Effect of a partial Siberian snake on an ‘‘rf-induced’’ depolarizing resonance

A recent experiment studied the effect of an rf solenoid magnet and a partial Siberian snake on a 120-MeV polarized proton beam. We measured the frequencies of the ``rf-induced''depolarizing resonance for different values of the snake strength; this frequency measurement determined the spin tune ${\ensuremath{\nu}}_{\mathrm{sp}}$, which is the number of spin processions in one turn around the ring. A 4% snake increased the frequency of the rf-induced depolarizing resonance by the predicted 11 kHz and thus shifted the spin tune by the predicted \ensuremath{\Delta}${\ensuremath{\nu}}_{\mathrm{sp}}$=0.006 88\ifmmode\pm\else\textpm\fi{}0.000 04; as expected the 4% snake also tilted the stable spin direction by more than 38\ifmmode^\circ\else\textdegree\fi{} from the vertical.