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| MOPTY052 | Experimental and Simulation Studies of Hydrodynamic Tunneling of Ultra-Relativistic Protons | 1048 |
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The expected damage due to the release of the full LHC beam energy at a single aperture bottleneck has been studied. These studies have shown that the range of the 7 TeV LHC proton beam is significantly extended compared to that of a single proton due to hydrodynamic tunneling effect. For instance, it was evaluated that the protons and their showers will penetrate up to a length of 25 m in solid carbon compared to a static range of around 3 m. To check the validity of these simulations, beam- target heating experiments using the 440 GeV proton beam generated by the SPS were performed at the HiRadMat test facility at CERN *. Solid copper targets were facially irradiated by the beam and measurements confirmed hydrodynamic tunneling of the protons and their showers. Simulations have been done by running the energy deposition code FLUKA and the 2D hydrodynamic code, BIG2, iteratively. Very good agreement has been found between the simulations and the experimental results ** providing confidence in the validity of the studies for the LHC. This paper presents the simulation studies, the results of a benchmarking experiment, and the detailed target investigations.
* N.A. Tahir et al., Phys. Rev. Special Topics Accel. Beams 15 (2012) 051003. ** R. Schmidt et al., Phys. Plasmas 21 (2014) 080701. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY052 | |
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| MOPTY057 | Feasibility Study of Monitoring the Population of the CERN-LHC Abort Gap with Diamond Based Particle Detectors | 1065 |
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| At the end of a physics fill and in case of a failure, the LHC beams must be extracted and transferred through a 750m long line to the beam dump block. During the rise of the extraction kickers to their full strength a particle-free abort gap, with a length of 3 us in the LHC filling pattern, is required to prevent beam losses that could lead to substantial quenching of magnets, with a risk of damage. Therefore the particle population in the abort gap, which is mainly due to un-bunched beam, is monitored. Above a certain threshold an active cleaning by excitation of betatron oscillations with the transverse feedback system is initiated. This paper describes a novel method of monitoring the abort gap population using diamond particle detectors for detecting the interactions of beam in the abort gap with neon gas, injected in the beam pipe. Two different layouts of the system and the expected interaction and detection rates are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY057 | |
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| MOPTY058 | Response of Polycrystalline Diamond Particle Detectors Measured with a High Intensity Electron Beam | 1069 |
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| Comprehensive understanding of beam losses in the LHC is required to ensure full machine protection and efficient operation. The existing BLM system using ionization chambers is not adequate to resolve losses with a time resolution below some 10 us. Ionization chambers are also not adequate to measure very large transient losses, e.g. beam impacting on collimators. Diamond particle detectors with bunch-by-bunch resolution have therefore been used in LHC to measure fast particle losses with a time resolution down to a level of single bunches. Diamond detectors have also successfully been used for material damage studies in other facilities, e.g. HiRadMat at the CERN-SPS. To fully understand their potential, such detectors were characterized with an electron beam at the BTF in LNF INFN Italy, with bunch intensities from 103 to 109 electrons. The detector response and efficiency has been measured with a 50 Ω and a 1 Ω read-out system. This paper describes the experimental setup and the results of the experiment. In particular, the responses of three samples of 100 um single-crystalline diamond detectors and two samples of 500 um polycrystalline diamond detectors are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY058 | |
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| TUPTY052 | New Method for Validation of Aperture Margins in the LHC Triplet | 2140 |
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Funding: Work supported by COFUND grant PCOFUND-GA-2010-267194 Safety of LHC equipment including superconducting magnets depends not only on the proper functioning of the systems for machine protection, but also on the accurate adjustment of the protective devices such as collimators. In case of a failure of the extraction kicker magnets, which are part of the beam dumping system, it is important to ensure protection of the superconducting triplet magnets from missteered beam. The magnets are located to the right of Interaction Point 5 (IP5) and are protected by one set of collimators in the beam dumping insertion in IR6 and another set close to the triplet magnets. In this paper, a new method for verification of the correct collimator position with respect to the aperture is presented. It comprises the application of an extended orbit bump with identical trajectory as the beam trajectory after a deflection by the beam dump kickers. By further increasing the bump amplitude and successively moving in/out the collimators in the region of interest, the accurate positioning of the collimators can be validated. The effectiveness of the method for LHC IP5 and IP1 and both beams is discussed |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY052 | |
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| TUPTY053 | Roadmap towards High Accelerator Availability for the CERN HL-LHC Era | 2143 |
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| High Luminosity-LHC is the future upgrade of the LHC that aims at delivering an integrated luminosity of 3000 fb-1 over about 10 years of operation, starting from 2025. Significant modifications [1] will be implemented to accelerator systems, including new superconducting magnets, crab cavities, superconducting links, new collimators and absorbers based on advanced materials and design and additional cryo-plants. Due to the limit imposed by the number of simultaneous events at the experiments (pile-up) on peak luminosity, the latter will be levelled to 5*1034 cm-2s−1. The target integrated luminosity can only be achieved with a significant increase of the total available time for beam collisions compared to the 2012 LHC run, despite a beam current that is planned to double the nominal 0.58 A. Therefore one of the key figures of merit to take into account for system upgrades and new designs is their impact on the accelerator availability. In this paper the main factors affecting LHC availability will be discussed and predictions on the impact of future system upgrades on integrated luminosity presented. Requirements in terms of the maximum allowed number of dumps for the main contributing systems to LHC unavailability will be derived. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY053 | |
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| WEPHA016 | Experimental Setups to Determine the Damage Limit of Superconducting Magnets for Instantaneous Beam Losses | 3138 |
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| The damage mechanism of superconducting magnets due to the direct impact of high intensity particle beams is not well understood. Obvious candidates for upper bounds on the damage limit are overheating of insulation, and melting of the conductor. Lower bounds are obtained by the limits of elasticity in the conductor, taking into account dynamic effects (elastic stress waves). The plastic regime in between these two bounds will lead to differential thermal stress between the superconductor and stabilizer, which may lead to a permanent degradation of the magnet. An improved understanding of these mechanisms is required especially in view of the planned increase in brightness of the beams injected into the LHC and of the future High Luminosity-LHC [2] and Future Circular Collider (FCC). In this paper the plans for room temperature damage tests on critical parts of superconducting magnets and the strategy to test their damage levels at 4.3 K in the HiRadMat facility at CERN , using a 440 GeV proton beam generated by the Super Proton Synchrotron (SPS), is presented. Moreover the status of numerical simulations using FLUKA and multi-physics FEM code (ANSYS) to assess the different effect and the irradiation of the proposed experimental setup in preparation of the test is shown. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA016 | |
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| THPF095 | Limits on Failure Scenarios for Crab Cavities in the HL-LHC | 3923 |
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| The High Luminosity (HL) LHC upgrade aims for a tenfold increase in integrated luminosity compared to the nominal LHC, and for operation at a levelled luminosity of 5 1034 cm-2.s-1, which is five times higher than the nominal LHC peak luminosity. Crab Cavities (CCs) are planned to compensate the geometric luminosity loss created by the increased crossing angle by rotating the bunch, allowing quasi head-on collisions at the Interaction Points (IP). The CCs work by creating transverse kicks, and their failure may have short time constants comparable to the reaction time of the Machine Protection System (MPS), producing significant coherent betatron oscillations and fast emittance growth. Simulations of CC failure modes have been carried out with the tracking code SIXTRACK, using the newly added functionality called DYNK, which allows to dynamically change the attributes of the CCs. We describe these simulations and discuss early, preliminary results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF095 | |
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