Critical points in heavy ion irradiated untwinned YBa2Cu3O7-delta crystals

The critical points in untwinned YBa2Cu3O7-delta crystals with dilute colum nar defects an investigated. We find a convergence of a first order vortex melting line with an irreversibility line associated with the onset of the Bose glass critical regime at the lower critical point. In addition, we fin d that columnar defects raise the upper critical point, implying that vorte x line meandering is a basic feature controlling its position.