Beamline Optics
Hippie is a soft X-ray beamline designed to deliver high-intensity photon flux (>1012 ph/s) with exceptional resolution by fully utilising the very low emittance of the 3 GeV ring.
Main Beamline Parameters
| Energy Range | 250 eV - 2200 eV |
| Polarisation | Horizontal |
| Resolution | up to 35000 |
| Photon Flux | > 1012 ph/s |
| Spot Size | 60 µm (h) x 25 µm (v) |
The HIPPIE beamline can achieve 25000-35000 resolving power at 5-10 µ slit size. HIPPIE’s beamline flux is higher than 1012 ph/s up to 1800 eV with 50 micron exit slits, typical for AP-XPS measurements, where the resolving power is ~10000.
-
- HIPPIE resolving power at 867 eV
-
- HIPPIE resolving power at 867 eV
X-Ray Source
| Type | APPLE II with permanent magnets |
| Period Length | 53 mm |
| Physical Length | 4 m (placed inside 5m straight section) |
| Accessible Polarisations | Linear (inc. Horizontal), Elliptical, Circular |
Beamline Optics
| M1 | M2 | PG | M3 | Slit | M4 | |
| Shape | Toroid | Plane | Plane | Cylinder | Rectangular | Toroid |
| Deflection | Horizontal (to ring) | Vertical (up) | Vertical (down) | Horizontal (away from ring) | - | Horizontal (away from ring) |
| Distance, m | 24 | Variable | 26 | 27 | 39 | 47 |
| Incidence Angle | 1° | 0° - 9° | 0° - 12° | 1.5° | - | 1.5° |
| Optical Size, mm | 320 x 10 | 370x10 | 130 x 10 | 120x28 | - | 130x20 |
| Material | Si | Si | Si | Si | - | Si |
| Coating | Au | Au | Au | Au | - | Au |
| Roughness, Å | 3 | 3 | 3 | 3 | - | 3 |
The beamline uses a Collimated Plane Grating Monochromator (cPGM), a monochromator type which was developed at BESSY. Currently only one branchline (AP-XPS) is planned to be build. However, it will be possible to build a second branchline by inserting another focusing mirror in the beam path. The other branch will then only need a refocusing mirror, since its exit slit and vacuum components are already installed.
The first optical element (M1) in the beamline is a toroidal mirror, which collimates the beam vertically and focuses the beam horizontally onto the exit slit. The cPGM consists of a plane mirror and one or more plane gratings. The dispersed radiation from the grating is focused horizontally onto the exit slit by the cylindrical focusing mirror (M3). The refocusing for the AP-XPS branch is accomplished by a single toroidal mirror (M4) with tangential and sagittal exit arms of 2 m and 2.060 m, respectively. In this way, the mirror does not image the vertical opening of the exit slit directly, but the vertical image size at the sample plane (2 m from M4) is dictated by the vertical divergence of the beam, which can be controlled by the monochromator. All the mirrors, except for the plane mirror in the monochromator, deflect horizontally – hence, all slope errors and heat load deformations on these mirrors are diminished in the dispersion plane in a well-known manner.
For more detailed discussion of EPU53 and beamline optics, please see following documents
HIPPIE Appendix C – Report Rami Sankari