Overview of basic parameters:
Undulator: EPU61 with 41.5 periods and a period length of 61 mm.
Energy range: 30-1500 eV
Polarization models: Linear polarizations: horizontal and vertical. Circular polarizations positive and negative. Different polarization modes have slightly varying energy range.
Gratings: Place for 3 gratings. Initially one Au coated 1221 lines/mm and one Ni coated 250 lines/mm gratings are installed. The Ni coated grating offers higher flux in the 200-600 eV range at the expense of resolving power
Energy resolution: Up to R = 10 000. Typically R = 5 000 provided for users
Flux: 10^13 to 10^10 photons/s
Beam spot size: 100 µm x 100 µm at APXPS branch, 5 µm x 25 µm at RIXS branch
Beamline flux curve measured on the APXPS branch BPM diode:
Downloadable beamline flux files (text files):
New flux (after 2026-06-30)
Beamline_flux_1221 (Measured with 1221 l/mm grating)
Beamline_flux_900 (Measured with 900 l/mm grating)
Cell_flux_1221 (Measured inside the APXPS cell with 1221 l/mm grating)
Cell_flux_900 (Measured inside the APXPS cell with 900 l/mm grating)
Old flux (before 2026-06-30)
Beamline flux
Beamline flux (as measured in AP cell)
Approximate beamline resolution measured with different gases in the beamline gas absorption cell:
| Mirror - M1 | Mirror - M2 | Grating 2 | Grating 3 | Mirror - M3 (RIXS) | Mirror - M3 (APXPS) | Mirror - M4 (RIXS) | Mirror - M4 (APXPS) | |
|---|---|---|---|---|---|---|---|---|
| Shape | Cylindrical | Plane | Plane | Plane | Toroidal | Toroidal | Elliptical | Toroidal |
| Deflection | Horizontal (towards ring) | Vertical (up) | Vertical (down) | Vertical (down) | Horizontal (towards ring) | Horizontal (away from ring) | Horizontal (towards ring) | Horizontal (away from ring) |
| Size (h x v) mm^2 | 210x20 | 520x50 | 120x40 | 120x40 | 240x30 | 230x30 | 250x40 | 250x40 |
| Clear aperture | 170x15 | 500x20 | 110x30 | 110x30 | 220x20 | 220x20 | 240x20 | 240x20 |
| Coating | Au | Au | Au | Au | Au | Au | Au | Au |
| Slope error (arc sec) | 1/0.3 | 0.1/0.1 | 0.1/0.1 | 0.1/0.1 | 1/0.3 | 1/0.3 | 5/1 | 1/0.3 |
| Entrance arm (mm) | 12000/- | infinity/15300 | infinity/15300 | 11300 | 4500/infinity | |||
| Exit arm (mm) | infinity/- | 7000/7500 | 7000/infinity | 700 | 1562/1500 | |||
| Groove density | 1221 | 900 | ||||||
| Blaze angle | 1.7 | 0.9 |