To cool both the atom beam and the carbon targets, commercial cryogenic cold heads are used.  Both heads form part of a self-contained closed circuit through which compressed helium is pumped.  The head which cools the atom beam is a model RGD210 (10W cooling power at 80K, 2W at 20K), and the head on which the target is mounted is a model RGD1245 (45W cooling power at 80K, 12W at 20K), both manufactured by Leybold.  The pair of cold heads are driven by a single 6kW compressor.

Both heads consist of two cooling stages.  The first stages are cooled to ~35K by expanding compressed helium via the Gifford-McMahon principle.  The second stages, mounted on top of the first stages, are cooled by a similar principle; since they are mounted from a surface which is already chilled to ~35K, the second stages are cooled further to ~10K.  Temperatures are measured using silicon thermodiodes.