# All CERN Accelerators documents

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2022-01-14
13:53
 Differential Cross Section Measurement of the $pp\rightarrow WH\rightarrow WWW$ Process With the ATLAS Experiment / Hesping, Moritz Elias In this thesis, a Simplified Template Cross Section (STXS) analysis for the $pp\rightarrow WH\rightarrow WWW\rightarrow l\nu l\nu l\nu$ process is presented, using final states with no lepton pairs of the same flavor and opposite charge. The analysis uses proton-proton collisions at a center of mass energy of $13~TeV$ with an integrated luminosity of $139~fb^{-1}$, which were measured by the ATLAS detector at the Large Hadron Collider. [...] CERN-THESIS-2021-251.- Fulltext: PDF; External link: Approve this document (restricted)

2022-01-13
06:16
 RF system challenges for future  ${e}^+ {e}^-$ circular colliders / Brunner, Olivier (CERN) ; Jensen, Erk (CERN) ; Karpov, Ivan (CERN) ; Montesinos, Eric (CERN) ; Peauger, Franck (CERN) ; Syratchev, Igor (CERN) The RF system is the centrepiece of any future circular lepton collider. In particular, the system is required to support the high intensity beams needed for pushing the luminosity at the lower energy regimes of future energy-frontier circular lepton colliders (e.g. [...] 2021 - 11 p. - Published in : Eur. Phys. J. Plus 137 (2022) 73 Fulltext: PDF;

2022-01-13
06:16
 General mitigation techniques for coherent beam instabilities in particle accelerators / Métral, Elias (CERN) An important number of coherent beam instability mechanisms can be observed in a particle accelerator, depending if the latter is linear or circular, operated at low, medium or high energy, with a small or a huge amount of turns (for circular machines), close to transition energy or not (below or above), with only one bunch or many bunches, with counter-rotating beams (such as in colliders) or not, if the beam is positively or negatively charged, if one is interested in the longitudinal plane or in the transverse plane, in the presence of linear coupling between the transverse planes or not, in the presence of nonlinearities or not, in the presence of noise or not, etc. Building a realistic impedance model of a machine is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics (linear and nonlinear), RF gymnastics, transverse damper, noise, space charge, electron cloud, and beam–beam (in a collider). [...] 2021 - 23 p. - Published in : Eur. Phys. J. Plus 137 (2022) 47 Fulltext: PDF;

2022-01-12
12:21
 How the distance of the cavern walls affects the background rates / Ferro-Luzzi, Massimiliano (CERN) /SHiP Collaboration to be added CERN-SHiP-INT-2022-001.- Geneva : CERN, 2022

2022-01-12
06:18
 First “Skin Depth” estimations using GEANT4 and FLUKA based simulations for CERN secondary beamlines / D'Alessandro, Gian Luigi (CERN ; Royal Holloway, U. of London) ; Banerjee, Dipanwita (CERN) ; Gatignon, Lau (CERN) ; Bernhard, Johannes (CERN) ; Gerbershagen, Alexander (CERN) ; van Dijk, Maarten (CERN ; Ecole Polytechnique, Lausanne) ; Gibson, Stephen (Royal Holloway, U. of London) In order to have highly flexible secondary beamlines collimation is crucial. Collimators are blocks of material placed along the beamline that let the main beam pass within the collimator aperture limits, while most of the particles beyond it interact in the material and gets absorbed or loses enough energy to be deflected away from the beam core by the magnets placed downstream. [...] 2022 - 7 p. - Published in : Nucl. Instrum. Methods Phys. Res., B 512 (2022) 76-82 Fulltext: PDF;

2022-01-12
06:18
 Development of a rotating-coil scanner for superconducting accelerator magnets / Rogacki, Piotr (CERN ; RWTH Aachen U.) ; Fiscarelli, Lucio (CERN) ; Russenschuck, Stephan (CERN) ; Hameyer, Kay (RWTH Aachen U.) The High-Luminosity upgrade project for the Large Hadron Collider (HL-LHC) at CERN (Conseil Européen pour la Recherche Nucléaire) will require new superconducting magnets for the insertion regions. Among these magnets, the new triplet quadrupoles, based on Nb3Sn technology, require magnetic-field measurements of a high precision in the field angle and multipole field errors. [...] 2020 - 9 p. - Published in : Journal of Sensors and Sensor Systems 9 (2020) 99-107 Fulltext: PDF;

