Triplet excitons are used as a sensitive probe for the spatial distribution of paramagnetic defects (exciton sounding). Following α-particle (12-30 MeV) bombardment of an anthracene crystal, a remarkably long tail (supertail) of paramagnetic defects (free radicals) was found, extending into the crystal for a distance of about six times that of the Bragg peak. Evidence is presented that of all possible mechanisms for this supertail, only recoil protons can account quantitatively for the observed spatial distribution. A model calculation indicates that the proton-induced radical yield is about five times that for α particles. The limitations of this model are discussed.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging