We plan to improve the design and fabrication technology of the converging honeycomb (HC) collimators to get higher flexibility as to the total length and hexagonal section. Different coatings of the profiles by neutron absorbing materials will be investigated (BNC). Test of the collimator performances (ISI/BNC) and insertion in a SANS instrument BNC will be performed.
We will develop and implement a multibeam technology for increasing the flux on SANS experiments. Recent tests in collaboration between the LLB and BNC have demonstrated that the concept is actually working and provide the expected neutron flux gains. Within this task, the work will consist in designing an actual multibeam solution that can be implemented practically on a SANS spectrometers without compromising its configuration flexibility (varying wavelength, collimation length). The task will benefit from the experience developed at BNC and LLB but we will also use the HC technology developed at INFM for implementing on a multiple beam SANS set-up. This HC technology allows producing highly collimated beams without cross talk.
In parallel (cooperation with R. Gähler, ILL), the technology of multiple holes SANS will be developed and implemented in collaboration between TUM and PSI. It uses the common SANS infrastructure except for the detector, which requires enhanced spatial resolution. The tests and characterisation will be carried out at PSI and FRM-II. A MSANS device will be implemented at the MIRA beam line for very cold neutrons at FRM-II.
For several experiments as strain analysis or neutron activation analysis a neutron lens with a short focal length of several 100 mm would be valuable. We want to explore the possibilities of a solid-state neutron lens, which focuses the neutrons from a neutron guide to a spot. It will be composed of thin Si wafers coated with a reflecting supermirror, which are bent by an appropriate apparatus. This is a joint project of HMI and BNC.

Results
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.

• Report on the improved silicon lens:
(PDF, 0.142 MB )
• Multiple Small Angle Neutron Scattering (MSANS):
(PDF, 0.987 MB)
• Converging Honeycomb Collimators and Fresnel Lenses:
(PDF, 0.366 MB)




Section of an MSANS detector image of a 2 micron period Gd absorption
grating.

Multibeam prototype