Three of the alkali halides, LiF, KBr, and NaCl were examined as integrating detectors for high energy photons and particles. Dosage measurements were based on the number of color centers formed in single crystals under x‐ and cathode‐ray bombardment. Exposures of 20 to 104r (30‐kv x‐rays) were measured photoelectrically and 105to 107r (3 Mev x‐ and cathode rays) were measured optically. The crystals have advantages in measurements where wide range, high absorption, small size, and simplicity are desirable; however, their use is restricted by the length of the bleaching period required between exposures.