Experiences with permanent magnets at the Fermilab recycler ring

TL;DR

This paper details the design, specifications, and performance of 484 permanent magnets used in the Fermilab recycler ring to achieve high luminosity with cost-effective solutions, emphasizing precise field control and stability.

Contribution

It presents the design criteria, tolerances, and measurement results for permanent magnets in a storage ring, demonstrating their suitability for high-precision accelerator applications.

Findings

Measured magnetic fields within 0.1% of ideal values

Temperature stability better than 0.01% per °C

Harmonics controlled below 0.01%

Abstract

In order to achieve higher luminosities in Run II a separate antiproton storage ring was built in the Main Injector tunnel. To reduce both construction and operations costs permanent magnets were used. This paper discusses the design criterion and specifications, including temperature dependence, longitudinal uniformity, and adjusting of the higher harmonics of the magnets. The design tolerances for a storage ring are more stringent than for a single pass beam line. The difference between the measured and ideal central field for each magnet was held to better than 0.1%. The temperature stability for all magnets was set to better than 0.01% per degree Celsius. Higher order harmonics relative to the central field were set to less than 0.01%. This was done for all 484 permanent magnet that were built.