A magnetic field cloak for charged particle beams

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2017-10, Vol.877 (C)
• Main Authors: Capobianco-Hogan, K. G., Cervantes, R., Deshpande, A., Feege, N., Krahulik, T., LaBounty, J., Sekelsky, R., Adhyatman, A., Arrowsmith-Kron, G., Coe, B., Dehmelt, K., Hemmick, T. K., Jeffas, S., LaByer, T., Mahmud, S., Oliveira, A., Quadri, A., Sharma, K., Tishelman-Charny, A.
• Format: Article
• Language: English
• Subjects: Electron Ion Collider; Interaction region; Magnetic field cloaking; Magnetic field shielding; NUCLEAR PHYSICS AND RADIATION PHYSICS; Relativistic Heavy Ion Collider
• ISSN: 0168-9002; 1872-9576

Shielding charged particle beams from transverse magnetic fields is a common challenge for particle accelerators and experiments. In this study, 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. Lastly, the ferromagnetic shell reduces field distortions caused by the superconductor alone by 90% at 0.45 T.