Perfect crystal grasers

We discuss the advantages obtained in the conditions for γ-ray lasing (grasing) by utilizing a crystalline sample rather than an amorphous needle. We show that, for emitters of multipole M1 or higher, the favored grasing mode will be a Borrmann channel at the largest available Bragg angle. Further, we give necessary conditions on the population inversion density to determine a practical pulsed laser. The same gain factors, and thus the same advantages of crystalline over amorphous samples, occur in the equations describing both steady state and pulsed lasers, as well as superradiators. Finally, we indicate that, for any practical system, the predominant mode of de-excitation will be superradiance, rather than stimulated emission.