New Variable Polarization VLS PGM Beamline Installed
In addition to the long straight sections that form the sides of the Aladdin "square," space exists between individual bending magnets that allow installation of one-meter long insertion devices. During the April 2009 Development week, installation of a new variable polarization, VLS PGM beamline was completed with placement of an elliptically polarized Apple II undulator (EPU) in one of these spaces in the northeast corner of Aladdin. And after several months of testing and measurements, the beamline is now available for users.
The EPU is designed to allow for the independent translation of all magnetic arrays along the beam direction. This flexibility enables operating modes providing horizontal and vertical polarization as well as left and right circular polarization. In addition, the new beamline was designed to relieve the oversubscription for User beamtime on the existing undulator PGM and has a similar spectral coverage.
The new beamline has a range of up to 250 eV with more than 2×1011 photons/sec. This flux will be delivered in a spot size of less than 200 µm × 40 µm (hor. × ver.). With a minimum magnetic gap of 17 mm and Aladdin operating at 0.8 GeV, the lowest photon energies emitted by the device when tuned to horizontally, vertically, and circularly polarized radiation are 11, 15.8, and 11.9 eV, respectively.
Why this instrument is important:
The variable polarization properties of the new beamline allow experimenters to study symmetry related properties in high Tc materials and other highly correlated electron systems. The tunability between light of opposite circular polarization opens up a completely new era for SRC researchers interested in the magnetic or chiral properties of materials in spin electronics and tailored nano structures. In addition the beamline characteristics will also be very attractive for users studying photoionization and photochemical processes in gases and biological systems.