After coming back home in the integration room building 867 at CERN, AMS will undergo magnets replacement. The vacuum chamber which contains the cryostat which maintains the magnet near the absolute zero is now warming up.
Initially about 1,000 litres of superfluid Helium had to be removed. Very carefully, the SF Helium was warmed to 4 K and then pumped out while evaporating. During this step it is important to check that cryostat’s different parts have a temperature difference not exceeding 30 K, otherwise some stress could result and damage the mechanical structure.
This two-weeks heating process will end next week. Why do we need to warm up the experiment? Only when the vacuum chamber and its contents are at room temperature, it will be possible to replace it with the “flight spare” chamber embodying the permanent magnet. Both, the “flight spare” chamber and the permanent magnet, will arrive at CERN from Aachen RWTH I. Physikalisches Institute, in Germany around May 15th. We’re waiting for them!