  Both nonresonant and resonance reaction data are subject to laboratory
electron screening effects. For nonresonant reactions, such effects are well
documented and the measured cross sections can be corrected to find the
unscreened ones. Frequently, the procedure and expression to calculate
laboratory electron screening factors for nonresonant reactions are also
applied to isolated narrow resonances, without much theoretical support or
experimental evidence. A simple model is applied to estimate electron screening
factors, lengths, and potentials for narrow resonances. The corrections to the
measured data result in an enhancement of the unscreened resonance strengths by
less than 0.2%, contrary to published narrow-resonance screening correction
factors, which predict a reduction of the unscreened strengths by up to 25%.
Unless it can be proven otherwise, it is recommended that measured strengths of
isolated narrow resonances not be corrected for laboratory electron screening.
The prospects of investigating laboratory electron screening effects by
measuring almost negligible differences in resonance strengths are not
promising. Instead, the difference of the resonance energy for the unscreened
and screened situation may be measurable. As an example, the case of the E_cm =
956-keV resonance in the 27Al(p,gamma)28Si reaction is discussed. It is also
demonstrated that the claim of a previously reported detection of a resonance
near 800 keV in the 176Lu(p,n)176}Hf reaction is incorrect.
