Abstract:
Neutrons can be an instrument or an object in many fields of research. Major efforts
all over the world are devoted to improving the intensity of neutron sources and the efficiency of
neutron delivery for experimental installations. In this context, neutron reflectors play a key role
because they allow significant improvement of both economy and efficiency. For slow neutrons,
Detonation NanoDiamond (DND) powders provide exceptionally good reflecting performance due
to the combination of enhanced coherent scattering and low neutron absorption. The enhancement
is at maximum when the nanoparticle diameter is close to the neutron wavelength. Therefore, the
mean nanoparticle diameter and the diameter distribution are important. In addition, DNDs show
clustering, which increases their effective diameters. Here, we report on how breaking agglomerates
affects clustering of DNDs and the overall reflector performance. We characterize DNDs using
small-angle neutron scattering, X-ray diffraction, scanning and transmission electron microscopy,
neutron activation analysis, dynamical light scattering, infra-red light spectroscopy, and others.
Based on the results of these tests, we discuss the calculated size distribution of DNDs, the absolute
cross-section of neutron scattering, the neutron albedo, and the neutron intensity gain for neutron
traps with DND walls.
