Focusing at BL43LXU

A. Baron, Updated February, 2020

 

High-(meV-) Resolution Spectrometer, 10m Arm

 

Bent Cylindrical Mirror (usual operating conditions)

   Beam Size:     ~ 45 x 55 mm² VxH  FWHM (Optimized)

                          ~ 60 x 60 mm² VxH  FWHM (Typical)

   Beam Divergence:      ~ 0.2 x 0.5 mrad² VxH  FWHM  (0.011 x 0.028 deg²)

   Beam Angle: ~ 3.1 mrad, up 

 

Multilayer KB ( ~50% throughput, 2+ days setup, 17.8 keV and 21.7 keV)

Beam Size:    ~ 5 x 5 mm²  FWHM  

(optimized size varies between ~4.5x4.5 and 6x7 mm² – tell staff if this difference is critical)

Beam Divergence:    ~ 5 x 7.5 mrad²  VxH 

Beam Angle:            ~ 27 mrad, up

 

Notes for the MLKB setup:

Installation needs 2+ days and must be arranged in advance -> consult beamline staff.

The setup reduces the range of angular motion of the sample in the cradle.

The setup limits the free space upstream of the sample position to ~80 mm.

Increased beam divergence will affect the spectrometer momentum resolution.

 

Compound PLEM μ-Focus (~70% throughput, ~1 day setup time – Mostly not used any more but might be possible)

    Beam Size:                  ~ 12 x 15 mm² VxH  FWHM

Beam Divergence:     ~ 1 x 2 mrad²  VxH 

   Beam Angle:               ~ 2 mrad, down

 

Notes for the PLEM (Prism Lens & Elliptical Mirror) μ-Focus setup:

Installation needs ~1 day and must be arranged in advance -> consult beamline staff.

The setup reduces the range of angular motion of the sample in the cradle.

Increased beam divergence will affect the spectrometer momentum resolution.

Tails can be an issue.

Only vertical or only horizontal focusing is possible.

 

Medium-(25 meV-) Resolution Spectrometer, 2m Arm

 

·       Beam Size:      ~ 20 x 30 mm² VxH  FWHM (Optimized)

·       Beam Divergence:   ~ 0.2 x 0.7 mrad² VxH  FWHM  (0.011 x 0.040 deg²)

·       Beam Angle:   ~ 6 mrad, up