Problems of the dose rate dependence of the defect production by ion beam i
rradiation are addressed. Damage accumulation effects are studied for seque
ntial and overlapping cascades induced by 1 keV recoils in silicon crystals
. The defect generation and evolution is simulated by a molecular dynamics
method using the Stillinger-Weber three body potential. It is shown that th
e damage produced by temporally and spatially overlapping cascades at room
temperature can be both smaller and larger than the total damage induced by
the individual recoils each starting in perfect crystalline silicon. The d
ifferent damage levels are related to the characteristics of the defect str
ucture shortly before and after initiating the subsequent cascades. (C) 200
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