Synchrotron Radiation Lead Shielding of the Vacuum Chambers for LEP

The high linear power density and the energetic photon spectrum in LEP impose a complete radiation shield around the vacuum chamber. The absorption and scattering of the photons in the vacuum chamber has been studied with the use of the Monte Carlo shower program EGS in view of defining the lead shielding required for acceptable dose levels. To avoid the excessive production of ozone or of corrosive products in the air surrounding the vacuum chamber it is proposed to apply the lead shield directly onto the aluminium profile. In this way the cooling circuits of the vacuum chamber can cool the lead shield which will later be necessary at increased LEP energies. Different methods of bonding the lead to the aluminium have been studied and have resulted in a cladding process using a tin-lead solder joint. This method has been applied to aluminium tubes of up to 12 m length and to full size prototype vacuum chambers.