Observation of channeling for 6500 GeV/ c protons in the crystal assisted collimation setup for LHC

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

doi:10.1016/j.physletb.2016.05.004

W Scandale, F Cerutti + Show 53 more

Open Access

https://doi.org/10.1016/j.physletb.2016.05.004

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Abstract

Abstract Two high-accuracy goniometers equipped with two bent silicon crystals were installed in the betatron cleaning insertion of the CERN Large Hadron Collider (LHC) during its long shutdown. First beam tests were recently performed at the LHC with 450 GeV/ c and 6500 GeV/ c stored proton beams to investigate the feasibility of beam halo collimation assisted by bent crystals. For the first time channeling of 6500 GeV/ c protons was observed in a particle accelerator. A strong reduction of beam losses due to nuclear inelastic interactions in the aligned crystal in comparison with its amorphous orientation was detected. The loss reduction value was about 24. Thus, the results show that deflection of particles by a bent crystal due to channeling is effective for this record particle energy.

Highlights

In the Large Hadron Collider (LHC), a multi-stage collimation system is used to absorb a growing halo of the circulating beams and to ensure a reliable operation below quench limits of superconducting magnets [1]
A single bunch with 1011 protons was injected in our first run on the LHC collimation studies with bent crystals
Two first scans were made with a goniometer rotation speed of 0.5 μrad/s when all collimators upstream the crystal were in their standard injection positions

Summary

Introduction

In the Large Hadron Collider (LHC), a multi-stage collimation system is used to absorb a growing halo of the circulating beams and to ensure a reliable operation below quench limits of superconducting magnets [1]. The experiment UA9 studying crystal assisted collimation at the CERN Super Proton Synchrotron (SPS) [7,8,9,10,11] showed strong reduction of the collimation leakage when the crystal deflector is in channeling conditions [11]. Perfect alignment of the crystal to have deflection of halo particles due to channeling was always obtained quickly by using information from the beam loss monitors (BLM) installed downstream of the crystal. The collimation leakage was measured by the beam loss monitor installed in the first high dispersion (HD) area downstream of the collimator–absorber, where off-momentum particles have the first possibility to hit the beam pipe after interacting with the crystal and the absorber. This observation opens new roads for high-energy beam manipulation in hadron colliders

The experiment description

Experimental results

Conclusions