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| TUPMW007 | Impact of Long Range Beam-Beam Effects on Intensity and Luminosity Lifetimes from the 2015 LHC Run | 1422 |
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Funding: Research supported by the High Luminosity LHC project Luminosity is one of the key parameters that determines the performance of colliding beams in the Large Hadron Collider (LHC). Luminosity can therefore be used to quantify the impact of beam-beam interactions on the beam lifetimes and emittances. The High Luminosity Large Hadron Collider (HL-LHC) project aims to reach higher luminosities, approximately a factor of 7 larger than the nominal LHC at peak luminosity without crab cavities. Higher luminosities are achieved by increasing the bunch populations and reducing the transverse beam sizes. This results in stronger beam-beam effects. Here the LHC luminosity and beam intensity decay rates are analysed as a function of reducing beam separation with the aim of characterising the impact of beam-beam effects on the luminosity and beam lifetime. The analysis and results are discussed with possible application to the HL-LHC upgrade. |
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| TUPMW008 | Evolution of the Beam Parameters during Luminosity Production in the Future Circular Hadron Collider | 1426 |
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| The evolution of the beam parameters during luminosity production in the Future Circular Hadron Collider (FCC-hh) is described based on basic models of the effect of synchrotron radiations, intra-beam scattering, luminosity burn-off and beam-beam limitations, allowing for an estimation of the luminosity performance in different running scenarios. It is shown that a large variations of the beam parameters is expected during a cycle. Potential operational schemes adapting to these variations are considered. | ||
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| TUPMW009 | Simulation of Head-on Beam-Beam Limitations in Future High Energy Colliders | 1430 |
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| The Future Circular Hadron Collider (FCC-hh) project calls for studies in a new regime of beam-beam interactions. While the emittance damping due to synchrotron radiation is still slower than in past or existing lepton colliders, it is significantly larger than in other hadron colliders. The slow reduction of the emittance is profitable for higher luminosity in term of transverse beam size at the interaction points and also to mitigate long-range beam-beam effects, potentially allowing for a reduction of the crossing angle between the beams during the operation. In such conditions, the strength of head-on beam-beam interactions increases, potentially limiting the beam brightness. 4D weak-strong and strong-strong simulations are performed in order to assess these limitations. | ||
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| TUPMW011 | Current Status of Instability Threshold Measurements in the LHC at 6.5 TeV | 1434 |
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| Throughout 2015, many measurements of the minimum stabilizing octupole current required to prevent coherent transverse instabilities have been performed. These measurements allow the LHC impedance model at flat top to be verified and give good indicators of future performance and limitations. The results are summarized here, and compared to predictions from the simulation code DELPHI. | ||
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| TUPMW037 | Luminosity Targets for FCC-hh | 1523 |
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Funding: Supported by the European Commission under the Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and under the HORIZON 2020 project EuroCirCol, grant agreement 654305. We discuss the choice of target values for the peak and integrated luminosity of a future high-energy frontier circular hadron collider (FCC-hh). We review the arguments on the physics reach of a hadron collider. Next we show that accelerator constraints will limit the beam current and the turnaround time. Taking these limits into account, we derive an expression for the ultimate integrated luminosity per year, depending on a possible pile-up limit imposed by the physics experiments. We finally benchmark our result against the planned two phases of FCC-hh. |
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| WEPOY030 | First BTF Measurements at the Large Hadron Collider | 3051 |
| SUPSS061 | use link to see paper's listing under its alternate paper code | |
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| During the Run I in 2012, several instabilities have been observed at the Large Hadron Collider (LHC) during the Betatron squeeze. The predictions of instability thresholds are based on the computation of the beam Landau damping by calculating the Stability Diagrams (SD). These instabilities could be explained by a deterioration of the SD due to beam-beam resonance excitation which could change the particle distributions. Beam Transfer Functions (BTF) provide a measurement of the Stability Diagram. The BTFs are sensitive to the particle detuning with amplitude as well as to the particle distributions therefore they represent a powerful tool to understand experimentally the stability of beams during the LHC operational cycle. First BTF measurements at the LHC are presented for different machine configurations and settings and compared to predictions. | ||
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