Crossing Intrinsic Depolarizing Resonances by Varying a Partial Siberian Snake

Abstract

We recently forced a 140 MeV polarized proton beam to cross intrinsic depolarizing resonances by varying a partial Siberian snake's strength for different values of the vertical and horizontal betatron tunes ${\ensuremath{\nu}}_{y}$ and ${\ensuremath{\nu}}_{x}$. A weak second-order intrinsic resonance was observed in the ${\ensuremath{\nu}}_{x}$ sweep; moreover, an unexpected partial spin flip was found in the ${\ensuremath{\nu}}_{y}$ sweep. We also varied the snake ramp time to identify the ${\ensuremath{\nu}}_{y}$ and ${\ensuremath{\nu}}_{x}$ regions where the resonance crossings occurred during the snake variation; in these crossings the polarization partially deviated from Froissart-Stora behavior.