Rapidly modulated variable-polarization crossed-undulator source

Abstract

An integrated system to produce and utilize variable-polarization radiation from a crossed undulator source on the Aladdin storage ring is being designed in a multilaboratory collaboration. Brief discussions of the motivation and options available precede a description of the source. Comments on ongoing work are also presented.

Circular Dichroism Using Synchrotron Radiation

“…The preference of designers to keep the median plane free of such magnetic structures (and hence separate from the vacuum components) has led to several innovative arrangements in which effective helical symmetry is produced by arrays of magnets located entirely above and below the vacuum chamber of the ring (Elleaume, 1990(Elleaume, , 1994Diviacco and Walker, 1990;Elleaume et al, 1991;Carr and Lidia, 1993;Sasaki et al, 1993;Lidia and Carr, 1994;Goulon et al, 1995;Carr et al, 1995). Circularly polarized light can be produced in asymmetric undulators (Goulon et al, 1987;Pfluger and Heintze, 1990), or designs in which the photon beams from two sequential insertion devices (crossed undulators) are combined (Moissev et al, 1978;Kim, 1984;Bahrdt et al, 1992;Green et al, 1992). The latter devices offer the possibility of fast switching of the polarization.…”