Thin tristearin deposits as solid hydrogen-rich layers for neutron metrology

Layers of solid material with a relatively high, constant content of hydrogen that is stable over a long period of time are needed for recoil proton telescopes and for precise determination of the cross-section ratio of 235U(n,f)/H(n,n). Thin layers of tristearin, a material that is relatively rich in hydrogen, have been prepared with an areal density of 0.05 up to 0.5 mg cm-2 by evaporation in high vacuum. The surface quality was studied by AFM (atomic force microscopy). The thickness of the layers was estimated by several methods and its homogeneity was determined using an optical profilometer. The hydrogen amount in the deposited layer was estimated by combustion analyses.