Magnetic and electric field effects on the photoelectron emission from prototype LHC beam screen material

This paper describes the experimental studies of the effect of a dipole fie ld on photoelectron emission and on the photon reflectivities from LHC beam screen material. These studies were performed using synchrotron radiation from the VEPP-2M storage ring at BINP (Novosibirsk), The particular surface roughness and geometry of the prototype LHC beam screen material requires dedicated experimental measurements. The experiments were performed under c onditions close to those expected in the LHC, An important result obtained is that a dipole magnetic field attenuates the photoelectron emission from the surface by more than two orders of magnitude with the magnetic held ali gned parallel to the surface. The measurements of photon reflectivities, fo rward scattered and diffuse, and the azimuthal distribution of emitted phot oelectrons from the same material are reported. These experimental results are important input for the final design of the LHC beam screen. (C) 2001 E lsevier Science Ltd. All rights reserved.