Angular differential cross sections for the excitation of 1¹S helium to the 2¹S and 2¹P states by 25- to 100-keV-proton impact

Authors

T. J. Kvale, University of Missouri-Rolla, Rolla, Missouri
D. G. Seely, University of Missouri-Rolla, Rolla, Missouri
D. M. Blakenship, University of Missouri-Rolla, Rolla, Missouri
E. Redd, University of Missouri-Rolla, Rolla, Missouri
Timothy J. Gay, University of Nebraska - LincolnFollow
M. Kimura, University of Missouri-Rolla, Rolla, Missouri
E. Rille, University of Missouri-Rolla, Rolla, Missouri
J. L. Peacher, University of Missouri-Rolla, Rolla, Missouri
J. T. Park, University of Missouri-Rolla, Rolla, Missouri

Date of this Version

September 1985

Comments

Published in Phys. Rev. A 32, 1369 - 1378 (1985) [Issue 3 – September 1985]. ©1985 The American Physical Society. Used by permission.

Abstract

Angular differential cross sections for the proton-impact excitation of ground-state helium (1¹S) to the 2¹S and 2¹P states have been measured for the first time in the energy range 25 to 100 keV with use of the energy-loss technique. The data indicate that, for very small scattering angles, at 25 keV the 2¹S differential cross section is greater than the 2¹P differential cross section. For impact energies greater than 50 keV, the 2¹P differential cross section clearly dominates over the 21S cross section in the very small scattering angle region. The present data have been numerically summed and integrated to compare with previous absolute experimental measurements on related processes. These are in very good agreement with the present results. An eight-state impact parameter calculation incorporating the electron-capture channel was performed and resulted in the best agreement with the experimentally determined differential cross sections.