Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot

TL;DR

This paper measures and mitigates the beam coupling impedance of a TOTEM Roman Pot using the wire method, demonstrating effective damping of resonances with ferrite plates to meet LHC requirements.

Contribution

It provides the first laboratory measurement of the Roman Pot's impedance and introduces a mitigation technique using ferrite plates.

Findings

Resonances with high Q values were observed in the original configuration.

Ferrite plates effectively damped resonances to meet impedance requirements.

The measurement method validated the impedance mitigation approach.

Abstract

The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance the wire position has been kept constant, and the insertions of the RP were moved asymmetrically. With the original configuration of the RP, resonances with fairly high Q values were observed. In order to mitigate this problem, RF-absorbing ferrite plates were mounted in appropriate locations. As a result, all resonances were sufficiently damped to meet the stringent LHC beam coupling impedance requirements.