Energy Change of a Depolarizing Resonance Due to a Type-3 Siberian Snake

The authors measured the photon beam polarization in the IUCF (Indiana University Cyclotron Facility) Cooler Ring at five energies. They found that the G/sub lambda /=2 imperfection depolarizing resonance occurred about 1.9 MeV below the expected resonance energy of 108.4 MeV. This energy shift could be due to a shift of about +0.0036 in the spin time, nu /sub s/, which is the number of spin rotations in each turn around the ring. It was then demonstrated that this spin tune shift is consistent with the cooler ring containing a partial type-3 Siberian snake, which is apparently caused by the magnets that confine the electron and proton beams in the cooling region.<>