Bonding of lead shielding directly on to the aluminum vacuum chambers of the LEP machine

Bunches of electrons and positrons circulating in the LEP vacuum system will emit very intense x-rays (synchrotron radiation). To ensure that the radiation level in the tunnel is kept within permissible limits, a complete radiation shielding of the vacuum system has to be envisaged. The necessary shielding is effected by bonding tinned lead profiles directly to the aluminum chambers using a tin lead solder joint and, in addition, preformed lead shells are fitted at chamber extremities. A description of the bonding process adopted by industry for some 2638 chambers up to 12 metres long is given together with interim bonding efficiency results obtained by ultrasonic examination of the Pb/Al interfaces. Unforeseen bonding problems encountered during the industrial phase will also be reported