CERN Accelerating science

Article
Report number	CERN-AB-2004-012-ABP ; GSI-ACC-NOTE-2004-02-001 ; LBNL-54594 ; SLAC-PUB-10350
Title	Can low energy electrons affect high energy physics accelerators?
Author(s)	Cimino, R (LNF-INFN, Frascati ; CERN) ; Collins, I R (CERN) ; Furman, M A (LBNL, Berkeley) ; Pivi, M (SLAC Stanford) ; Ruggiero, F (CERN) ; Rumolo, Giovanni (GSI, Darmstadt) ; Zimmermann, Frank (CERN)
Publication	2004
Imprint	11 Feb 2004
Number of pages	5
Note	revised version submitted on 2004-05-24 16:09:18
In:	Phys. Rev. Lett. 93 (2004) 014801/1-4
DOI	10.1103/PhysRevLett.93.014801
Subject category	Particle Physics - Theory
Abstract	The properties of the electrons participating in the build up of an electron cloud (EC) inside the beam-pipe have become an increasingly important issue for present and future accelerators whose performance may be limited by this effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. Thus, the accurate modeling of these surface properties is an indispensible input to simulation codes aimed at the correct prediction of build-up thresholds, electron-induced instability or EC heat load. In this letter, we present the results of surface measurements performed on a prototype of the beam screen adopted for the Large Hadron Collider (LHC), which presently is under construction at CERN. We have measured the total secondary electron yield (SEY) as well as the related energy distribution curves (EDC) of the secondary electrons as a function of incident electron energy. Attention has been paid, for the first time in this context, to the probability at which low-energy electrons (< 20 eV) impacting on the wall create secondaries or are elastically reflected. It is shown that the ratio of reflected to true-secondary electrons increases for decreasing energy and that the SEY approaches unity in the limit of zero primary electron energy.

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