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LiF and NaCl crystals were irradiated at 8 K and 300 K with various light and heavy ions ͑C, Ti, Ni, Kr, Sm, Au, Pb, and U͒ of kinetic energy between about 50 and 2600 MeV, providing electronic energy losses from 0.7 to 26.4 keV/nm. A cryostat installed at the beamline allowed in situ absorption spectroscopy and thermostimulated luminescence ͑TSL͒ measurements from 8 K upward. Creation of electron and hole color centers is analyzed as a function of irradiation temperature, fluence, and thermal and optical bleaching. Anion interstitials ͑I and H centers͒ were only observed in crystals irradiated at 8 K. These defects are unstable and disappear in the temperature range 10-100 K. For heavy ions ͑Au, U͒, the F-center accumulation efficiency at low fluences is larger at 8 K than at room temperature. The opposite effect is observed for light ions ͑C, Ti, Ni͒. The results are discussed within the frame of transient heating influencing separation or annealing of point defects. − are charged anion molecules; X int − is a charged anion on an interstitial position; H A1 and H A2 are H centers next to an impurity A 1 and A 2 , respectively; nF is a F-center cluster.

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