U41_PGM

U41_PGM is a microfocus beamline with flexible end stations. It provides high photon flux and small focus size in soft x-ray range.

U41 undulator delivers the highest brilliance photon beam (with horizontal linear polarization) among Bessy's undulators. It has 77 magnet units with period length 41.2 mm. The smallest undulator gap is 15.5 mm.

Optical layout

Photon flux as a function of photon energy

Photon flux as a function of photon energy and fixfocus constant cff. (white area: out of the mirror and/or grating limits)

Resolving power at nitrogen K-egde, exit slit 20 μm, 600 l/mm grating

Focus spot at exit slit 40 μm

Beamline data
Location	13.2
Source	U41
Monochromator	PGM
Energy range	170 - 1800 eV
Energy resolution	> 2000
Flux	10¹³
Polarisation	horizontal
Divergence horizontal	1.2 mrad
Divergence vertical	0.5 - 2.5 mrad
Focus size (hor. x vert.)	23 μm (hor.) x 12 μm (ver.), (FWHM, exit slit 40 μm)
Distance Focus/last valve	475 mm
Height Focus/floor level	1376 mm
Free photon beam available	yes
Fixed end station	no
premonochromator optics	M1: toroidal mirror, horizontal deflection, 2Θ=176°, gold coated, water cooled, vertical collimation, horizontal focusing onto exit slit
monochromator	Principle: plane grating monochromator with collimated light, operated at negative diffraction order (cff < 1) Optical components: G1: plane gratings, 600 l/mm, blaze 0.8°, vertical deflection, 2Θ=169-175°, gold coated, water cooled M2: plane mirror, vertical deflection, 2Θ=169-175°, gold coated, water cooled
focusing mirror	M3: cylindrical mirror, horizontal deflection, 2Θ=176°, gold coated, vertical focusing onto exit slit
exit slit	slit settings: 20/40/100/200/500/2000/3000 μm ± 200 mm translation
postmonochromator optics	M4: toroidal mirror, horizontal deflection, 2Θ=176°, gold coated, vertical and horizontal demagnification of exit slit into sample area
references	[1] R. Follath, F. Senf, Nucl. Instr. Meth. vol. A390 (1997) 388-394. [2] M.R. Weiß, R. Follath, F. Senf, W. Gudat, J. Electr. Spectrosc. Relat. Phenom. vol. 101-103 (1999) 1003-1012. [3] Ch. Jung et al., Proceedings SRI 2000.

Useful information for users connecting end station to beamline:

The last valve at the end of the beamline is a window valve with DN 63 CF flange. A bellow is required for connection of end station to beamline in order to relieve any possible stress on refocusing chamber imposed by end station. The window valve can only be open when the pressure at the end station side is in 10^-9 mbar range (interlock protected, bypassing the interlock is prohibited). Oil pump is not allowed when connected to beamline.

Beamline provides 220V and 380V electrical power for users. Cooling water (30°/40°, 10 bar/2 bar), pressurized air (8 bar), oil free exhausting lines, helium recycle system and internet connection (cable and wireless) are also available for users.

For further information, please contact beamline scientist.