Author: Holzer, E.B.
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MOPMR024 A Versatile Beam Loss Monitoring System for CLIC 286
SUPSS070   use link to see paper's listing under its alternate paper code  
  • M. Kastriotou, S. Döbert, W. Farabolini, E.B. Holzer, E. Nebot Del Busto, F. Tecker
    CERN, Geneva, Switzerland
  • M. Kastriotou, E. Nebot Del Busto, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • M. Kastriotou, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  The design of a potential CLIC beam loss monitoring (BLM) system presents multiple challenges. To successfully cover the 48 km of beamline, ionisation chambers and optical fibre BLMs are under investigation. The former fulfils all CLIC requirements but would need more than 40000 monitors to protect the whole facility. For the latter, the capability of reconstructing the original loss position with a multi-bunch beam pulse and multiple loss locations still needs to be quantified. Two main sources of background for beam loss measurements are identified for CLIC. The two-beam accelerator scheme introduces so-called crosstalk, i.e. detection of losses originating in one beam line by the monitors protecting the other. Moreover, electrons emitted from the inner surface of RF cavities and boosted by the high RF gradients may produce signals in neighbouring BLMs, limiting their ability to detect real beam losses. This contribution presents the results of dedicated experiments performed in the CLIC Test Facility to quantify the position resolution of optical fibre BLMs in a multi-bunch, multi-loss scenario as well as the sensitivity limitations due to crosstalk and electron field emission.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR024  
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TUPMR027 CERN's Fixed Target Primary Ion Programme 1297
  • D. Manglunki, M.E. Angoletta, J. Axensalva, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, S. Cettour-Cave, K. Cornelis, H. Damerau, I. Efthymiopoulos, A. Fabich, J.A. Ferreira Somoza, A. Findlay, P. Freyermuth, S.S. Gilardoni, S. Hancock, E.B. Holzer, S. Jensen, V. Kain, D. Küchler, A.M. Lombardi, A.I. Michet, M. O'Neil, S. Pasinelli, R. Scrivens, R. Steerenberg, G. Tranquille
    CERN, Geneva, Switzerland
  The renewed availability of heavy ions at CERN for the needs of the LHC programme has triggered the interest of the fixed-target community. The project, which involves sending several species of primary ions at various energies to the North Area of the Super Proton Synchrotron, has now entered its operational phase. The first argon run, with momenta ranging from 13 AGeV/c to 150 AGeV/c, took place from February 2015 to April 2015. This paper presents the status of the project, the performance achieved thus far and an outlook on future plans.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR027  
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TUPMW023 Macroparticle-Induced Losses During 6.5 TeV LHC Operation 1481
  • G. Papotti, M. Albert, B. Auchmann, E.B. Holzer, M.K. Kalliokoski, A. Lechner
    CERN, Geneva, Switzerland
  One of the major performance limitations for operating the LHC at high energy was feared to be the so called UFOs (Unidentified Falling Objects, presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam). Indeed much higher rates were observed in 2015 compared to Run 1, and about 20 fills were prematurely terminated by too high losses caused by such events. Additionally they triggered a few beam induced quenches at high energy, the first in the history of the LHC. In this paper we review the latest update on the analysis of these events, e.g. the conditioning observed during the year and possible correlations with beam and machine parameters. At the same time we also review the optimization of beam loss monitor thresholds in terms of machine protection and availability.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW023  
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