The Atomic Physics Beamline at ATLAS is used for a variety of experiments which study the atomic and molecular physics. Three experimental stations are available. At present, one of these is used for measuring lifetimes of highly charged ions, one is used for ultraviolet spectroscopy measurements, and the third is used for polarization measurements. The configuration of the beamline is changed periodically to accommodate new experiments and the beamline is generally reconfigured for an experiment in the weeks preceding a run. The experiments employ thin carbon foils or vapor targets. Figure 1 is a layout of the beamline showing the three experimental areas. Figure 2 shows a more detailed view of the Grazing Incidence Monochrometer and the polarization experiment. Various spectrometers are available including an array of three Si(Li) x-ray detectors, normal and grazing incidence UV spectrometers fitted with position sensitive detectors, and a time-of-flight mass spectrometer.
The beamline has two quadrupole doublets which can be used singly or in combination to focus the beams from ATLAS on target. The first doublet is located 3.89 m from the center of the superconducting switching magnet and the other is located 6.67 m from the center of the magnet. Two xy steerers are available. One is located upstream of the first quadrupole and the other is located downstream of the second quadrupole. A set of remotely operated 2-jaw slits for controlling the horizontal divergence of the beam is located 1.76 meters from the cneter of the switching magnet. There is a diagnostics ladder located just upstream of the lifetime experiment. This contains a ruby quartz which can be viewed via a TV camera, and three isolated collimators. The four components on the ladder can be remotely positioned. Other diagnostic elements include three beam profile monitors, four Faraday cups, and a fast-Faraday-cup. The latter can be used to set up beam bunching or debunching. There is also a capability for mounting foils just upstream of the superconducting magnet. This allows one to strip the beam from ATLAS and select a specific charge state to be directed to target.
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