Methods for Determining the Thickness and Elemental Composition of Thin Layers Irradiated by an Ion Beam in Measuring Nuclear Reaction Cross-Sections

VITA, a neutron accelerator based on an accelerating tandem with vacuum isolation, has been created and is now operated at Budker Institute of Nuclear Physics. VITA includes a tandem electrostatic particle accelerator with a unique design (accelerator tandem with vacuum insulation) intended for generating a monochromatic proton or deuteron beam with an energy of up to 2.3 MeV and the current up to 10 mA. The facility is equipped with γ, α, and neutron spectrometers and dosimeters. The accelerator is used for the development of boron neutron-capture therapy of malignant tumors, radiation testing of advanced materials, and more recently for measuring cross-sections of nuclear reactions. Reliable determination of the linear thickness of atomic nuclei, interacting with a charged particle beam and impurities and affecting the charged particle braking rate, is of uttermost importance for measuring cross sections of nuclear reactions. The difficulty in determining these parameters may explain the significant variation in the data on cross-sections of nuclear reactions provided by various groups of researchers. The study presents the results of the measurements of cross-sections of some nuclear reactions. Attention is focused on the description of the methods used to measure the thickness and elemental composition of thin investigated layers irradiated by a proton or deuteron beam. The applicability of these methods and their accuracy are discussed; the results obtained are compared. Proposals for the development of the diagnostic for further measurements of cross-sections of nuclear reactions are discussed.