SPIN TUNE DECOHERENCE IN MULTIPOLE FIELDS

Abstract

This article analyses possible limitations in the method to search for the electric dipole moment (EDM) using polarized particles in a storage ring [1]. It is well known that for discovery of the electric dipole moment one needs to create such conditions where the particle's spin oscillations can be caused only by the EDM. There is some number of possible methods for EDM search using a storage ring. For instance at present we know the resonant spin build-up method in a magnetostatic ring and “frozen” spin method in a pure or partly electrostatic ring with magic energy. Both methods have common limitations caused by spin decoherence. In a previous article [2] we considered the main reasons leading to incoherent spread of spin tune taking into account only second-order nonlinearity. In this article, we have extended this method to the case for the higher orders, and the reasons of the spin decoherence are classified independently on method.