Bragg-Rule Applicability to Stopping Cross Sections of Gases for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>Particles of Energy 0.3-2.0 MeV

Abstract

The additivity of atomic stopping cross sections, Bragg's rule, is tested for $\ensuremath{\alpha}$ particles in the gaseous compounds ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, N${\mathrm{H}}_{3}$, ${\mathrm{N}}_{2}$O, CO, C${\mathrm{O}}_{2}$, C${\mathrm{H}}_{4}$, ${\mathrm{C}}_{2}$${\mathrm{H}}_{2}$, ${\mathrm{C}}_{2}$${\mathrm{H}}_{4}$, ${\mathrm{C}}_{2}$${\mathrm{H}}_{6}$, ${\mathrm{C}}_{3}$${\mathrm{H}}_{6}$ (propylene), and ${(\mathrm{C}{\mathrm{H}}_{2})}_{3}$ (cyclopropane). Compounds with single and double bonds are found to obey Bragg's rule. Compounds containing triple-bond structure are found to deviate from Bragg's rule by as much as 12.8%, but an empirical triple-bond correction is made to fit all the data of the present experiment. Evidence is seen for a possible physical-state effect.