Energy loss of low energy protons channeling in silicon crystals

Abstract

Experimental energy loss measurements were made for protons of energy 0.5 to 1.6 MeV channeling through 1 μm thick silicon targets along the (110), (111), and (211) axial directions, and the {100}, {110}, {111}, and {211} planar directions. These data have a precision of ±5% and are presented graphically along with an extensive summary of other data in the literature. The new data cover a wider range of channels than has previously been examined with protons and are in agreement with the helium data of Eisen et al. A standard theory of energy loss is summarized and amplified, and straggling is calculated theoretically. Local electron densities for various channels in silicon are extracted from plane and row averaged Thomas Fermi potentials via ▿^2 V = 4 πρ, and are used in the theoretical energy loss and straggling equations. The results agree with the experimental data to within 5%. The need for more precise measurements in order to make a decisive test of the theory is discussed.

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