As regards the SEOP technique, alternative alkali metals such as potassium, sodium and lithium must be investigated. There is experimental evidence that the spin-exchange rate is an order of magnitude higher for potassium, which should be an excellent opportunity to raise the 3He polarisation. However, because of the stronger reactivity of the lighter alkali metals, the development work will be diffcult and time-consuming. Partner P3 will develop the techniques for optimising the continuous optical pumping of 3He at the same time it is functioning as a spin filter on a neutron beam.

Even if the dipolar relaxation accelerates the polarisation decay, higher pressures must be envisaged as they would allow researchers to carry out experiments which necessitate hot neutrons (< 0.8 Å) or very opaque spin filters. In order to compensate for the dipolar relaxation, we anticipate a gas flow apparatus which would also permit using two kinds of 3He containers, one being perfectly transparent to the light and the other to the neutron beam. This development will benefit from the experience acquired with MEOP compressors.

Partners P3 and P5, together with observers O1 and O2, have a long experience in polarising Xenon and 3He with the SEOP technique. Partner P5 has already a collaboration with observer O2 and has made progress in developing a laboratory SEOP system. All together, these participants will contribute to the development and production of a prototype system for a neutron scattering instrument.

Here are the main objectives:

• Develop SEOP pumping station, trial experiments on the ISIS pulsed neutron source and the FRJ-2 Research Reactor,
  
• Exploration of SEOP using Rb and K to improve maximum polarisation. Development of a prototype double-cell, on neutron beam optical pumping SEOP system,
  
• Development of SEOP systems using Rb and K to polarise 3He continuously during neutron experiments,
  
• Neutron beam testing and development during neutron experiments.