Abstract
Proposed methods for measuring the electric dipole moment (EDM) of the proton use an intense, polarized proton beam stored in an all-electric storage ring "trap". At the "magic" kinetic energy of 232.792 MeV, proton spins are "frozen", for example always parallel to the instantaneous particle momentum. This paper describes an accelerator simulation code, ETEAPOT, a new component of the Unified Accelerator Libraries (UAL), to be used for long term tracking of particle orbits and spins in electric bend accelerators, in order to simulate EDM storage ring experiments. Though qualitatively much like magnetic rings, the non-constant particle velocity in electric rings give them significantly different properties, especially in weak focusing rings. Like the earlier code TEAPOT (for magnetic ring simulation) this code performs \emph{exact tracking in an idealized (approximate) lattice} rather than the more conventional approach, which is \emph{approximate tracking in a more nearly exact lattice.} The BMT equation describing the evolution of spin vectors through idealized bend elements is also solved exactly---original to this paper. Furthermore the idealization permits the code to be exactly symplectic (with no artificial "symplectification"). Any residual spurious damping or anti-damping is sufficiently small to permit reliable tracking for the long times, such as the 1000 seconds assumed in estimating the achievable EDM precision.
Highlights
The present paper has explained the theoretical basis of the ETEAPOT code
ETEAPOT is a module in the Universal Accelerator Libraries (UAL) code environment [2]
As already mentioned in the abstract, this paper complements the following paper [3], “Electric dipole moment planning with a resurrected BNL Alternating Gradient Synchrotron electron analog ring,” which displays the practical use of the code
Summary
The U.S particle physics community has recently updated its vision of the future and strategy for the decade in a Particle Physics Project Prioritization Panel (P5) Report. This paper is limited to the theoretical orbit and spin dynamical formulation within ETEAPOT, which is a newly developed code within the Universal Accelerator Libraries (UAL) simulation environment [2]. ETEAPOT code with emphasis on details of simulation requirements for the EDM measurement. When numerical values are given, they will usually refer to “magic” conditions, meaning that the beam energy is very close to the magic energy at which spin and momentum precess at the same rate. This is referred to as “frozen spin operation.”. This is referred to as “frozen spin operation.” to prevent invalid approximations from creeping in, the code itself is scrupulously held ignorant of this special condition
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