Notes on orbit and spin tracking in an electrostatic storage ring

Abstract

Two documents have recently been posted on the arXiv describing a numerical integration algorithm: "symplectic orbit/spin tracking code for all-electric storage rings" [1] and some computational results therefrom [2]. This note comments critically on some of the claims in [1] and [2]. In particular, it is not clear that the orbit tracking algorithm described in [1] is really symplectic. Specifically, for electrostatic beamline elements, the so-called "zero length elements," which are treated as position dependent kicks in the formalism in [1], are in fact {\em not} symplectic.