Paper | Title | Page |
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MOPMP031 | Operation and Performance of the Cern Large Hadron Collider During Proton Run 2 | 504 |
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Run 2 of the CERN Large Hadron Collider (LHC) was successfully completed on 10th December 2018, achieving largely all goals set in terms of luminosity production. Following the first two-year long shutdown and the re-commissioning in 2015 at 6.5 TeV, the beam performance was increased to reach a peak luminosity of more than twice the design value and a colliding beam time ratio of 50%. This was accomplished thanks to the increased beam brightness from the injector chain, the high machine availability and the performance enhancements made in the LHC for which some methods and tools, foreseen for the High Luminosity LHC (HL-LHC) were tested and deployed operationally. This contribution provides an overview of the operational aspects, main limitations and achievements for the proton Run 2. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP031 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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TUZZPLM1 | Operational Results of LHC Collimator Alignment Using Machine Learning | 1208 |
SUSPFO053 | use link to see paper's listing under its alternate paper code | |
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A complex collimation system is installed in the Large Hadron Collider to protect sensitive equipment from unavoidable beam losses. The collimators are positioned close to the beam in the form of a hierarchy, which is guaranteed by precisely aligning each collimator with a precision of a few tens of micrometers. During past years, collimator alignments were performed semi-automatically*, such that collimation experts had to be present to oversee and control the alignment. In 2018, machine learning was introduced to develop a new fully-automatic alignment tool, which was used for collimator alignments throughout the year. This paper discusses how machine learning was used to automate the alignment, whilst focusing on the operational results obtained when testing the new software in the LHC. Automatically aligning the collimators decreased the alignment time at injection by a factor of three whilst maintaining the accuracy of the results.
*G.Valentino et al., "Semi-automatic beam-based LHC collimator alignment", PRSTAB, no.5, 2012. |
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Slides TUZZPLM1 [6.060 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLM1 | |
About • | paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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WEYYPLM2 | The 2018 Heavy-Ion Run of the LHC | 2258 |
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The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded. | ||
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Slides WEYYPLM2 [10.884 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2 | |
About • | paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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WEYYPLM3 | First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC | 2262 |
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The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper. | ||
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Slides WEYYPLM3 [6.371 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3 | |
About • | paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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THPRB031 | Operational Performance of the Machine Protection Systems of the Large Hadron Collider During Run 2 and Lessons Learnt for the LIU/HL-LHC Era | 3875 |
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The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB031 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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