Observation of channeling in bent crystals at the CERN LHC

Roberto Rossi,Stefano Redaelli,Daniele Mirarchi,Germogli Germogli,Iouri M Ivanov,Anton Lechner,Mark Butcher,Gianluca Valentino,Yury A Gavrikov,A A Yanovic,G Cavoto ,V V Skorobogatov,M Pesaresi ,A Stocchi ,S Gilardoni ,L Bandiera ,V Puill ,V Guidi ,L.p Lapina ,P Schoofs ,F Cerutti ,Yury A Chesnokov ,S.b Dabagov ,W Scandale ,G Hall ,V Chaumat ,Yury E Sandomirskiy,A Durum ,V A Maisheev ,G Arduini ,L Ludovici ,L Burmistrov ,A Masi ,A.s Denisov ,Thomas C Jones ,R Losito ,A D Kovalenko,F Galluccio ,A Mazzolari ,A.m Taratin ,A G Afonin ,G.i Smirnov ,M Garattini ,R Santacesaria ,D Bretón ,Francesca Maria Addesa ,S Montesano ,S Dubos ,P Valente ,L.g Malyarenko ,Jihane Maalmi ,F Iacoangeli ,F Murtas ,E Bagli ,M Raymond

doi:10.22323/1.282.0867

Abstract

The feasibility of crystal-assisted collimation is being investigated for improvements of the LHC collimation system, as a part of the future high luminosity upgrade of the CERN LHC (HL-LHC). Two high-accuracy goniometers, each equipped with one bent silicon crystal, were installed in the betatron cleaning insertion of the LHC in 2014. During dedicated tests in 2015, bent crystals were approached to the circulating the beams to test their usage as a first stage in a crystal-based system, both with proton and Pb ion beams. Tests were performed with protons at injection energy (450 GeV/c) and at flat top (6.5 TeV/c), and with ions at injection energy (450 Z GeV/c). A reduction of losses immediately downstream of the crystals was observed in optimum channeling orientation, demonstrating for the first time channeling at these energies. Halo cleaning efficiency of the crystal-based collimation system was also measured.

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