Abstract
Monte Carlo shower simulations are essential for understanding and predicting the consequences of beam losses in high-energy proton and ion colliders. Shower simulations are routinely used at CERN for estimating the beam-induced energy deposition, radiation damage, and radioactivity in the Large Hadron Collider (LHC). Comparing these shower simulations against beam loss measurements is an important prerequisite for assessing the predictive ability of model calculations. This paper validates fluka simulation predictions of beam loss monitor (BLM) signals against BLM measurements from proton fills at 3.5 and 4 TeV and Pb20882+ ion fills at 1.38A TeV. The paper addresses typical loss scenarios and loss mechanisms encountered in LHC operation, including proton collisions with dust particles liberated into the beams, halo impact on collimators in the betatron cleaning insertion, proton-proton collisions in the interaction points, and dispersive losses due to bound-free pair production in heavy ion collisions. Model predictions and measured signals generally match within a few tens of percent, although systematic differences were found to be as high as a factor of 3 for some regions and source terms.10 MoreReceived 18 March 2019DOI:https://doi.org/10.1103/PhysRevAccelBeams.22.071003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeam lossParticle phenomenaPhysical SystemsHadron collidersMachine protectionTechniquesMonte Carlo methodsAccelerators & Beams
Highlights
During its first physics run, the Large Hadron Collider (LHC) [1] at CERN successfully stored and collided 3.5 and 4 TeV proton beams as well as 208Pb82þ beams with the same magnetic rigidity [2,3]
A phenomenon frequently observed in the LHC is collisions with microscopic dust particles falling into the stored beams [8,9,10,11,12,13,14,15]
Beam losses and the resulting showers adversely affect collider operation, experiments, equipment, and personnel in several ways. They can lead to magnet quenches, i.e., the sudden loss of superconductivity [21]; they contribute to the heat load to the cryogenic system [22,23]; they cause long-term radiation damage and aging of equipment components [22,23,24,25]; they lead to the production of radioactive isotopes and are a concern for radiation protection [26]; they give rise to background in experiments [27]; and they can induce single-event effects in equipment electronics [28]
Summary
University of Liverpool, Liverpool L69 3BX, United Kingdom and European Organization for Nuclear Research (CERN), Esplanade des Particules 1, 1211 Geneva, Switzerland (Received 18 March 2019; published 11 July 2019). Monte Carlo shower simulations are essential for understanding and predicting the consequences of beam losses in high-energy proton and ion colliders. Shower simulations are routinely used at CERN for estimating the beam-induced energy deposition, radiation damage, and radioactivity in the Large Hadron Collider (LHC). Comparing these shower simulations against beam loss measurements is an important prerequisite for assessing the predictive ability of model calculations. This paper validates FLUKA simulation predictions of beam loss monitor (BLM) signals against BLM measurements from proton fills at 3.5 and 4 TeV and 208Pb82þ ion fills at 1.38A TeV. Model predictions and measured signals generally match within a few tens of percent, systematic differences were found to be as high as a factor of 3 for some regions and source terms
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