Measurements of heavy ion beam losses from collimation

TL;DR

This study measures and simulates heavy ion beam losses from collimation in the LHC, revealing differences from proton losses and validating models of ion beam loss mechanisms.

Contribution

It provides experimental data and simulation comparisons for Pb ion beam losses, improving understanding of collimation efficiency in the LHC.

Findings

Pb ion losses differ from proton losses in location and magnitude.

Simulations accurately predict loss patterns observed in measurements.

Results serve as benchmarks for ion beam loss models.

Abstract

The collimation efficiency for Pb ion beams in the LHC is predicted to be lower than requirements. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements and simulations of loss patterns generated by a prototype LHC collimator in the CERN SPS. Measurements were performed at two different energies and angles of the collimator. We also compare with proton loss maps and find a qualitative difference between Pb ions and protons, with the maximum loss rate observed at different places in the ring. This behavior was predicted by simulations and provides a valuable benchmark of our understanding of ion beam losses caused by collimation.