| Paper | Title | Page |
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| MOPRB048 | Collimation System Studies for the FCC-hh | 669 |
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| The Future Circular Collider (FCC-hh) is being designed as a 100 km ring that should collide 50 TeV proton beams. At 8.3 GJ, its stored beam energy will be a factor 28 higher than what has been achieved in the Large Hadron Collider, which has the highest stored beam energy among the colliders built so far. This puts unprecedented demands on the control of beam losses and collimation, since even a tiny beam loss risks quenching superconducting magnets. We present in this article the design of the FCC-hh collimation system and study the beam cleaning through simulations of tracking, energy deposition, and thermo-mechanical response. We investigate the collimation performance for design beam loss scenarios and potential bottlenecks are highlighted. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB048 | |
| About • | paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPMP037 | Updated High-Energy LHC Design | 524 |
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Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART. We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb3Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPMP038 | Investigation of CLIC 380 GeV Post-Collision Line | 528 |
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| It has been proposed that the Compact Linear Collider (CLIC) be commissioned in stages, starting with a lower-energy, 380 GeV version for the first stage, and concluding with a 3 TeV version for the final stage. In the Conceptual Design Report (CDR) published in 2012, the post-collision line is described for the 3 TeV and 500 GeV stages. However, the post-collision line for the 380 GeV design was not investigated. This work will describe the simulation studies performed in BDSIM for the 380 GeV post-collision line. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP038 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| MOPRB049 | Study of Beam-Gas Interactions at the LHC for the Physics Beyond Colliders Fixed-Target Study | 673 |
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| Among several working groups formed in the framework of Physics Beyond Colliders study, launched at CERN in September 2016, there is one investigating specific fixed-target experiment proposals. Of particular interest is the study of high-density unpolarized or polarized gas target to be installed in the LHCb detector, using storage cells to enhance the target density. This work studies the impact of the interactions of 7 TeV proton beams with such gas targets on the LHC machine in terms of particle losses. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB049 | |
| About • | paper received ※ 17 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019 | |
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| MOPRB058 | Collimation of Partially Stripped Ion Beams in the LHC | 700 |
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| In the scope of the Physics Beyond Colliders studies, the Gamma Factory initiative proposes the use of partially stripped ions as a driver of a new type, high intensity photon source in CERN’s Large Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially stripped 208-Pb-81+ ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low. The worst losses were localised in the dispersion suppressor (DS) of the betatron-cleaning insertion. Analytic arguments and simulations show that the large losses are driven by the stripping of the remaining electron from the Pb nucleus by the primary collimators. The rising dispersion in the DS pushes the resulting off-rigidity, fully-stripped ions into the aperture of the superconducting magnets. In this study the measured loss maps are compared against results from simulations. Different mitigation strategies are outlined, including a dispersion suppressor (DS) collimator, crystal collimation or an orbit bump. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB058 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPRB059 | Collimation of Heavy-Ion Beams in the HE-LHC | 704 |
| SUSPFO111 | use link to see paper's listing under its alternate paper code | |
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| A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (Pb-82-208) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB059 | |
| About • | paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| MOPRB064 | Precision Modelling of Energy Deposition in the LHC using BDSIM | 723 |
| SUSPFO121 | use link to see paper's listing under its alternate paper code | |
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| A detailed model of the Large Hadron Collider (LHC) has been built using Beam Delivery Simulation (BDSIM) for studying beam loss patterns and is presented and discussed in this paper. BDSIM is a program which builds a Geant4 accelerator model from generic components bridging accelerator tracking routines and particle physics to seamlessly simulate the traversal of particles and any subsequent energy deposition in particle accelerators. The LHC model described here has been further refined with additional features to improve the accuracy of the model, including specific component geometries, tunnel geometry, and more. BDSIM has been extended so that more meaningful comparisons with other simulations and data can be made. Firstly, BDSIM can now record losses in the same way that SixTrack does: when a primary exceeds the limits of the aperture it is recorded as a loss. Secondly, by placing beam loss monitors (BLMs) within the BDSIM model and recording the simulated dose and energy deposition, it can be directly compared with real BLM data. These results are presented here and compared with SixTrack and BLM data from a typical fill in 2018. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB064 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| WEPTS054 | Pyg4ometry : A Tool to Create Geometries for Geant4, BDSIM, G4Beamline and FLUKA for Particle Loss and Energy Deposit Studies | 3244 |
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| Studying the energy deposits in accelerator components, mechanical supports, services, ancillary equipment and shielding requires a detailed computer readable description of the component geometry. The creation of geometries is a significant bottleneck in producing complete simulation models and reducing the effort required will provide the ability of non-experts to simulate the effects of beam losses on realistic accelerators. The paper describes a flexible and easy to use Python package to create geometries usable by either Geant4 (and so BDSIM or G4Beamline) or FLUKA either from scratch or by conversion from common engineering formats, such as STEP or IGES created by industry standard CAD/CAM packages. The conversion requires an intermediate conversion to STL or similar triangular or tetrahedral tessellation description. A key capability of pyg4ometry is to mix GDML/STEP/STL geometries and visualisation of the resulting geometry and determine if there are any geometric overlaps. An example conversion of a complex geometry used in Geant4/BDSIM is presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS054 | |
| About • | paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| WEPTS058 | BDSIM: Recent Developments and New Features Beyond V1.0 | 3259 |
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| BDSIM is a program that creates a 3D model of an accelerator from an optical beam line description using a suite of high energy physics software including Geant4, CLHEP and ROOT. In one single simulation the passage of particles can be tracked accurately through an accelerator including the interaction with the accelerator material and subsequent secondary radiation production and transport. BDSIM is regularly used to simulate beam loss and energy deposition as well as machine detector interface studies. In this paper we present the latest developments beyond BDSIM V1.0 added for ongoing studies. For simulation of collimation systems several new additions are described including new element geometry, enhanced sensitivity and output information. The output has been further enhanced with aperture impact information and dose information from scoring meshes. As well as supporting the full suite of Geant4 physics lists, a new user interface is described allowing custom physics lists and user components to be easily included in BDSIM. New undulator, crystal collimator and wire-scanner elements are also described. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS058 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| THPMP034 | Simulating Matter Interactions of Partially Stripped Ions in BDSIM | 3514 |
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| Acceleration and storage of beams of relativistic partially stripped ions is more challenging than in the case of fully stripped ions because the interactions with matter, such as those with residual gas and collimators can strip electrons via ionisation. BDSIM is a code for the simulation of energy deposition and charged particle backgrounds in accelerators that uses the Geant4 physics library. Geant4 includes a broad range of ion elastic and inelastic interactions and allows the definition of partially stripped ion beams. However, no models are currently available to handle in-flight interactions involving the bound electrons. In this paper we present a semi-empirical model of beam ion stripping by material atoms that is implemented in BDSIM as an extension of Geant4’s existing physics processes and is fully integrated into a comprehensive set of matter interactions for partially stripped ions. The stripping cross-section for select cases and results from comprehensive simulations are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP034 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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