Electron paramagnetic resonance data on the defect R1 in

This letter is a comment on some of the conclusions reached by Lea-Wilson and Lomer (1996, Phil. Mag. A, 74, 685) in their discussion of data about the R1 EPR centre formed by radiation damage. In contrast to them, we argue that there is no alternative to account for the details of the EPR spectrum to R1 being a bound pair of nearest neighbouring 100 -split interstitials. We suggest that there are alternative explanations of the other characteristics of the R1 defect which are consistent with this model. This indicates that the R1 is formed by the association of pairs of mobile interstitials, themselves primary radiation products, and that it is not associated with any other defect.