A Spin Tune Model for Spin Coherence Time Optimisation at Storage Rings

Abstract

Electric Dipole Moments (EDMs) are very sensitive probes of physics beyond the Standard Model (SM). The JEDI collaboration aims to measure the EDMs of charged particles making use of polarised beams in a storage ring. Such a precision experiment requires the maximisation of the Spin Coherence Time (SCT). To identify the working conditions that maximise the SCT, the spin tune of the single particles must be tracked with high precision. With this experiment in mind, this paper presents a model that accurately tracks the spin tune in a variety of lattices representing existing storage rings as well as a future class of dedicated storage rings. These lattices differ in the combination of electric and magnetic fields used for particle confinement and the number of sextupole families. Furthermore, the parameters used in the model are shown to be directly accessible from beam diagnostics and sextupole field strengths via linear models. Finally, the study explores the implications of the model on the decoherence of a beam stored in such storage rings. The spin tune model outcomes were verified by comparison to those of the brute force searches of configurations with SCTs of more than 1000 seconds. The result was a deeper mathematical understanding of the phenomenon as well as a method to find the setting which optimises the SCT.

Authors 4

1. Rahul Shankar

   Istituto Nazionale di Fisica Nucleare · University of Ferrara · Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara

   Affiliation as printed

   . Istituto Nazionale di Fisica Nucleare (INFN) , Ferrara , Italy

   . Università degli studi di Ferrara , Ferrara , Italy

2. Anna Piccoli
3. P. Lenisa

   Istituto Nazionale di Fisica Nucleare · University of Ferrara · Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara

   Affiliation as printed

   . Istituto Nazionale di Fisica Nucleare (INFN) , Ferrara , Italy

   . Università degli studi di Ferrara , Ferrara , Italy

4. A. Lehrach Aachen Physikalisches Institut B

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   . Forschungszentrum Jülich , 52425 Jülich , Germany

   . Physikalisches Institut B , RWTH Aachen University Aachen , Germany