Machine and Optics Hutch

[undulators , Be lenses , front end , primary slits , ID10B mono , double mirror , optics slit , beam shutter ]

The optics hutch is common for the ID10B and ID10A lines. Therefore it is of highest priority NOT to touch anything upstream of the 1st ID10B monochromator during operation as it might affect the experiment carried out at ID10A.

From the undulator source the beam encounters the following optical elements on its way towards the ID10B beam shutter :

Undulators - Be lens - Front end - Primary slits - ID10B 1st monochromator - ID10B 2nd monochromator - Guard slits - Double mirror - Secondary (optics) slits - ID10B beam shutter. (SCHEMATIC DRAWING and Detailed Layout of the Optics)

Here follows a short description of the above mentioned elements:

Undulators

The Troika 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 MAXPC (ID10B workstation with 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 72hrs 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.

Berylium lenses (facultative information)

ID10A has a set of Be lenses that focus the X-ray beam in vertical plane in ID10A experimental hutch. If a Be lens is used at ID10A then some of the experiments going at ID10B can benefit from the focusing having the beam size on the sample position about 50 microns. Note that any manipulation with lenses when the optics of ID10B is already aligned may cause changes in alignment at ID10B. Modification of lenses position during ongoing experiment at ID10B should be done by ID10A local contact (staff member) only after informing ID10B local contact and/or Users and achieved agreement. More information about Be lenses is on ID10A, Machine and Optics Hutch page.

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

In general the primary slits are not touched during normal operation. However, after each shutdown they are realigned from ID10A workstation. Conventional setting of the primary slits are 0.5 mm vertical gap and 1.0 mm horizontal gap.

ID10B monochromator

Belongs to ID10B and is controlled with the optics application running on the ID10B workstation. Operation with the first monochromator is allowed only to staff members. Wrong operation can damage the first monochromator and can affect on experiments running at ID10A !!! The first monochromator is a semi transparent diamond crystal with approximately 30% absorption. The second monochromator crystal allows to work at fixed exit geometry for the goniometer in the experimental hutch. Available exit aperture after first monocromator and travel range of the second monochromator crystal result in the energy tunability at ID10B in the range from 8 keV to 13 keV. Users are allowed to tune the 2nd monochromator to restore the flux on the sample. Two motors are to be used: mono2 - Bragg angle and chim2 - tilt of the 2nd monochromator. Both motors are controled with the optics application.

The ID10B monochromator is a double crystal monochromator where pair of diamond crystals work in symmetrical Bragg-Bragg geometry and separated by a distance between 1.18 m and 2.0 m (depend on chosen energy). Optionally could be used either pair of diamonds (111) to cover energy range 8keV - 13 keV or pair of diamonds (220) to operate in the range of 13 keV - 22 keV. Find more details in Beamline Overview (monochromator).

Guard slits (ops)

Guard slits are the set of two blades that move in vertical plane.

Double mirror

The double mirror consists of two flat mirrors that reflect in vertical plane and serve to cut off higher harmonics and deflect the beam from horizontal plane. 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 last optical element in the optics hutch and located in front of the Beam shutter at the distance of 2.508 m from the center of rotations of the goniometer (= sample position) and at 38.377 meters from the undulator source. Optics slit (os) is often used together with the s0 slit (located in experimental hutch) as a collimator to define the beam size. Another purpose of os is to clean up the beam after the mirror. The os slit is operated under SPEC which is the control language of the beamline (on-line SPEC manual). os consists of four slit blades that 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

mvr osvo 0.1

wos

Beam shutter

The ID10B 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.