The Nanoscience Beamline at Diamond, Optical Design Considerations

Journal Article · Fri Jan 19 04:00:00 EST 2007 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2436124· OSTI ID:21052580

Reininger, Ruben ^[1]; Dhesi, Sarnjeet ^[2]

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1. Scientific Answers and Solutions, 5708 Restal St., Madison, WI 53711 (United States)
2. Diamond Light Source, Chilton, Didcot, Oxfordshire, OX11 0DE (United Kingdom)

The main requirement of the Nanoscience Beamline at Diamond is to deliver the highest possible flux at the sample position of a PEEM with a resolving power of about 5000 in the energy range 80-2000 eV. The source of the beamline is a couple of APPLE II helical undulators in tandem that can also be used separately to allow for faster switching of the circular polarization. Based on its versatility, a collimated plane grating monochromator using sagittally focusing elements was chosen to cover the required energy range with three gratings. The operation of this monochromator requires a collimated beam incident on the grating along the dispersion direction. This can be achieved either with a toroid, focusing with its major radius along the non-dispersive direction at the exit slit, or with a sagittal cylinder. The former option uses a sagittal cylinder after the grating to focus the collimated beam at the exit slit. In the latter case, a toroid after the grating is used to focus in both directions at the exit slit. The advantage of the toroid downstream the grating is the higher horizontal demagnification. This configuration fulfills the Nanoscience Beamline's required resolving power but cannot be used to achieve very high resolution due to the astigmatic coma aberration of the toroidal mirror. The focusing at the sample position is performed with a KB pair of plane elliptical mirrors. Assuming achievable values for the errors on all the optical surfaces, the expected spots FWHW in the horizontal and vertical directions are 10 {mu}m and 3 {mu}m, respectively. The calculated photon flux at this spot at 5000 resolving power is >1012 photons/sec between 80 and 1600 eV for linearly polarized light and between 106 and 1200 eV for circularly polarized light. The beamline is expected to be operational in January 2007.

• OSTI ID: 21052580
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 879; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BEAM PRODUCTION
DESIGN
DIFFRACTION GRATINGS
EMISSION SPECTROSCOPY
EV RANGE
MIRRORS
MONOCHROMATORS
NANOSTRUCTURES
OPERATION
PHOTOELECTRON SPECTROSCOPY
PHOTON BEAMS
POLARIZATION
POLARIZED BEAMS
RESOLUTION
WIGGLER MAGNETS
X RADIATION