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The energy loss of alpha particles in thin layers of various absorbers, including those composed of various materials was investigated.As absorbers, aluminum films with a thickness of 1–10 microns and lavsan films with a thickness of 5–20 microns were used.The radiation sources were standard alpha sources $ {}^{238}Pu$ and ${}^{239}Pu$.
A Gaussian distribution in the calculations approximated the distribution of energy losses near mean energy in the absorbers. The mean energy loss of alpha particle was estimated by Bethe Bloch formulae. The dependence of energy losses on the order of successive layers of aluminum and lavsan in the absorber is obtained if the residual energy of the particles is close to the Bragg peak. This is due to the strong non-linearity of losses near the end of the path of alpha particles and to the different positions of the Bragg peak for various substances. When the sequence of films in the absorber changes, the energy loss changes up to 0.5%. This effect can contribute to the expansion of a single Bragg peak in alpha spectrometry.
