High Luminosity LHC: challenges and plans

Arduini, G.; Barranco, J.; Bertarelli, A.; Biancacci, Nicolò; Bruce, Roderik; Brüning, Oliver; Buffat, Xavier; Cai, Yunhai; Carver, Lee; Fartoukh, S.; Giovannozzi, M.; Iadarola, Giovanni; Li, K.; Lechner, Anton; Medrano, Luis Medina; Métral, E.; Nosochkov, Y.; Papaphilippou, Y.; Pellegrini, Dario; Pieloni, Tatiana; Qiang, Ji; Redaelli, Stefano; Romano, Annalisa; Rossi, L.; Rumolo, G.; Salvant, Benoît; Schenk, Michael; Tambasco, Claudia; Tomás, Rogelio; Valishev, Sasha; Veken, Frederik F. Van der

doi:10.1088/1748-0221/11/12/c12081

Cited by 19 publications

(11 citation statements)

References 24 publications

(25 reference statements)

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“…Although this performance is very satisfactory, further improvements are deemed necessary for the high-luminosity upgrade (HL-LHC) of the LHC [5][6][7][8] that aims at achieving about 700 MJ stored energies. Also note that the halo cleaning efficiency is drastically reduced with heavy ion beams, where a worsening of a factor about 100 is observed with respect to proton beams.…”

Section: Introductionmentioning

confidence: 99%

Design and implementation of a crystal collimation test stand at the Large Hadron Collider

et al. 2017

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Future upgrades of the CERN Large Hadron Collider (LHC) demand improved cleaning performance of its collimation system. Very efficient collimation is required during regular operations at high intensities, because even a small amount of energy deposited on superconducting magnets can cause an abrupt loss of superconducting conditions (quench). The possibility to use a crystal-based collimation system represents an option for improving both cleaning performance and impedance compared to the present system. Before relying on crystal collimation for the LHC, a demonstration under LHC conditions (energy, beam parameters, etc.) and a comparison against the present system is considered mandatory. Thus, a prototype crystal collimation system has been designed and installed in the LHC during the Long Shutdown 1 (LS1), to perform feasibility tests during the Run 2 at energies up to 6.5 TeV. The layout is suitable for operation with proton as well as heavy ion beams. In this paper, the design constraints and the solutions proposed for this test stand for feasibility demonstration of crystal collimation at the LHC are presented. The expected cleaning performance achievable with this test stand, as assessed in simulations, is presented and compared to that of the present LHC collimation system. The first experimental observation of crystal channeling in the LHC at the record beam energy of 6.5 TeV has been obtained in 2015 using the layout presented (Scandale et al., Phys Lett B 758:129, 2016). First tests to measure the cleaning performance of this test stand have been carried out in 2016 and the detailed data analysis is still on-going.

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Section: Introductionmentioning

confidence: 99%

Design and implementation of a crystal collimation test stand at the Large Hadron Collider

et al. 2017

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“…Starting from the beginning of June 2016, the vertical chromaticity (Q [7,8], this approach provided a sufficient mitigation against the beam instability and allowed storing stable 72-bunch trains into LHC. The beneficial impact of the chromaticity on the beam stability is shown in Fig.…”

Section: Experimental Observationsmentioning

confidence: 99%

Electron cloud buildup driving spontaneous vertical instabilities of stored beams in the Large Hadron Collider

Romano

Buffat

Iadarola

et al. 2018

Phys. Rev. Accel. Beams

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At the beginning of the 2016 run, an anomalous beam instability was systematically observed at the CERN Large Hadron Collider (LHC). Its main characteristic was that it spontaneously appeared after beams had been stored for several hours in collision at 6.5 TeV to provide data for the experiments, despite large chromaticity values and high strength of the Landau-damping octupole magnet. The instability exhibited several features characteristic of those induced by the electron cloud (EC). Indeed, when LHC operates with 25 ns bunch spacing, an EC builds up in a large fraction of the beam chambers, as revealed by several independent indicators. Numerical simulations have been carried out in order to investigate the role of the EC in the observed instabilities. It has been found that the beam intensity decay is unfavorable for the beam stability when LHC operates in a strong EC regime.

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“…Applications in high energy physics, medicine, security, and environmental monitoring require more and more accurate and sensitive devices to accomplish new challenging goals. The high luminosity perspective of the Large Hadron Collider (LHC) [1] and the construction of the new PANDA detector [2] request great efforts in producing high-quality and homogeneous components for both accelerators and detectors [3]. In fact, the response of the electromagnetic calorimeters is critically determined by the performances of the scintillator crystals.…”

Section: Introductionmentioning

confidence: 99%

“…Underestimating this factor may impair the whole system efficiency. In particular, PbWO 4 (PWO) crystals, used in the complex experiment Compact Muon Solenoid (CMS) electromagnetic calorimeter and PANDA [1,2], require suitable, reliable and repeatable mechanical operations for cutting and polishing in order to guarantee the proper surface finishing state which influences the crystal optical properties such as light yield, optical transmission and energy resolution [15].…”

Section: Introductionmentioning

confidence: 99%

Influence of a Surface Finishing Method on Light Collection Behaviour of PWO Scintillator Crystals

et al. 2018

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In the field of scintillators, high scintillation and light production performance require high-quality crystals. Although the composition and structure of crystals are fundamental in this direction, their ultimate optical performance is strongly dependent on the surface finishing treatment. This paper compares two surface finishing methods in terms of the final structural condition of the surface and the relative light yield performances. The first polishing method is the conventional “Mechanical Diamond Polishing” (MDP) technique. The second polishing technique is a method applied in the electronics industry which is envisaged for finishing the surface treatment of scintillator crystals. This method, named “Chemical Mechanical Polishing” (CMP), is efficient in terms of the cost and material removal rate and is expected to produce low perturbed surface layers, with a possible improvement of the internal reflectivity and, in turn, the light collection efficiency. The two methods have been applied to a lead tungstate PbWO4 (PWO) single crystal due to the wide diffusion of this material in high energy physics (CERN, PANDA project) and diagnostic medical applications. The light yield (LY) values of both the MDP and CMP treated crystals were measured by using the facilities at CERN while their surface structure was investigated by Scanning Electron Microscopy (SEM) and Grazing Incidence X-ray Diffraction (GID). We present here the corresponding optical results and their relationship with the processing conditions and subsurface structure.

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High Luminosity LHC: challenges and plans

Cited by 19 publications

References 24 publications

Design and implementation of a crystal collimation test stand at the Large Hadron Collider

Design and implementation of a crystal collimation test stand at the Large Hadron Collider

Electron cloud buildup driving spontaneous vertical instabilities of stored beams in the Large Hadron Collider

Influence of a Surface Finishing Method on Light Collection Behaviour of PWO Scintillator Crystals

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