A Magnetic Field Cloak For Charged Particle Beams

TL;DR

This paper presents a magnetic field cloak using high-temperature superconductors and ferromagnetic materials to shield charged particle beams from magnetic interference, enhancing experimental precision without external power.

Contribution

It introduces a novel, passive magnetic shielding device combining superconductors and ferromagnetic shells, capable of over 99% shielding at liquid nitrogen temperatures.

Findings

Achieves over 99% magnetic shielding at 0.45 T

Reduces field distortions by 90% with ferromagnetic shell

Operates without external power, unlike active coils

Abstract

Shielding charged particle beams from transverse magnetic fields is a common challenge for particle accelerators and experiments. We demonstrate that a magnetic field cloak is a viable solution. It allows for the use of dipole magnets in the forward regions of experiments at an Electron Ion Collider (EIC) and other facilities without interfering with the incoming beams. The dipoles can improve the momentum measurements of charged final state particles at angles close to the beam line and therefore increase the physics reach of these experiments. In contrast to other magnetic shielding options (such as active coils), a cloak requires no external powering. We discuss the design parameters, fabrication, and limitations of a magnetic field cloak and demonstrate that cylinders made from 45 layers of YBCO high-temperature superconductor, combined with a ferromagnetic shell made from epoxy and stainless steel powder, shield more than 99% of a transverse magnetic field of up to 0.45 T (95 % shielding at 0.5 T) at liquid nitrogen temperature. The ferromagnetic shell reduces field distortions caused by the superconductor alone by 90% at 0.45 T.