| Paper | Title | Page |
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| TUPRO027 | First Beam Background Simulation Studies at IR1 for High Luminosity LHC | 1074 |
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| In the High-Luminosity Large Hadron Collider (HL-LHC) Project, the LHC will be significantly upgraded to attain a peak luminosity of up to 8.5 × 1034 cm-2s-1, thus almost an order of magnitude higher compared to the nominal machine configuration in ATLAS at IP1 and CMS at IP5. In the view of a successful machine setup as well as a successful physics programme, beam induced background studies at IP1 were performed to investigate sources of particle fluxes to the experimental area. In particular as a start of the study, two sources forming the major contributions were simulated in detail: the first one considers inelastic interactions from beam particles hitting tertiary collimators, the second one from beam interactions with residual gas-molecules in the vacuum pipe close by the experiment, referred to as beam-halo and local beam-gas, respectively. We will present these first HL-LHC background studies based on SixTrack and FLUKA simulations, highlighting the simulation setup for the design case in the HL-LHC scenario. Results of particle spectra entering the ATLAS detector region are presented for the latest study version of HL-LHC machine layout (2013). | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO027 | |
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| WEPME037 | Monte Carlo Simulations of Synchrotron Radiation and Vacuum Performance of the Max IV Light Source | 2344 |
| SUSPSNE101 | use link to see paper's listing under its alternate paper code | |
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| In the MAX IV light-source in Lund, Sweden, the intense synchrotron radiation (SR) distributed along the ring generates important thermal and vacuum effects. By means of a Monte Carlo simulation package, which is currently developed at CERN, both thermal and vacuum effects are quantitatively analysed, in particular near the crotch absorbers and the surrounding NEG-coated vacuum chambers. Using SynRad+, the beam trajectory of the upstream bending magnet is calculated; SR photons are generated and traced through the geometry until their absorption. This allows an analysis of the incident power density on the absorber, and to calculate the photon induced outgassing. The results are imported to Molflow+, a Monte Carlo vacuum simulator that works in the molecular flow regime, and the pressure in the vacuum system and the saturation length of the NEG coating are determined using iterations. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME037 | |
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| WEPME038 | Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+ | 2348 |
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| The Test-Particle Monte Carlo code Molflow+ is getting more and more attention from the scientific community needing detailed 3D calculations of vacuum in the molecular flow regime mainly, but not limited to, the particle accelerator field. Substantial changes, bug fixes, geometry-editing and modelling features, and computational speed improvements have been made to the code in the last couple of years. This paper will outline many of these new features, and show examples of applications to the design and analysis of vacuum systems at CERN and elsewhere. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME038 | |
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| WEPME039 | Leak Propagation Dynamics for the HIE-ISOLDE Superconducting Linac | 2351 |
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| In order to cope with space limitations of existing infrastructure, the cryomodules of the HIE-Isolde superconducting linac feature a common insulation and beam vacuum, imposing the severe cleanliness standard of RF cavities to the whole cryostat. Protection of the linac vacuum against air-inrush from the three experimental stations through the HEBT lines relies on fast valves, triggered by fast cold cathode gauges. To evaluate the leak propagation velocity as a function of leak size and geometry of the lines, a computational and experimental investigation is being carried out at CERN. A 28 m long tube is equipped with strain gauges installed on thin-walled flanges, as well as fast reacting glow discharge and cold-cathode gauges. A leak is opened by the effect of a cutting pendulum, equipped with an accelerometer for data acquisition triggering, on a thin aluminium window followed by a calibrated orifice. The air inrush dynamics is simulated by Test-Particle Monte Carlo in the molecular regime and by Finite Elements fluid dynamics in the viscous regime. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME039 | |
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| WEPME048 | Preliminary Design of the HiLumi-LHC Triplet Area Beam Screen | 2378 |
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The so-called beam screen (BS) is a proven solution for intercepting the thermal loads caused by the circulating beams in the cryogenically-cooled sections of the LHC and minimizing dynamic vacuum effects. The new triplet area foreseen for the HiLumi-LHC machine upgrade has the additional feature of needing internal tungsten shields to reduce the amount of collision debris which is deflected by the high-gradient triplet magnets towards the superconducting magnets' cold masses and coils. The very aggressive optics design, based on large beam separations, calls for a maximum of physical space to remain available to the counter rotating beams in the common BS. This places severe constraints to the fabrication and installation tolerances of the BS itself, in addition to affecting the design and routing of the cryogenic lines in the area. The latest version of the BS design will be shown and discussed, together with future plans for testing materials, fabrication procedures, and installation.
* The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME048 | |
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| WEPME049 | Coupled Simulations of the Synchrotron Radiation and Induced Desorption Pressure Profiles for the HiLumi-LHC Triplet Area and Interaction Points | 2381 |
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The HiLumi-LHC machine upgrade has officially started as an approved LHC project (see dedicated presentations at this conference on the subject). One important feature of the upgrade is the installation of very high-gradient triplet magnets for focusing the beams at the collision points of the two high-luminosity detectors ATLAS and CMS. Other important topics are new superconducting D1 magnets, installation of crab cavities, and re-shuffling of the dispersion suppression area. Based on the current magnetic lattice set-up and beam orbits, a detailed study of the emission of synchrotron radiation (SR) and related photon-induced desorption (PID) has been carried out. A significant amount of SR photons are generated by the two off-axis beams in the common vacuum chamber of the triplet area, about 57 m in length. Ray-tracing Montecarlo codes SYNRAD+ and Molflow+ have been employed in this study. The related PID pressure profiles will be shown, together with simulations using the code VASCO for the analysis of beam losses and background in the detectors, including electron cloud effects.
(*) The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME049 | |
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