Author: Bertarelli, A.
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MOPMF046 Simulation of Hydrodynamic Tunneling Caused by High Energy Proton Beam in Copper through Coupling of FLUKA and Autodyn 204
  • Y.C. Nie, A. Bertarelli, F. Carra, C. Fichera, L.K. Mettler, R. Schmidt, D. Wollmann
    CERN, Geneva, Switzerland
  For machine protection of high-energy colliders, it is important to assess potential damages caused to accelerator components in case large number of bunches are lost at the same place. The numerical assessment requires an iterative execution of an energy-deposition code and a hydrodynamic code, since the hydrodynamic tunneling effect will likely play an important role in the beam-matter interactions. For proton accelerators at CERN and for the Future Circular Collider (FCC), case studies were performed, coupling FLUKA and BIG2. To compare different hydrocodes and not to rely only on BIG2, FLUKA and a commercial tool, Autodyn, have been used to perform these simulations. This paper reports a benchmarking study against a beam test performed at the HiRadMat (High-Radiation to Materials) facility using beams at 440 GeV from the Super Proton Synchrotron. Good agreement has been found between the simulation results and the test as well as previous simulations with FLUKA and BIG2, particularly in terms of penetration depth of the beam in copper. This makes the coupling of FLUKA and Autodyn an alternative solution to simulating the hydrodynamic tunneling. More case studies are planned for FCC and other high-beam-power accelerators.  
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MOPMF053 Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2 228
  • J.M. Jimenez, D. Amorim, S. A. Antipov, G. Arduini, A. Bertarelli, N. Biancacci, B. Bradu, E. Bravin, G. Bregliozzi, K. Brodzinski, R. Bruce, X. Buffat, L.R. Carver, P. Chiggiato, S.D. Claudet, P. Collier, R. Garcia Alia, M. Giovannozzi, L. K. Grob, E.B. Holzer, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, B. Lindstrom, T. Medvedeva, A. Milanese, D. Mirarchi, E. Métral, D. Perini, S. Redaelli, G. Rumolo, B. Salvant, R. Schmidt, M. Valette, D. Valuch, J. Wenninger, D. Wollmann, C. Yin Vallgren, C. Zamantzas, M. Zerlauth
    CERN, Geneva, Switzerland
  • D. Amorim
    Université Grenoble Alpes, Grenoble, France
  • A.A. Gorzawski
    University of Manchester, Manchester, United Kingdom
  • L. Mether
    EPFL, Lausanne, Switzerland
  Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run.  
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WEPMF071 Dynamic Testing and Characterization of Advanced Materials in a New Experiment at CERN HiRadMat Facility 2534
  • A. Bertarelli, C. Accettura, E. Berthomé, L. Bianchi, F. Carra, C. Fichera, M.I. Frankl, G. Gobbi, P. Grosclaude, M. Guinchard, A. Lechner, M. Pasquali, S. Redaelli, E. Rigutto, O. Sacristan De Frutos
    CERN, Geneva, Switzerland
  • Ph. Bolz, P. Simon
    GSI, Darmstadt, Germany
  • T.R. Furness
    University of Huddersfield, Huddersfield, United Kingdom
  • J. Guardia Valenzuela
    Universidad de Zaragoza, Zaragoza, Spain
  • P. Mollicone, M. Portelli
    UoM, Msida, Malta
  Funding: This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
An innovative and comprehensive experiment (named "Multimat") was successfully carried out at CERN HiRadMat facility on 18 different materials relevant for Collimators and Beam Intercepting Devices. Material samples, tested under high intensity proton pulses of 440 GeV/c, exceeding the energy density expected in HL-LHC, ranged from very light carbon foams to tungsten heavy alloys, including novel composites as graphite/carbides and metal/diamond without and with thin-film coatings. Experimental data were acquired relying on extensive integrated instrumentation (strain gauges, temperature sensors, radiation-hard camera) and on laser Doppler vibrometer. This allows investigating relatively unexplored and fundamental phenomena as dynamic strength, internal energy dispersion, nonlinearities due to inelasticity and inhomogeneity, strength and delamination of coatings and surfaces. By benchmarking sophisticated numerical simulations against these results, it is possible to establish or update material constitutive models, which are of paramount importance for the design of devices exposed to interaction with particle beams in high energy accelerators such as the HL-LHC or FCC-hh.
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WEPMF081 Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature - R&D Study and Applications 2572
  • M. Guinchard, A. Bertarelli, L. Bianchi, F.B. Boyer, M. Cabon, M. Calviani, O. Capatina, A. Catinaccio, P. Ferracin, P. Grosclaude
    CERN, Geneva, Switzerland
  In recent years, optical fiber sensors have been increasingly used due to their outstanding performances. Their application is preferable in case of special requirements that exclude the application of conventional electrical sensors. The scientific background of optical fiber sensors is well developed. However, the characteristic of sensors employed in rather harsh environments is often different from the one determined in laboratory conditions or prior to their installation. In order to achieve long-term stable functioning and reliable measurement under severe working environments, such as those occurring at CERN (radiation, cryogenics, high magnetic and electrical field), a statistical measurement campaign was carried out following the international standard ISO 5725. The paper describes the ongoing study to define the accuracy of optical fiber sensors based on Fiber Bragg Grating (FBG) for strain measurements, from room temperature down to 4.2 K. It also describes some of the demanding applications for which optical fiber sensors have been deployed to perform experimental strain measurements (e.g. detectors components, high-energy beam targets and dumps, superconducting magnets).  
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