Beamline optics

 
The beamline optic consists in a two crystals monochromator between two cylindrical parabolic mirrors in a compact arrangement , allowing high energy and Q resolution.

(PDF drawing of the Optic Hutch)

Mirrors M2 and M1

Two mirrors are used on FIP beamline for vertical focussing. They also allow to reject high order harmonics found in the white beam. Typical calculated reflectivity curves are given:

• at 3mrad grazing angle
• at 4mrad grazing angle
• at 5mrad grazing angle

Some other geometrical informations are available:

• cross section (drawing)
• 3D view (drawing)
• grazing angle of the 1st mirror
• radius of curvature of the 1st mirror
• radius of curvature of the 2nd mirror
• height of the beam on the 1st mirror

These mirrors, and the benders, are manufactures by the SESO Cnie (France). A photograph of the bender and a zoom on the actuators is available.

The vessels of both mirrors (the first and the second one) have been manufactured by IRELEC (France). The first vessel is in ultra-high vacuum, the second one in high vacuum.




Monochromator

The first crystal of the monochromator is flat and N2 cooled (see principle here). The second one (either a long one or a short one with ribs at the back side) is sagittaly bent. For geometrical reasons, the beam exit is 2cm below the source. Monochromator can use either 111 or 311 Silicon single cristals.

• With Si(111) crystals:
• altitude of the 1st crystal
• angle of the 1st crystal
• radius of curvature of the 2nd crystal
• perpendicular distance between crystals
• paralel distance between footprints on crystals
• perpendicular versus paralel distance




Monitors

• diodes monitor
• fluorescent screen
• fluorescent screen (vessel)




Vessels and beam elements

The front-end and the first vessel are in ultra-high vacuum .

• 1st vessel, from downstream (also pdf format)
• 1st vessel, from upstream
(also pdf format)
• beam limitor
• beam axis reference
• ESRF secondary vertical slits for white beam, with W jaws