Transparent Spin Method for Spin Control of Hadron Beams in Colliders

Abstract: We present a concept for control of the ion polarization, called a transparent spin method. The spin transparency is achieved by designing such a synchrotron structure that the net spin rotation angle in one particle turn is zero. The polarization direction of any ions including deuterons can be efficiently controlled using weak quasi-static fields. These fields allow for dynamic adjustment of the polarization direction during an experiment. The main features of the Transparent Spin method are illustrated in a figure-8 collider. The results are relevant to the Electron-Ion Collider considered in the US, the ion-ion collider NICA constructed in Russia, and a polarized Electron-ion collider planned in China.