Insertion device

The photon source of the FinEstBeAMS beamline is an Elliptically Polarizing Undulator (EPU).

Magnetic structure
95.2 mm period, 26 periods,
14 mm minimal gap, 2.475 m magnetic length, maximum magnetic field 1.13 T
DesignAPPLE II design with permanent magnets
Energy (wavelength) range
4.5 - 1300 eV
PolarizationLinear, circular and elliptical

Beamline optics

The optical layout of the FinEstBeAMS beamline is based on the plane grating monochromator illuminated with collimated light.

Collimating opticsSide cooled toroidal collimating mirror
Monochromator (cPGM)
Collimating plane grating monochromator with 2 plane gratings (92 and 600 mm/l) , internally cooled plane mirror
Focusing opticsToroidal mirrors. Focusing mirrors are used to switch the beam between branch lines by moving one or other one in front of the beam path.
Exit slitRectangular high precision slits
Re-focusing opticsSingle ellipsoidal mirror
Photon resolutionΔE/E up to 1 x 10E-4 (~2.3 meV at 10 eV, ~3.8 meV at 50 eV , ~40 meV at 400 eV)
Flux at sample (focused)10E9 - 10E13 ph/s (4.5 – 1300 eV) for E/ΔE~5000 (Maximum flux is measured around 100 eV.)
Beam size at sample

200 x 200 μm2 (horizontal x vertical), 50 x 50 μm2 when limiting exit slit and baffles
Photon flux at the end station with 400 mA ring current and a fixed 20 mm exit slit width. Black curve represents photon flux obtained with the 600 l/mm grating. Blue curve represents photon flux obtained with the 92 l/mm grating and using an appropriate filter.
Calculated photon energy resolution for (a) 600 l/mm grating and (b) 92 l/mm grating. Corresponding values of slit width are shown in the plot legend.