2022-01-12
06:18
 A Safety System for Human Radiation Protection and Guidance in Extreme Environmental Conditions / Adamidi, Eleni S (Natl. Tech. U., Athens) ; Gazis, Evangelos N (Natl. Tech. U., Athens ; CERN) ; Nikita, Konstantina S (Natl. Tech. U., Athens) We present a safety system designed to ensure human radiation protection and provide real-time guidance in extreme environmental conditions. This system was developed and tested in the complex experimental infrastructure of the ATLAS underground cavern at CERN, where personnel safety is crucial, especially during maintenance periods. [...] 2020 - 11 p. - Published in : IEEE Systems Journal 14 (2020) 1384-1394

2022-01-12
06:18
 Evaluation of the nonlinear surface resistance of REBCO coated conductors for their use in the FCC-hh beam screen / Krkotić, P (CELLS - ALBA, LLS ; Barcelona, Polytechnic U.) ; Romanov, A (Barcelona, Autonoma U.) ; Tagdulang, N (CELLS - ALBA, LLS ; Barcelona, Polytechnic U.) ; Telles, G (Barcelona, Autonoma U.) ; Puig, T (Barcelona, Autonoma U.) ; Gutierrez, J (Barcelona, IFAE) ; Granados, X (Barcelona, Autonoma U.) ; Calatroni, S (CERN) ; Perez, F (CELLS - ALBA, LLS) ; Pont, M (CELLS - ALBA, LLS) et al. To assess the feasibility of using high-temperature superconductors for the beam screens of future circular colliders, we have undertaken a study of the power dependence of the microwave surface resistance in state-of-the-art REBCO coated conductors at about 8 GHz and 50 K. We have employed a dielectric resonator to produce radio-frequency (RF) electromagnetic fields on the surface of the coated conductors having amplitudes similar to those generated by proton bunches circulating in the vacuum chamber of the proposed future circular collider Hadron-Hadron (FCC-hh) at CERN We show that surface resistances in REBCO coated conductors without artificial pinning centers are more affected by a RF magnetic field than those containing nano-inclusions. [...] 2022 - 11 p. - Published in : Supercond. Sci. Technol. 35 (2022) 025015 Fulltext: PDF;

2022-01-12
06:18
 Application of Thomson scattering to helicon plasma sources / Agnello, R (Ecole Polytechnique, Lausanne) ; Andrebe, Y (Ecole Polytechnique, Lausanne) ; Arnichand, H (Ecole Polytechnique, Lausanne) ; Blanchard, P (Ecole Polytechnique, Lausanne) ; De Kerchove, T (Ecole Polytechnique, Lausanne) ; Furno, I (Ecole Polytechnique, Lausanne) ; Howling, A A (Ecole Polytechnique, Lausanne) ; Jacquier, R (Ecole Polytechnique, Lausanne) ; Sublet, A (CERN) The possibility of performing electron density and temperature measurements in a high power helicon plasma is a crucial issue in the framework of the AWAKE (Advanced WAKefield Experiment) project, which demonstrates acceleration of particles using GeV m$^{-1}$ electric fields in plasmas. For AWAKE, a helicon is currently envisaged as a candidate plasma source due to its capability for low electron and ion temperature, high electron density and production of an elongated plasma column. [...] 2020 - 18 p. - Published in : J. Plasma Phys. 86 (2020) 905860306

2022-01-12
04:13
 High intensity proton beam impact at 440 GeV/c on Mo and Cu coated CfC/graphite and SiC/SiC absorbers for beam intercepting devices / Maestre, Jorge (CERN ; Granada U.) ; Bahamonde, Cristina (CERN) ; Garcia, Inigo Lamas (CERN) ; Kershaw, Keith (CERN) ; Biancacci, Nicolo (CERN) ; Busom, Josep (CERN) ; Frankl, Matthias (CERN ; PSI, Villigen) ; Lechner, Anton (CERN) ; Kurtulus, Adnan (CERN) ; Makimura, Shunsuke (J-PARC ; KEK, Tsukuba) et al. Beam Intercepting Devices (BIDs) are essential protection elements for the operation of the Large Hadron Collider (LHC) complex. [...] arXiv:2112.04792. - 34 p. Fulltext