Thin polycrystalline Ni films of typically 75 nm thickness evaporated on Si or SiO<Subscript>2</Subscript> substrates were irradiated with 30-900 keV Xe-ions to fluences of 2.5 x 10<Superscript>13</Superscript> - 4 x 10<Superscript>14</Superscript>/cm<Superscript>2</Superscript>. The magnetization of the Ni films was measured using the longitudinal Magneto-Optical Kerr Effect and Vibrating Sample...</superscript></superscript></superscript></subscript>