'Two-level', Stokes, and anti-Stokes pumping of a nuclear gamma laser withanisotropic hidden inversion

Recoil in radiative gamma transitions leads to a discrete line spectrum of absorption and emission resonances in an ensemble of free nuclei. This open s up the possibility of efficient pumping of such nuclei and of hidden inve rsion in an nonstandard 'optical' scheme without participation of the third auxiliary level, as well as in Stokes and anti-Stokes schemes. Quantitativ e estimates are given for several nuclides.