Compensation for Booster Leakage Field in the Duke Storage Ring

TL;DR

This paper presents a novel orbit compensation scheme using fast correctors to mitigate booster leakage field effects in the Duke storage ring, improving beam stability for precision gamma-ray experiments.

Contribution

The paper introduces a new feedforward orbit correction method that effectively compensates booster leakage fields in the storage ring.

Findings

The scheme successfully reduces orbit distortion caused by booster leakage.

Measurement results confirm the effectiveness of the compensation scheme.

The method operates transparently with existing feedback systems.

Abstract

The High Intensity Gamma-ray Source (HIGS) at Duke University is an accelerator-driven Compton gamma-ray source, providing high flux gamma-ray beam from 1 MeV to 100 MeV for photo-nuclear physics research. The HIGS facility operates three accelerators, a linac pre-injector (0.16 GeV), a booster injector (0.16-1.2 GeV), and an electron storage ring (0.24-1.2 GeV). Because of proximity of the booster injector to the storage ring, the magnetic field of the booster dipoles close to the ring can significantly alter the closed orbit in the storage ring being operated in the low energy region. This type of orbit distortion can be a problem for certain precision experiments which demand a high degree of the energy consistency of the gamma-ray beam. This energy consistency can be achieved by maintaining consistent aiming of the gamma-ray beam, therefore, a steady electron beam orbit and angle at the Compton collision point. To overcome the booster leakage field problem, we have developed an orbit compensation scheme. This scheme is developed using two fast orbit correctors and implemented as a feedforward which is operated transparently together with the slow orbit feedback system. In this paper, we will describe the development of this leakage field compensation scheme, and report the measurement results which have demonstrated the effectiveness of the scheme.