No More Bricks in the Wall
To make room for research and to eliminate a seismic hazard, crews are removing the 30-foot-tall wall that separates End Station B from the B-line Target Room. In all, they are taking out more than 500 tons of shielding material, including a 12 x 30-foot beam dump, an old beam target and other equipment.
For safety, caution tape has prevented people and experiments in End Station B from coming within 15 feet of the unbraced, unbolted wall. Approximately 1,600 square feet of floor space will be freed up by the removal project.
As soon as the space is cleared, Building Manager and International Linear Collider (ILC) engineering physicist Richard Swent will begin installing prototype equipment for the ILC project. The test stands will include two modulators and two klystrons, including the Marx modulator designed and built at SLAC, and a unique "sheet-beam" klystron to be built in the Klystron and Microwave Department.
Rigging International, the contractor that worked on the Final Focus Test Beam removal project adjacent to End Station B, is using the 50-ton bridge crane inside the hall to lower 68 concrete blocks and steel shielding plates to the ground. The pieces average 15 tons each, with the heaviest at 37 tons. Conventional and Experimental Facilities is overseeing the hoisting and rigging and construction safety.
Many groups are involved in properly identifying, handling and storing radioactive materials and lead contamination, including Environment Safety & Heath's Radiation Protection and Environment Protection groups. The test accelerator in End Station B continues to run during the three-week removal project.
The 16-foot-thick wall shielded End Station B from the radiation produced in the days when the linear accelerator sent beams crashing into targets in the target room. The first particle physics experiment at SLAC used Beamline 1 in the B Target Room, where Martin Perl searched for new particles in 1966 and 1967. Over the following 15 years, a variety of experiments took advantage of the target room's three beamlines and numerous targets that produced secondary beams.
Heather Rock Woods, SLAC Today, August 10, 2007
Above image: More than 500 tons of shielding are being removed from End Station B. (Click image for larger version.)