Preparation

• Pump main vacuum through valve (V) with a turbo pump, ideally over night. If the cryostat was cold recently a few hours will be o.k., but if water might be condensed inside, it should be pumped for several days.
• Connect sample space, helium reservoir etc. (all volumes which will contain liquid or gaseous helium) with a raw vacuum pump. Flush 2 times with helium gas. Check the function of cold valve (C) and warm valve (W). Pump sample space.
• Fill in liquid nitrogen. Ideally wait one night.
• Fill in liquid helium.

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Insert Sample

• Increase the temperature of the heat exchanger to 100 K.
• Connect a helium gas tube to the sample space and wait until 1 bar is reached inside.
• Remove cover.
• Enter the sample stick slowly and screw the top.
• Pump down and flush again with He gas, then pump down to a pressure between 10 and 50 mbar.

Cool down

There are two possibilities, each has advantages and drawbacks.

• With He pump

• Connect helium pump to the pumping port (P). Switch on the pump and wait until the pressure stabilizes (should be less than a few millibars). Make sure that the warm valve (W) is closed, open cold valve (C) a little, the pressure at the pump should not exceed 40 mbar (20 on the ILL cold valve controller).
• Put a setpoint of 10 K on the heat exchanger.
• When the heat exchanger is at 10 K and the sample near 10 K, reduce the pressure by closing the cold valve gradually until the heating power the temperature controller needs to keep 10 K has reached a value between 100 and 200 mW. Wait half an hour and check or change the cold valve setting again.
• Put the temperature setpoint to zero. The cryostat should cool to 1.6 K within 10 minutes.

• With warm valve

• Open cold valve (C), open warm valve (W) by about 3 turns. Close the valve (R) going to the He recovery.
• When the heat exchanger and the sample temperature have stabilized around at 4.2 K, close the warm valve and reopen a little bit, just enough to held 4.2 K.

Remove Sample

• Increase the temperature of the heat exchanger to 100 K.
• Connect a helium gas tube to the sample space and wait until 1 bar is reached inside.
• Remove the stick slowly and put the cover.
• If no new sample is entered soon, pump down the sample space to at least 10 mbar.
• Dry the sample stick.