The most efficient means for increasing the flux of neutrons is the use of advanced focusing techniques based either on diffractive optics or the reflection of neutrons from surfaces that are coated with supermirror, by using multi-beam set-ups, and of course by the compression of phase space.
Within the JRA3-collaboration, we have investigated all these topics within four tasks.

Results and Applications:
Two types of multi-beam devices have been developed:
• The first, using a multi-beam collimator was manufactured, tested and implemented on the TPA spectrometer at LLB providing flux gains of more than one order of magnitude.
• The second type, MSANS, enables the superposition of thousands of high-resolution mini-SANS cameras. The maximum resolution obtained was corresponding to a length scale of more than 17 μm. Multi-beam set-ups will be used for high-resolution studies in the fields of soft matter, magnetism, and materials science.

Elliptic guides have been developed for the transport of neutrons. First prototypes demonstrate that the expected flux gains of more than a factor of five can be realised. An elliptic neutron guide with a length of 90 m was recently installed at the HRPD diffractometer at ISIS and it performs as specified. Recent neutron scattering experiments with thermal neutrons (PUMA at FRM II) demonstrated the possibility of measuring excitations in samples as small as 1 mm3 ( mg) opening the way of performing inelastic neutron scattering under extreme conditions.

In order to realise large gains in intensity, introducing intermediate layers in artificial multilayers has improved the quality of the coatings. E.g. making the interfaces more diffuse allows for decreasing the roughness and reducing the contribution of higher order reflections. A monochromator with diffuse interfaces is already in use at the neutron reflectometer NARZISS at SINQ and may be installed at other beam lines in the near future.

Significant intensity gains can be realized by accelerating ultra cold neutrons to higher energy by using the Doppler effect. The concept for experiments planned for April 2008 at the ILL have been worked out with the help of a company being specialised in spin-testing devices. First centrifugal tests and characterisations with intercalated graphite have been performed. It is planned using phase space transformation at future UCN-sources to improve the neutron flux for scattering experiments.



Involvement of Partners and number of meetings:
The research within JRA3 has been performed in collaboration with 6 partners from 6 institutions and was observed by 2 institutions.

The work has been discussed during the occasion of six meetings, which were also attended by scientists from non-participating institutions.


Coordinator: Peter Böni