Observation of resonance enhanced neutron standing waves through (n, alpha) reaction

The neutron resonances in the (LiF)-Li-6(200 Angstrom)/Ti(2000 Angstrom) /C u(1000 Angstrom)/glass layered structure have been observed simultaneously by neutron reflectivity and Li-6(n, alpha) H-3 nuclear reaction, A ionizati on chamber was used to register the alpha and triton particles emitted afte r the neutron capture in Li-6 nuclei. The observation of the neutron densit y resonant character in the spacer needs a neutron absorber layer which. fo r the present experiment, was the cap layer itself. For definite wavelength s one looks for minima on the reflectivity curve which corresponds to maxim a on the cc-spectra and H-3-spectra. The charged particle normalized intens ity reflects the resonant behavior of neutron density in the cap layer Li-6 which is st result of the realization of the resonances in the spacer laye r (Ti). The decreasing of the enhancement factor with the increasing of the resonance order is directly seen on both registration channels. Fitting of charged particles and neutron data helps significantly in characterizing t he depth profile of the sample and leads to the idea that the Ti spacer lay er could be used as a medium far sensitive investigation. (C) 2000 Elsevier Science B.V. All rights reserved.