Contribution of the electron–phonon interaction to Lindhard energy partition at low energy in Ge and Si detectors for astroparticle physics applications

• Correction to Lindhard curves of energy partition for low energy selfrecoils based on the exchange of energy during transient thermal processes between electronic and atomic subsystems.
• The correction is evaluated for Ge and Si selfrecoils and could improve the present limits of signals to be used in detection.
• Low and high temperature limits are calculated for the correction.
• A detailed and exhaustive analysis of some properties of Ge and Si, related to transient thermal effects, is performed.

The influence of the transient thermal effects on the partition of the energy of selfrecoils in germanium and silicon into energy eventually given to electrons and to atomic recoils respectively is studied. The transient effects are treated in the frame of the thermal spike model, which considers the electronic and atomic subsystems coupled through the electron–phonon interaction. For low energies of selfrecoils, we show that the corrections to the energy partition curves due to the energy exchange during the transient processes modify the Lindhard predictions. These effects depend on the initial temperature of the target material, as the energies exchanged between electronic and lattice subsystems have different signs for temperatures lower and higher than about 15 K. Many of the experimental data reported in the literature support the model.