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Proceedings Paper

Investigation of excitation and ionization excitation of He following electron and proton impact using EUV polarimetry
Author(s): Hocine Merabet; Annette Siems; Reinhard F. Bruch; Jonathan Hanni; Matthew Bailey; Hsiang-Chi Tseng; Chii-Dong Lin; Antonio Gomes Trigueiros
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Paper Abstract

A detailed investigation of excitation of He (1s2) 1S to He (1snp) 1P degree(s) (n equals 2 - 5) states and ionization-excitation of He (1s2) 1S to He (2p) 2P degree(s) and He (3p) 2P degree(s) states in e- + He and H+ + He collision systems is presented for a wide range of projectile velocities (2.2 a.u. < v < 6.9 a.u.). Specifically new experimental data are presented on measurements of the degree of linear polarization for excitation and excitation-ionization of He following proton impact in the extreme ultraviolet (EUV) wavelengths. These measurements have been performed using a characterized molybdenum/silicon multilayer mirror polarimeter (MLM) whose polarization characteristics have been optimized for EUV emission of He and He+. Furthermore, the proton experimental results are compared with theoretical polarization data using the first Born approximation and recent atomic orbital close coupling (AOCC) calculations for the excitation process. A comprehensive comparison of experimental data for negatively and positively charged projectiles at equal impact velocities is also given in order to elucidate differences in the collision mechanisms of two electron targets. It is important to note that these results are relevant for astrophysical diagnostics such as solar flares.

Paper Details

Date Published: 18 December 2000
PDF: 12 pages
Proc. SPIE 4139, Instrumentation for UV/EUV Astronomy and Solar Missions, (18 December 2000); doi: 10.1117/12.410547
Show Author Affiliations
Hocine Merabet, Univ. of Nevada/Reno (United States)
Annette Siems, Univ. Estadual de Campinas (Brazil)
Reinhard F. Bruch, Univ. of Nevada/Reno (United States)
Jonathan Hanni, Univ. of Nevada/Reno (United States)
Matthew Bailey, Desert Research Institute (United States)
Hsiang-Chi Tseng, Chung Yuan Christian Univ. (Taiwan)
Chii-Dong Lin, Kansas State Univ. (United States)
Antonio Gomes Trigueiros, Univ. Estadual de Campinas (Brazil)

Published in SPIE Proceedings Vol. 4139:
Instrumentation for UV/EUV Astronomy and Solar Missions
Silvano Fineschi; Clarence M. Korendyke; Oswald H. W. Siegmund; Bruce E. Woodgate, Editor(s)

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