Crystal Collimation Cleaning Measurements with 6.5 TeV protons in the LHC

TL;DR

This paper reports on measurements of beam halo cleaning efficiency in the LHC at 6.5 TeV, evaluating the impact of short bent crystals integrated into the collimation system, and comparing results with theoretical models.

Contribution

It introduces the use of short bent crystals as primary collimators in the LHC and compares their performance to standard collimation schemes at collision energy.

Findings

Crystals improved halo cleaning efficiency compared to standard collimation.

Measured results align with theoretical predictions.

Crystals can be effectively integrated into existing collimation systems.

Abstract

Safe disposal of beam halo is a fundamental requirement of modern superconductive hadron colliders to reduce thermal load on magnets and background to experimental detectors. In the CERN Large Hadron Collider (LHC) a multistage system fully compliant with the needs of the baseline operation was build. At a later stage, two short bent crystals were interleaved to the devices for betatron collimation to investigate efficiency enhancement of the halo disposal when inserting them as primary stages of the collimation hierarchy. Each crystal was mounted on a high--accuracy angular actuator, called goniometer, and installed in the clockwise Beam 1, one for the horizontal and one for the vertical plane. In this paper, measurements of the cleaning performance at collision energy with and without inserting crystals in the standard collimation schemes are discussed; the results are compared to theoretical expectations.