[undulators , front end , primary slits , White beam double mirror , Channel cut monochromator , White beam transfocator , Monochromatic beam double mirror , optics slit , Monochromatic beam transfocator , beam shutter ]

The optics hutch OH1 is common for the ID10-EH1 and ID10-EH2 end stations.

From the undulator source the beam encounters the following optical elements on its way towards the ID10-EH1 beam shutter :

Undulators - Front end - Primary slits - White beam double mirror - Channel cut monochromator - Secondary slits - White beam transfocator - Monochromatic beam double mirror - Optics slits - Monochromatic beam transfocator - ID10-EH1 beam shutter. (SCHEMATIC DRAWING and Detailed Layout of the Optics)

ID10_OH1_OH2_EH1.png

Here follows a short description of the above mentioned elements:

 

Undulators

The ID10 beamline is equipped with U27, U35 and U27/U35 revolver unit. Technical details can be found in Beamline Overview (undulators). The undulators are controlled by the ID application "idappli" that can be started in any X-terminal at MAX workstation. ID10 workstations are computers with the Linux operation system. In the ID application the undulator gaps are set and by choosing “automatic mode” the undulators will return to these values after being closed at refills etc. Note that the automatic mode expires after 144hrs after which the front end will close i.e. the beam is blocked. DO NOT CHANGE THE UNDULATOR GAPS ONCE THEY'VE BEEN SET! SPEC macros to calculate the undulator gap for a given energy are either u27_energy , u27_gap and u27_harmonic or u35_energy , u35_gap and u35_harmonic.

 

Front end

Contains photon absorbers (heat load filters) and the main beam shutter. The front end also marks the transition from the machine to the beamline.

 

Primary slits

Primary slits are the high heat load water cooled slits located at the beginning of the OH1 hutch. Conventional setting of the fully opened primary slits are 0.5 mm vertical gap and 1.0 mm horizontal gap.

 

The White Beam Double Mirror

The white beam double mirror (WBDM) is the first optical element of the ID10 beamline. It is a water cooled device. It works in the horizontal reflection geometry. The horizontal reflection provides stability and better coherence preservation. The ultra-rigid mount limits the range of the grazing angle from 2.6 to 3.6mrad. Two mirrors are separated by a fixed gap of 1.6mm. To have flexibility in the band pass filtering up to 30keV there are three reflecting surfaces on a silicon body: a central stripe with bare silicon (Si) and two lateral stripes coated with Platinum (Pt) and Palladium (Pd). The grazing angle of 2.6mrad provides energy cut-offs at ~11keV (Si) and ~23keV (Pd). Operating in the range between 2.6 and 3.6mrad allows the third harmonic rejection to be better than 10-5 in the energy range 7-12keV and 14-30keV

 

Channel cut monochromator

Channel cut monochromator (CCM) is a liquid nitrogen cooled monochromator with two sets of crystals working in symmetric Bragg-Bragg reflection which provide monochromatic beam in the energy range 7-30 keV. Optionally could be used either with Si(111) reflection to cover energy range 7keV - 25 keV or with Si(311) reflection to operate in the range of 14 keV - 30 keV. Find more details in Beamline Overview (monochromator).

 

Secondary Slits

Secondary slits as the primary slits are the high heat load water cooled slits located after CCM in the OH1 hutch.

 

The White Beam Transfocator

The white-beam transfocator (WBTF) is the first focusing device at ID10 positioned at 36m from the source. It consists of a series of nine pneumatic actuators (with in-out position) mounted in a 1m long UHV vessel carrying a 2n number of Be compound refractive lenses (CRLs) with 300mm radius of curvature. Each individual lens holder is water cooled. The first slot is only a pinhole to limit the power load on the subsequent sets. The 300mm Be CRLs sets in number 2n, n=1,2,4,8,16,32, occupy six slots from slot n.3, while slot n. 2 and the last slot n. 9 carry a linear lens and one 200mm Be CRL, respectively. This last lens focuses 7keV X-rays at the ID10-CS station. This system allows us to adjust the focal spot size from half a millimetre down to a few micrometers in a large energy range in EH1 and EH2 by selecting the appropriate number of lenses (up to 63 lenses).

 

Monochromatic beam double mirror

The double mirror consists of two flat mirrors that reflect in vertical plane and serve to deflect the beam from horizontal plane to the liquid surface and to cut off higher harmonics in absence of the white beam bouble mirror. Each mirror has three stripes: Pt, Pd, and bare substrate (Si). Choice of a stripe depends on energy and incident angle on a sample.

 

Optics slit (os)

Optics slit is the optical element in the OH2 hutch which is located after monochromatic beam double mirror in front of the monochromatic beam transfocator at the distance of 4.2 m from the center of rotations of the goniometer (= sample position) and at 40.8 meters from the undulator source. Optics slit (os) is often used together with the s0 slit (located in experimental hutch) for the beam collimation. Another purpose of os is to clean up the beam after the mirror. The os slit is operated under SPEC application eh1_exp (on-line SPEC manual). os consists of four slit blades which can be operated independently. The bottom blade of the os is equipped with an additional beamstop in order to stop high-energy spill-over of the first mirror. The SPEC command

mv osvg 0.1

moves (mv) the vertical gap (vg) of os to 0.1 mm. The SPEC command

mvr osvo 0.1

moves relative (mvr) the vertical offset (vo) by 0.1 mm. The equivalents in horizontal are of course named hg and ho. The command

wos

will display the status of the slit.

 

The Monochromatic Beam Transfocator

The monochromatic-beam transfocator (WBTF) is the first focusing device at ID10 positioned at 41.3m from the source. It consists of a series of nine pneumatic actuators (with in-out position) mounted in UHV vessel carrying a 2n number of Be compound refractive lenses (CRLs) with 200mm radius of curvature. Lens holders are not cooled and can operate only in monochromatic beam. The first and tha last slots have only a pinhole for alignmnet puposes. The 200mm Be CRLs sets in number 2n, n=1,2,4,8,16,9, occupy six slots from slot n.2. This system allows to adjust the focal spot size from half a millimetre down to 4 micrometers in a large energy range in EH1by selecting the appropriate number of lenses (up to 40 lenses).

 

Beam shutter

The ID10-EH1 beam shutter allows you to enter the experimental hutch without being irradiated (very convenient). The beam shutter is operated by SPEC with the self-explanatory commands shclose and shopen. The hutch door is locked automatically when the shutter is opened. This you will learn more about in the mandatory safety training for users.