The Russians are working on the graser. One B. V. Chirkov has published a theoretical study in the Soviet Journal of Experimental and Theoretical Physics. He thinks a very pure crystal, "pumped" with a powerful source of radiation (such a "hard" X rays), much as a ruby crystal is pumped with high-intensity light in one form of laser, could be stimulated to emit coherent gamma rays—pulses of high-energy radiation perfectly in step.