The influence of the spin-flip transitions on the photon spectrum from   ultra-relatiovistic electrons in the field of a crystal
  We investigate the influence of the spin-flip transitions on formation of the spectral distribution of the radiation emitted by tens to hundreds GeV ultrarelativistic electrons incident along crystallographic axis in a thin single crystal. Both the formalism and the numerical data are presented. The calculated spectra for 35 to 243 GeV electrons in W crystal are compared with the dependences obtained experimentally (Kirshenbom K et al 2001 Phys.Rev.Lett 87 054801). 
A.V.Korol, A.V.Solov'yov and W.Greiner