ISO class 4 clean room.
The experimental volume is shielded from the radioactive environment by 10 cm of copper and 20 cm of lead. Pure nitrogen gas is circulated around the cryostat in order to reduce radon accumulation. All the electronic components were moved away from the detector and hidden behind a 7 cm thick Roman lead shield. A polyethylene shield of 50 cm is placed outside the lead shield. An active muon veto covers the entire setup with a 98% geometry efficiency.
The data acquisition system is based on AC electronics with cold pre-amplifiers at the 4 K stage.