Failure of Bragg’s rule for a mixture of nonreacting gases
- 1 April 1992
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review A
- Vol. 45 (7) , R4222-R4224
- https://doi.org/10.1103/physreva.45.r4222
Abstract
We show by calculation that for a mixture of nonreacting gases the electronic stopping cross section at low projectile velocities may deviate from the weighted mean of the single-component values (Bragg’s rule). This departure is significant if the individual cross sections for electron capture and electron loss differ considerably. In this case, mixing not only changes the mean charge state in a nonlinear way, but also speeds up the charge-changing cycle. For stopping of 4-keV hydrogen projectiles in a mixture of helium and hydrogen gas, we find that energy losses due to charge-changing processes differ by a factor of 2 from simple additivity. The stopping cross section will be about 50% larger than the result obtained from Bragg’s rule.Keywords
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