Provider International Atomic Energy Agency
IAEA CRP F1.20.21 2007-2011
Proposer RNDr. Pavol Mikula, DrSc., ÚJF AV ČR, v.v.i.
Title Improved production and utilization of short pulsed, cold neutrons at low-medium energy spallation neutron sources

Participation on multilateral project with the task: Development and optimization of a curved wide wavelength band monochromator based on strongly cylindrically bent perfect Si-slabs in a sandwich for microfocusing small-angle neutron scattering (mfSANS) device.


SANS is a very powerful and popular technique to study nano-scale structure in a matter. Practically, every neutron facility over the world has at least one or two such instruments, but very often, they are over-subscribed and it is not so easy to obtained a beam time on these machines. The research group from Hokkaido University has been proposed a new and unconventional type of a high resolution SANS instrument called as Minifocusing small-angle neutron scattering instrument (mfSANS) which can have a revolutionary impact on the instrumentation development namely at the medium and lower power neutron sources. Using a compact ellipsoidal mirror as a focusing device and high resolution position sensitive detectors, which have been developed in the last decade, it is possible to construct a very compact and versatile focusing-type SANS instrument. This development of the SANS device would permit to demonstrate an inexpensive instrument which can be designed and realized for operation at different neutron wavelengths. As the instrument can be designed at different wavelengths, then by using e.g. two or three instruments operating at different wavelengths one can substantially enlarge the range of momentum transfer with respect to conventional collimator SANS devices. It also permits one to enlarge the number of highly demanded neutron scattering instruments installed at the medium or low power pulsed or steady state neutron sources in a rather inexpensive way. The mock-up test experiments of the time-of-flight type mfSANS have been carried out at a small pulsed cold-neutron source at Hokkaido University. It is based on a 45 MeV electron linac combined with a high-performance solid-methane cold neutron moderator. In this case an ellipsoidal mirror with 4 m between focusing points is used with Ni coating on it. The actual length of the mirror was 900 mm and it has a cross-section of 1/4 of a circle with radius of around 20 mm. At present, a prototype of mfSANS is installed at the JRR-3 reactor in JAERI Tokai.