Reaching record-low<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0032.gif" overflow="scroll"><mml:msup superscriptshift="75%"><mml:mrow><mml:mi>β</mml:mi></mml:mrow><mml:mrow><mml:mo form="prefix">*</mml:mo></mml:mrow></mml:msup></mml:math>at the CERN Large Hadron Collider using a novel scheme of collimator settings and optics

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The Large Hadron Collider (LHC) at CERN is a 7 TeV proton synchrotron, with a design stored energy of 362 MJ per beam. The high-luminosity (HL-LHC) upgrade will increase this to 675 MJ per beam. In order to protect the superconducting magnets and other sensitive equipment from quenches and damage due to beam loss, a multi-level collimation system is needed. Detailed simulations are required to understand where particles scattered by the collimators are lost around the ring in a range of machine configurations. Merlin++ is a simulation framework that has been extended to include detailed scattering physics, in order to predict local particle loss rates around the LHC ring. We compare Merlin++ simulations of losses during the squeeze (the dynamic reduction of the β-function at the interaction points before the beams are put into collision) with loss maps recorded during beam squeezes for Run 1 and 2 configurations. The squeeze is particularly important as both collimator positions and quadrupole magnet currents are changed. We can then predict, using Merlin++, the expected losses for the HL-LHC to ensure adequate protection of the machine.

“…This allows a clean loss map for an individual beam and plane to be made. Measured LHC loss maps have been studied previously in [11,15].…”

Section: Loss Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance of the Large Hadron Collider cleaning system during the squeeze: Simulations and measurements

Tygier

Appleby

Bruce

et al. 2019

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“…This is part of the HL-LHC upgrade, where new advanced materials are under consideration as replacement of the present tungsten jaw [10]. The losses on TCTs during an SMPF could also potentially be reduced by rematching the optics to improve the phase advance between MKDs and TCTs [50,51], as it was done for the LHC configuration in 2016 [28].…”

Section: Resultsmentioning

confidence: 99%

Modeling of beam-induced damage of the LHC tertiary collimators

Quaranta

Redaelli

Lechner

et al. 2017

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Modern hadron machines with high beam intensity may suffer from material damage in the case of large beam losses and even beam-intercepting devices, such as collimators, can be harmed. A systematic method to evaluate thresholds of damage owing to the impact of high energy particles is therefore crucial for safe operation and for predicting possible limitations in the overall machine performance. For this, a three-step simulation approach is presented, based on tracking simulations followed by calculations of energy deposited in the impacted material and hydrodynamic simulations to predict the thermomechanical effect of the impact. This approach is applied to metallic collimators at the CERN Large Hadron Collider (LHC), which in standard operation intercept halo protons, but risk to be damaged in the case of extraction kicker malfunction. In particular, tertiary collimators protect the aperture bottlenecks, their settings constrain the reach in β Ã and hence the achievable luminosity at the LHC experiments. Our calculated damage levels provide a very important input on how close to the beam these collimators can be operated without risk of damage. The results of this approach have been used already to push further the performance of the present machine. The risk of damage is even higher in the upgraded high-luminosity LHC with higher beam intensity, for which we quantify existing margins before equipment damage for the proposed baseline settings.

“…SPPC (Super Proton-Proton Collider) is a next-generation proton-proton collider aiming for energy-frontier physics, especially for beyond-Standard Model research. It is the second phase of the CEPC-SPPC project which was proposed by Chinese scientists, and the two colliders use the same tunnel [10]. As a future proton-proton collider, SPPC will collide protons at a center of mass energy of 75 TeV, with circumference of 100 km, a nominal luminosity of 1.01  10 35 cm -2 s -1 per IP.…”

Section: Appendix: Brief Of the Design Features And Mainmentioning

confidence: 99%

Collimation method studies for next-generation hadron colliders

Yang

Zou

Tang

2019

In order to handle extremely-high stored energy in future proton-proton colliders, an extremely high-efficiency collimation system is required for safe operation. At LHC, the major limiting locations in terms of particle losses on superconducting (SC) magnets are the dispersion suppressors (DS) downstream of the transverse collimation insertion. These losses are due to the protons experiencing single diffractive interactions in the primary collimators. How to solve this problem is very important for future proton-proton colliders, such as the FCC-hh and SPPC. In this article, a novel method is proposed, which arranges both the transverse and momentum collimation in the same long straight section. In this way, the momentum collimation system can clean those particles related to the single diffractive effect. The effectiveness of the method has been confirmed by multi-particle simulations. In addition, SC quadrupoles with special designs such as enlarged aperture and good shielding are adopted to enhance the phase advance in the transverse collimation section, so that tertiary collimators can be arranged to clean off the tertiary halo which emerges from the secondary collimators and improve the collimation efficiency. With one more collimation stage in the transverse collimation, the beam losses in both the momentum collimation section and the experimental regions can be largely reduced. Multi-particle simulation results with the MERLIN code confirm the effectiveness of the collimation method. At last, we provide a protection scheme of the SC magnets in the collimation section. The FLUKA simulations show that by adding some special protective collimators in front of the magnets, the maximum power deposition in the SC coils is reduced dramatically, which is proven to be valid for protecting the SC magnets from quenching.