EAS Publications Series

The Third European Summer School on Experimental Nuclear Astrophysics
M. Busso, R.G. Pizzone, C. Rolfs, C. Spitaleri and A. Tumino (eds)
EAS Publications Series, 27 (2007) 143-151
DOI: 10.1051/eas:2007149

Electron Screening

F. Raiola

Experimentalphysik III Universitätsstr. 150 NB3/174, 44801 Bochum, Germany

(Published online: 27 September 2007)

Abstract
Understanding the electron screening effect in the laboratory is critical for a correct interpretation of low-energy nuclear reactions in stars. The theory of electron screening in a stellar plasma is still based on the physics model introduced in 1954 by Salpeter, although the mathematical treatments have been improved significatly in the meantime. Extensive studies of the electron screening effect in different nuclear reactions have shown always the same discrepancy, i.e. the experimental $U_{\rm e}\gg$ adiabatic $U_{\rm e}$ . In the recent years extensive studies of the elctron screening effect in deuterated metals (54 metals and 4 insulators) and other environments have been carried out in Bochum. Experimental results of anomalous enhancements have been interpreted in terms of the Debye plasma model, applied to quasi-free metallic electrons. Within this model, the deduced number of valence electrons per metallic atom also agrees with the corresponding number from the Hall coefficient. The expected temperature dependence of the screening potential has been verified together with the expected $Z_{\rm t}$ scaling (with the metallic host) of the Debye radius.