| Paper | Title | Page |
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| MOPMR027 | Employing Beam-Gas Interaction Vertices for Transverse Profile Measurements | 296 |
| SUPSS073 | use link to see paper's listing under its alternate paper code | |
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Interactions of high-energy beam particles with residual gas offer a unique opportunity to measure the beam profile in a non-intrusive fashion. Such a method was successfully pioneered* at the LHCb experiment using a silicon microstrip vertex detector. During the recent Large Hadron Collider shutdown at CERN, a demonstrator Beam-Gas Vertexing system based on eight scintillating-fibre modules was designed**, constructed and installed on Ring 2 to be operated as a pure beam diagnostics device. The detector signals are read out and collected with LHCb-type front-end electronics and a DAQ system consisting of a CPU farm. Tracks and vertices will be reconstructed to obtain a beam profile in real time. Here, first commissioning results are reported. The advantages and potential for future applications of this technique are discussed.
* LHCb collaboration, Journal of Instrumentation, 9, P12005 ** P. Hopchev in Proc. of IPAC 2014, June 15-20, 2014, Dresden Germany |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR027 | |
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| TUPMW014 | Improved Aperture Measurements at the LHC and Results from their Application in 2015 | 1446 |
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| A good knowledge of the available aperture in the LHC is essential for a safe operation due to the risk of magnet quenches or even damage in case of uncontrolled beam losses. Experimental validations of the available aperture are therefore crucial and were in the past carried out by either a collimator scan combined with beam excitations or through the use of local orbit bumps. In this paper, we show a first comparison of these methods in the same machine configuration, as well as a new very fast method based on a beam-based collimator alignment and a new faster variant of the collimator scan method. The methods are applied to the LHC operational configuration for 2015 at injection and with squeezed beams and the measured apertures are presented. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW014 | |
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| TUPMW027 | The 2015 Heavy-Ion Run of the LHC | 1493 |
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| In late 2015 the LHC collided lead nuclei at a beam energy of 6.37 Z TeV, chosen to match the 5.02 TeV per colliding nucleon pair of the p-Pb collision run in 2013. In so doing, it surpassed its design luminosity by a factor of 2. Besides the higher energy, the operational configuration had a number of new features with respect to the previous Pb-Pb run at 3.5 Z TeV in 2011; unusual bunch patterns providing collisions in the LHCb experiment for the first time, luminosity levelling and sharing requirements, a vertical displacement of the interaction point in the ALICE experiment, and operation closer to magnet quench limits with mitigation measures. We present a summary of the commissioning and operation and what has been learned in view of future heavy-ion operation at higher luminosity. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW027 | |
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| WEOCA01 | Operation of the LHC with Protons at High Luminosity and High Energy | 2066 |
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| In 2015 the Large Hadron Collider (LHC) entered the first year in its second long Run, after a 2-year shutdown that prepared it for high energy. The first two months of beam operation were dedicated to setting up the nominal cycle for proton-proton operation at 6.5 TeV/beam, and culminated with the first physics with 3 nominal bunches/ring at 13 TeV CoM on 3 June. The year continued with a stepwise intensity ramp up that allowed reaching 2244 bunches/ring for a peak luminosity of ~5·1033 cm-2s−1 and a total of just above 4 fb-1 delivered to the high luminosity experiments. Beam operation was shaped by the high intensity effects, e.g. electron cloud and macroparticle-induced fast losses (UFOs), which on a few occasions caused the first beam induced quenches at high energy. This paper describes the operational experience with high intensity and high energy at the LHC, together with the issues that had to be tackled along the way. | ||
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Slides WEOCA01 [4.013 MB] | |
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA01 | |
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| THPMR038 | Non-Linear Errors in the Experimental Insertions of the LHC | 3472 |
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| Correction of nonlinear magnetic errors in low-β insertions can be of critical significance for the operation of a collider. This is expected to be of particular relevance to LHC Run II and the HL-LHC upgrade, as well as to future colliders such as the FCC. Current correction strategies for these accelerators have assumed it will be possible to calculate optimized local corrections through the insertions using a magnetic model of the errors. To test this assumption the nonlinear errors in the LHC experimental insertions have been examined via feed-down and amplitude detuning. It will be shown that while in some cases the magnetic measurements provide a sufficient description of the errors, in others large discrepancies exist which will require beam-based correction techniques. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR038 | |
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| THPMR043 | Performance of Transverse Beam Splitting and Extraction at the CERN Proton Synchrotron in the Framework of Multi-turn Extraction | 3492 |
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| Considerable progress has been made in 2015 in the setting up of the multi-turn extraction (MTE) in the CERN Proton Synchrotron (PS). A key ingredient in this novel extraction technique is the beam splitting in transverse phase space. This manipulation is based on adiabatic trapping in stable islands of transverse phase space and requires mastering a number of devices in the PS ring. In addition, an in-depth review of all fast extractions schemes in the PS had been required due to the development and installation of a dummy septum to shield the actual magnetic septum. In this paper, the current performance of the beam splitting and of the extraction including the shadowing effect is presented. Future lines of development will also be discussed. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR043 | |
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