| Paper | Title | Page |
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| MOPAB130 | Cross-Calibration of the LHC Transverse Beam-Profile Monitors | 437 |
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| Calibration of a transverse beam profile monitor is of fundamental importance to guarantee the best possible accuracy and reliability of the instrument over time. In LHC the calibration standard for transverse-profile measurements are the wire scanners. Other profile monitors such as beam synchrotron light telescopes and interferometers are calibrated with respect to them. Additional information about single-bunch sizes can be obtained from beam-gas imaging in the LHCb vertex detector, from the transverse convolved beam sizes extracted from luminosity scans at the collision points, and from the evolution of the luminous-region parameters as reconstructed by ATLAS and CMS inner tracker detectors during such scans. For the first time in LHC, a dedicated cross-calibration of all the above-mentioned systems was carried out with beam in 2016. Additionally, dedicated optics measurements were also performed in order to determine with the highest possible accuracy the amplitude function at the interaction points and at the position of the profile monitors. Results of these measurements are presented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB130 | |
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| WEPIK030 | Experimental Validation of the Achromatic Telescopic Squeezing Scheme at the LHC | 2992 |
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The Achromatic Telescopic Squeezing (ATS) [1] scheme offers new techniques to deliver unprecedentedly small beam spot size at the interaction points of the ATLAS and CMS experiments of the LHC, while perfectly controlling the chromatic properties of the corresponding optics (linear and non-linear chromaticities, off-momentum beta-beating, spurious dispersion induced by the crossing bumps). The first series of beam tests with ATS optics were achieved during the LHC Run I (2011/2012) for a first validation of the basics of the scheme at small intensity. In 2016, a new generation of more performing ATS optics was developed and more extensively tested in the machine, still with probe beams for optics measurement and correction at β*=10 cm, but also with a few nominal bunches to establish first collisions at nominal β* (40 cm) and beyond (33 cm), and to analysis the robustness of these optics in terms of collimation and machine protection. The paper will highlight the most relevant and conclusive results which were obtained during this second series of ATS tests.
[1] S. Fartoukh , Phys. Rev. ST Accel. Beams 16, 111002 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK030 | |
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| WEPIK093 | New Methods for Measurement of Nonlinear Errors in LHC Experimental IRs and Their Application in the HL-LHC | 3155 |
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| Studies of nonlinear errors in LHC experimental insertions (IRs) during Run 1 were based upon feed-down to tune and coupling from the crossing angle orbit bumps. Useful for validating the magnetic model, this method alone is of limited use to understand discrepancies between magnetic and beam-based measurement. Feed-down from high-order multipoles is also difficult to observe. During Run 2 several alternative methods were tested in the LHC. This paper summarizes the results of these tests, and comments on their potential application to the High-Luminosity LHC upgrade. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK093 | |
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| WEPVA037 | Machine Development Studies in the CERN PS Booster, in 2016 | 3339 |
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| The paper presents the outstanding studies performed in 2016 in preparation of the PS Booster upgrade, within the LHC Injector Upgrade project (LIU), to provide twice higher brightness and intensity to the High-Luminosity LHC. Major changes include the increase of injection and extraction energy, the implementation of a H− charge-exchange injection system, the replacement of the present Main Power Supply and the deployment of a new RF system (and related Low-Level), based on the Finemet technology. Although the major improvements will be visible only after the upgrade, the present machine can already benefit of the work done, in terms of better brightness, transmission and improved reproducibility of the present operational beams. Studies address the space-charge limitations at low energy, for which a detailed optics model is needed and for which mitigation measurements are under study, and the blow-up reduction at injection in the downstream machine, for which the beams need careful preparation and transmission. Moreover they address the requirements and the reliability of new beam instrumentation and hardware that is being installed in view of LIU. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA037 | |
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