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CERN Yellow Report Articles

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2021-02-09
04:01
Review of impedance-induced instabilities and their possible mitigation techniques / Migliorati, M. (Rome U. ; INFN, Rome) ; Métral, E. (CERN) ; Zobov, M. (Frascati)
In this paper a review of some important impedance-induced instabilities are briefly described for both the longitudinal and transverse planes. The main tools used nowadays to predict these instabilities and some considerations about possible mitigation techniques are also presented..
arXiv:2003.07615.- 2020-12-16 - 8 p. - Published in : 10.23732/CYRCP-2020-009.1 Fulltext: 2003.07615 - PDF; fulltext1785861 - PDF;
In : ICFA mini-Workshop on Mitigation of Coherent Beam Instabilities in Particle Accelerators (MCBI 2019), Zermatt, Switzerland, 23 - 27 Sep 2019, pp.1 (CERN-2020-009)

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2021-01-27
06:31
Chapter 13: Beam instrumentation and long-range beam–beam compensation / Jones, R (CERN) ; Bravin, Enrico (CERN) ; Lefevre, Thibault (CERN) ; Veness, Raymond (CERN)
The extensive array of beam instrumentation with which the LHC is equipped has played a major role in its commissioning, rapid intensity ramp-up and safe and reliable operation. Much of this equipment will need consolidation by the time the LHC enters the High-Luminosity (HL) era, while the upgrade itself brings a number of new challenges. The installation of a completely new final focus system in the two high-luminosity LHC insertions implies the development of new beam position monitors to equip the upgraded quadrupole magnets. [...]
2020 - 14 p. - Published in : 10.23731/CYRM-2020-0010.245 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 2: Machine layout and performance / Arduini, G (CERN) ; Bruce, R (CERN) ; De Maria, R (CERN) ; Giovannozzi, M (CERN) ; Iadarola, G (CERN) ; Jowett, J (CERN) ; Métral, E (CERN) ; Papaphilippou, Y (CERN) ; Garcia, R Tomás (CERN)
The goal of the High-luminosity upgrade of the LHC is to deliver an integrated luminosity of at least 250 fb-1 per year (assuming at least 160 days of operation at high-luminosity) in each of the two high-luminosity general-purpose detectors, ATLAS and CMS, located at the interaction points (IP) 1 and 5, respectively. The ATLAS and CMS detectors will be upgraded to handle an average pile-up, the number of events per bunch crossing, of at least 140 (ultimately 200), corresponding to an instantaneous luminosity of approximately 5 × 1034 cm-2 s-1 (ultimately 7.5 × 1034 cm-2 s-1) for operation with 25 ns beams consisting of 2760 bunches at 7 TeV, and for an inelastic cross-section σin = 81 mb. [...]
2020 - 30 p. - Published in : 10.23731/CYRM-2020-0010.17 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 1: High-Luminosity Large Hadron Collider / Brüning, O (CERN) ; Rossi, L (CERN ; U. Milan (main) ; LASA, Segrate)
The Large Hadron Collider (LHC) was successfully commissioned in 2010 for proton–proton collisions with a 7 TeV centre-of-mass (c.o.m.) energy. It delivered 8 TeV c.o.m. [...]
16 p. - Published in : 10.23731/CYRM-2020-0010.1 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 3: Insertion Magnets / Todesco, E (CERN) ; Ferracin, P (CERN)
In general, magnets will be tested individually in a vertical test station, and then horizontally in the final cold mass assembly within the final cryostat, with the exception of Q2 and D2 whose length does not allow vertical testing. Many power tests will be done in laboratories collaborating with CERN (BNL for vertical test of Q1/Q3, FNAL for horizontal test of Q1/Q3, KEK for vertical test of D1, LASA for vertical test of high order correctors, IMP (Lanzhou-China) for vertical test of D2 correctors, FREIA (Univ. [...]
2020 - 18 p. - Published in : 10.23731/CYRM-2020-0010.47 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 4: RF systems / Calaga, R (CERN) ; Baudrenghien, P (CERN) ; Capatina, Ofelia (CERN) ; Jensen, Erk (CERN) ; Montesinos, Eric (CERN)
The HL-LHC beams are injected, accelerated, and stored to their nominal energy of 7 TeV by the existing 400 MHz superconducting RF system of the LHC. A novel superconducting RF system consisting of eight cavities per beam for transverse deflection (aka crab cavities) of the bunches will be used to compensate the geometric loss in luminosity due to the non-zero crossing angle and the extreme focusing of the bunches in the HL-LHC. Due to doubling of the beam currents in the HL-LHC era, an optimal detuning scheme (aka full- detuning) is required to cope with the transient beam loading effects. A modulation of the klystron and cavity phase make the phase of bunches with respect to the RF clock to progressively slip along the bunch train, but then recover during the abort gap. [...]
2020 - 22 p. - Published in : 10.23731/CYRM-2020-0010.65 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 5: Collimation system / Redaelli, Stefano (CERN) ; Bruce, Roderik (CERN) ; Lechner, Anton (CERN) ; Mereghetti, Alessio (CERN)
A variety of processes can cause unavoidable beam losses during normal and abnormal beam operation. Because of the high stored energy of about 700 MJ and the small transverse beam sizes, the HL-LHC beams are highly destructive. [...]
2020 - 27 p. - Published in : 10.23731/CYRM-2020-0010.87 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 6: Circuit layout, powering and protection / Rodríguez Mateos, F (CERN) ; Catalão Rolhas da Rosa, T D (CERN) ; Menéndez Cámara, F (CERN) ; Yammine, S (CERN) ; Zerlauth, Markus (CERN)
During LS2 and LS3, the HL-LHC upgrade will impose many changes to the magnet circuits of the LHC long- straight sections at points 1 and 5. The magnets will be installed in the machine during LS3. [...]
2020 - 14 p. - Published in : 10.23731/CYRM-2020-0010.115 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 6A: Cold powering of the superconducting circuits / Ballarino, Amalia (CERN) ; Cruikshank, Paul (CERN) ; Fleiter, Jerome Christophe (CERN) ; Leclercq, Yann Raphael Bruno (CERN) ; Parma, V (CERN) ; Yang, Y (U. Southampton (main))
For the HL-LHC project, a novel concept for the cold powering of superconducting magnets has been developed. It is based on a new type of superconducting lines (hereafter referred to as Superconducting (SC) Links) that have been developed to transfer the current to the new HL-LHC insertion region magnets from remote distances. [...]
2020 - 9 p. - Published in : 10.23731/CYRM-2020-0010.129 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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2021-01-27
06:31
Chapter 6B: Warm powering of the superconducting circuits / Martino, M (CERN) ; Burnet, J-P (CERN) ; Cerqueira Bastos, M   (CERN) ; Herrero Gonzales, V R   (CERN) ; Kuczerowski, N (CERN) ; Pittet, S (CERN) ; Thiesen, H (CERN) ; Thurel, Y (CERN) ; Todd, B (CERN) ; Yammine, S (CERN)
The warm powering of the HL-LHC involves the new circuits of the Inner Triplets and the Separation/Recombination magnets in Point 1 and Point 5, the powering of the 11 T magnets in Point 7, and the final R2E consolidation phase in LS3. The LHC was built with modular power converters to facilitate maintenance and integrate the redundancy principle. [...]
2020 - 14 p. - Published in : 10.23731/CYRM-2020-0010.139 Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report

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