MeV gold irradiation induced damage in alpha-quartz: Competition between nuclear and electronic stopping

Damage creation in crystalline alpha -quartz by irradiation is studied usin g gold ions of energies between 0.5 and 10 MeV. For all ions, the total sto pping power (dE/dx)(tot) has a value of about 4.5 keV/nm, whereas the contr ibution of the electronic stopping power ranges from 0.93 keV/nm at 0.5 MeV to 3.6 keV/nm at 10 MeV. This variation allows us to test which role the n uclear acid the electronic collisions plays for the damage processes. The k inetic of the ion induced damage was determined by channeling RES and the v olume increase by profilometry. Single ion impacts create damage when elect ronic stopping dominates, while several impacts are necessary to achieve da mage in the nuclear stopping regime. A detailed analysis allows us to deduc e the damage cross-sections of the two processes. The electronic stopping p ower of damage creation appears above an electronic dE/dx threshold of 1.4 +/- 0.3 keV/nm. (C) 2001 Elsevier Science B.V. All rights reserved.