Advanced Photon Source

An Office of Science National User Facility

Experiment Hall & Beamlines

The ratchet-shaped radiation-shielding wall between the APS storage ring and the experiment hall serves as a line of demarcation. Thirty-five "sectors" are marked on the experiment hall floor. Each of these sectors comprises at least two x-ray beamlines, one originating at a bending magnet in the storage ring lattice, the other at an insertion device. With all APS sectors equipped and operating, the APS, in effect, has 35 discrete laboratories under one roof. More information about APS beamlines, including maps and specifications, are available at Find a Beamline.
Experiment hall empty (left) and with an instrumented sector (right)
The circular APS experiment hall is where scientists assemble their experimental apparatus and carry out research. The hall has been designed as an enclosed, 1104-m-circumference optical bench. The hall floor is made of 1-ft-thick poured concrete. Usual practice in poured concrete construction is the use of evenly spaced cuts in the slab to create isolated sections, which are free to move independently, alleviating cracks. There are no cuts in the APS experiment hall floor, creating a solid and uniform slab, as shown in the photo below, which was taken before installation of experimental equipment.
A stable experiment hall floor is of great benefit to users of the APS, who must align their experimental equipment to submicron tolerances. Regular surveys of the floor show that it has moved at most by 6 mm in certain areas (less in others) and is now moving on the scale of 0.2 mm per year. That figure includes shrinkage, settlement, and all of the transitory effects experienced by concrete over time.

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