Investigation of submicroscopic structures by very-slow-neutron transmission experiments

A differential time-of-flight spectrometer of very slow neutrons

“…The transmission of slow neutrons through inhomogeneous media was investigated earlier in [18]. It was shown that, based on the transmission as a function of the neutron wave length, one can deduce characteristic parameters of inhomogeneities, in particular their size and density.…”

“…These formulas were used to interpret measurements of the total and differential cross sections for scattering from inhomogeneous samples (see also [18,19,20]). It has been determined in our work that, in some cases, one of the correlation functions (a Gaussian or exponential function) provides better agreement with the experimental data, but, in other cases, the difference in χ 2 for these two models is inessential: both models represent experimental data well.…”

Ultra-cold neutrons

“…Measurements o n an aluminium-zinc alloy show clearly the appearance of inhomogeneities after precipitation and the size and density of the inhomogeneities determined in this way agree with earlier results from x-ray scattering. Lengsfeld and Steyerl (1977) have measured the scattering on a colloidal suspension of Si02 spheres with known diameter (130-140,k) and thus demonstrated the accuracy of the method. The domain pattern in a ferromagnetic material can also be considered as an inhomogeneous structure for scattering neutrons by means of the magnetic interaction (equation (2.11)).…”

Giant Absorption Cross Section of Ultracold Neutrons in Gadolinium

“…In all cases the 1͞y behavior has been verified, and it was observed that inhomogeneous substances cause additional contributions to the total cross section [5]. The largest measured cross section was 30 kb.…”

“…From optimal fit procedures to the velocity-dependent transmission curves an overall 1͞y cross section can be obtained [Eq. (5)] where the related a values for the solvent and the solvent with the Gd absorber have to be compared. This gives a rather large uncertainty at the higher velocity range where the resolution becomes rather poor Dt͞t ϳ 0.5 and at the low velocity range due to low intensity.…”