The creation of defects in 8.7MeV C5-cluster bombarded crystals was studied at doses ranging from 2 x 1010 to 1013/cm2, and was compared with the effect of single energetic C ions. It was found that there was an enhancement of primary defect creation (F-centers) and aggregation (F2-centers) in a near-surface region with a thickness of about 0.3. This corresponded to an energy, per C atom of the incident cluster, which decreased from 1.74MeV at impact, to 1.3MeV. In this region, the C atoms of a cluster were confined to a track with a radius of about 100nm. This was comparable to that of a single C ion track. This led to a very high locally deposited energy density, and was directly responsible for the enhanced defect production which was observed.

A.Perez, M.Doebeli, H.A.Synal: Nuclear Instruments and Methods in Physics Research B, 1996, 116[1-4], 13-7