The design and operating characteristics of the VUV undulator installed on the NSLS VUV ring are presented. Specifically, the spectral output through three circular on-axis pinholes of different diameters has been measured. Near the minimum magnetic gap (40 mm), the flux into a 0.25 mrad circular aperture at the peak of the fundamental (hv = 57 eV) is ≈ 1 × 1014 photons/(s·0.1 A·1% bandwidth). We find good agreement in spectral shape between these measured spectra and spectra calculated by integrating the theoretical undulator emission over the relevant spatial variables and including electron beam emittance. We also show calculated zero-emittance and on-axis flux spectra for comparison. A description is given of the beam line and monochromator currently installed on this undulator for the purpose of performing spin-resolved photoemission.
ASJC Scopus subject areas
- Nuclear and High Energy Physics