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Title: Differential double capture cross sections in p+He collisions

Abstract

We have measured differential double capture cross sections for 15 to 150 keV p+He collisions. We also analyzed differential double to single capture ratios, where we find pronounced peak structures. An explanation of these structures probably requires a quantum-mechanical description of elastic scattering between the projectile and the target nucleus. Strong final-state correlations have a large effect on the magnitude of the double capture cross sections.

Authors:
;  [1];  [2]
  1. Physics Department and Laboratory for Atomic, Molecular, and Optical Research, University of Missouri-Rolla, Rolla, Missouri 65409 (United States)
  2. Faculty of Mechanical Engineering and Automation, Kecskemet College, Kecskemet, Izsaki ut 10, H-6000 (Hungary)
Publication Date:
OSTI Identifier:
20982131
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.75.022717; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ATOMS; CAPTURE; CORRELATIONS; CROSS SECTIONS; ELASTIC SCATTERING; HELIUM; HYDROGEN IONS 1 PLUS; ION-ATOM COLLISIONS; IONIZATION; KEV RANGE; NUCLEI; QUANTUM MECHANICS

Citation Formats

Schulz, M., Brand, J. A., and Vajnai, T. Differential double capture cross sections in p+He collisions. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.022717.
Schulz, M., Brand, J. A., & Vajnai, T. Differential double capture cross sections in p+He collisions. United States. doi:10.1103/PHYSREVA.75.022717.
Schulz, M., Brand, J. A., and Vajnai, T. Thu . "Differential double capture cross sections in p+He collisions". United States. doi:10.1103/PHYSREVA.75.022717.
@article{osti_20982131,
title = {Differential double capture cross sections in p+He collisions},
author = {Schulz, M. and Brand, J. A. and Vajnai, T.},
abstractNote = {We have measured differential double capture cross sections for 15 to 150 keV p+He collisions. We also analyzed differential double to single capture ratios, where we find pronounced peak structures. An explanation of these structures probably requires a quantum-mechanical description of elastic scattering between the projectile and the target nucleus. Strong final-state correlations have a large effect on the magnitude of the double capture cross sections.},
doi = {10.1103/PHYSREVA.75.022717},
journal = {Physical Review. A},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • For 0.25{endash}0.75-MeV He{sup 2+} on He collisions we have measured total state selective double capture cross sections and cross sections differential in projectile scattering angle. For 0.25 MeV we present also state-selective scattering-angle-dependent double-capture cross sections. The projectile energy loss (the final electronic state) as well as the transverse momentum transfer (i.e., the projectile scattering angle) have been obtained by measuring the momentum vector of the recoil ion using cold target recoil ion momenum spectroscopy. The resonant transfer to the ground state is found to be by far the dominant double-capture channel. Capture to nonautoionizing excited states is smaller bymore » about a factor of 7, and results in larger scattering angles than the ground-state double capture. {copyright} {ital 1998} {ital The American Physical Society}« less
  • The observation of double excitation of He by positively and negatively charged particles is a multielectron effect. Although multiple excitation is easier to understand than multiple ionization, only very little data is available for doubly excitation. In this work we report high resolution data for double excitation of He{sup **}, mainly (2s{sup 2}){sup 1}S and (2pnp) {sup 1}D and (2snp){sup 1}P{sup 0} states which decay predominantly by autoionization. The autoionization electrons have been detected in the direction of the incoming beam. Second order scattering amplitudes in Z{sub p}, the projectile charge are considered to be important for the (2s{sup 2}){supmore » 1}S and (2pnp){sup 1}D states. The resonance profiles embedded in the continuum background have been parametrized and double differential electron emission cross sections are given as a function of the velocity and projectile charge Z{sub p}.« less
  • Double differential cross sections of doubly excited autoionizing (2p{sup 2}){sup 1}D and (2s2p){sup 1}P states due to 150 eV-1 keV electron, 100 keV-1.5 MeV H{sup +}, 400 KeV-1.6 MeV He{sup +} and He{sup ++} impact on He were measured at zero degree observation angle. Two electrostatic spectrometers were used in tandem where the first analyzer separates the emitted electrons from the incident projectile beam and the second analyzer provides high resolution performance. The projectile beam was tightly collimated and then traversed a 9 mm long gas cell containing 20 mT He gas. All measurements have been performed under single collisionmore » conditions. Strong interference effects between resonance lines and direct ionization continuum are evident in the observed spectra in particular for slower positive projectile ions due to strong Coulomb Interaction in the Final States (CIFS). Our double differential cross sections have been absolutely calibrated using the theoretical and semiempirical single ionization data given by Kim and Rudd. The experimental results are compared with theoretical calculations including three CFIS.« less
  • Energy-gain spectra for single-electron capture by O/sup 2+/ ions colliding with He have been measured at laboratory energies between 60 and 200 eV, and scattering angles between 0/sup 0/ and 4/sup 0/. The spectra indicate that the predominant exit channel is the (2p/sup 3/ /sup 2/P) excited state of O/sup +/. Differential cross sections for capture into the (/sup 2/P) state were also measured. The data show an oscillatory structure. The measurements are in qualitative agreement with recent theoretical calculations based on a full quantum-mechanical description.
  • Charge-exchange differential cross sections are calculated by the second Born approximations without a recourse to any further approximation. The exact second Born approximation cross sections show satisfactory agreement with the experimental data for proton-helium collisions at all the energies of 2.82, 5.42, and 7.4 MeV while they are considerably smaller than the existing experimental cross sections in the Thomas peak region for proton-hydrogen collisions at 2.8 MeV. Discussions are given on how to choose the interactions for two-electron systems in order to satisfy the boundary condition of neutral-atom collisions.