Tyrex-2
Polarised helium-3 filling station
Filling up the spin filter with polarised helium-3
The short film shown here was recorded during the historical experiment of 1996 [1] when the first spin filter was produced and then tested on the ILL neutron diffractometer D3.
(file formats: .mp4 (mp4 - 59 Mi), .webm (webm - 115 Mi))
See how anxious the experimental team is while preparing the very first spin filter bottle prior its installation on the instrument.
- W. Heil (left) and H. Humblot (middle) working on the 3He polariser.
- A series of cells are filled with 0.7 mbar of pure 3He atoms. The discharge applied in the cells put the 3He atoms in a metastable state. A laser light, circularly polarised with its axis parallel to the applied magnetic field, pump the gas and the obtained electronic polarisation is partially transferred to the nuclei through a hyperfine interaction. When enough nuclear-spins have been polarised, the 3He gas is then compressed in a two-stage non-magnetic titanium compressor. We see H. Humblot adjusting the assembly.
- The neutron-spin filter cell is removed from the compressor by W. Heil once filled with the polarised gas under a pressure of several atmospheres. The polarisation remains for a long duration inside the bottle. With the help of T. Roberts, he puts the cell in a special container to transport it to D3 without loss of polarisation.
- W. Heil and H. Humblot carry the filter to the ILL reactor hall, where A. Leadbetter (ILL Director) is anxiously waiting for them at D3.
- F. Tasset, H. Humblot and W. Heil install the 3He spin filter cell inside the Cryopad-II in which they had trapped a magnetic field (Meissner effect). At the time, they had no better magnetostatic cavity for maintaining the 3He polarisation for long times..
- F. Tasset is looking at the ratemeter to get a first estimate of the neutron-beam polarisation.
Reference
1- H. Humblot, W. Heil, E. Lelièvre-Berna & F. Tasset, Neutron News 8 (1997) 27. DOI: 10.1080/10448639708231997