Color centers beyond the swift ion ranges in LiF crystals

Color centers at a depth up to 3 mm, far beyond the projected ranges of 8–11 MeV/u 12C, 64Ni, 102Ru, 197Au, 208Pb, and 238U ions in LiF crystals, were observed after irradiation with high fluences (1012–1013 ions/cm2). Possible coloration mechanisms (heavy particles, electrons, X- and γ-rays) are analyzed. Experimental results and theoretical estimations allowed presuming different mechanisms of the color center creation beyond the ranges for heavy and light projectiles. Characteristic X-ray emission or energetic primary knocked atoms can be a reason of deep coloration in the case of heavy ions, whereas light projectiles can originate the effect by the products of nuclear reactions (p, He and γ).