The Spin Polarised Hot Neutron Beam Facility

First experiment with the 3He neutron spin filter

During this first test of an 3He neutron spin filter, the neutron-beam polarisation transmitted by the filter could be determined with high accuray from spin dichroism measurements. It was verified that no significant relaxation was induced by neutron capture and that the wavelength variation of the polarisation down to 0.33Å was in good agreement with the 1/v dependency of the absorption cross-section.

The team: E. Bourgeat-Lami, H. Humblot, W. Heil, F. Tasset

  • The cell filled with polarised 3He arrives on D3. The transport container includes two magnetic coils which maintain the polarisation. H. Humblot, F. Tasset, W. Heil and E. Bourgeat-Lami are busy around it.
  • F. Tasset transfers the cell into CRYOPAD which provides a homogeneous magnetic field and also acts as a spin flipper.
  • The movie ends with a short presentation of the zero-field polarimeter developped at PNPI (Gatchina, Russia). This polarimeter is capable of measuring very small rotations of the neutron polarisation.

(movie recorded by E. Lelièvre-Berna, ILL, 1996)