Machine and Optics Hutch

last modified 14-10-2008 16:26

The optics hutch is common for the ID10A and ID10B lines. Therefore it is of highest priority NOT to touch anything upstream of the SS0 slits during operation as it might affect the experiment carried out at ID10B.

From the undulator source the beam encounters the following optical elements on its way towards the final beamstop in the TROIKA III hutch :

Undulators - Be lens/Front end - Primary slits - ID10B 1st monochromator - SS0 slits - Double mirror (thermal bender) - TROIKA I photon absorber/beam shutter - SS1 slits - TROIKA I monochromator - SS2 Slits - TROIKA III monochromator - TROIKA III beam shutter (SCHEMATIC DRAWING)

Here follows a short description of the above mentioned elements:

Undulators

U27, U35 and U27/U35 revolver unit. Technical details can be found in Beamline Description (UNDULATOR SOURCE). The undulators are controlled by the ID application "idappli" running on the UNIX workstation tina.esrf.fr. Usually this application is visible on the terminal screen TROIKA23 placed on top of the NIM module in the control hutch. In the ID application the undulator gaps are set and by choosing “automatic mode” the undulators will return to these values after an eventual opening due to beamloss etc. Not that the automatic mode expires after 72 hours 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 described in the ALIGNMENT GUIDE.

Berylium lenses

A guide to the alignment of the lenses can be found in the ALIGNMENT GUIDE. The lens position can only be changed by the local contact (staff member) and upon agreement with ID10B.

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 (short description in the ALIGNMENT GUIDE).

ID10B monochromator

Belongs to ID10B and cannot be controlled from our side. The monochromator is a semi transparent diamond crystal with approximately 30% absorption. When operated correctly :-) it does not affect the ID10A beamline.

SS0 slits

The SS0 slits is the first optical component that can be operated without influence on the ID10B line. It is often used together with the SS1 slit (see later) as a collimator to define the beam size. A small beam size reduces the heat load on the monochromator (important!). Users should never touch SS0 unless a clear agreement has been made with the local contact. The SS0 slit is operated under SPEC which is the control language of the beamline (ON-LINE SPEC MANUAL). SS0 consists of four slit blades that can be operated independently. The SPEC command

mv s0vg 0.1

moves (mv) the vertical gap (vg) of SS0 to 0.1 mm. The SPEC command

mvr s0vo 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

ws0

will display the current settings of the slit.

Double mirror

The double mirror (thermal bender) is currently under re-commissioning and controlled by its own SPEC version HX. See the ALIGNMENT GUIDE for details.

Photon absorbers

Can only be operated by the beamline staff. This device is normally not touched during an experiment.

TROIKA I Beam shutter

The TROIKA I beam shutter allows you to enter the experimental hutch without being irradiated (very convenient) and is a main part of the personnel safety system (PSS) at the beamline. The beam shutter is operated by SPEC with the self-explanatory commands "shclose" and "shopen". The hutch door is locked automatically before the shutter can be opened. This safety procedure you will learn more about in the mandatory SAFETY TRAINING for users.

SS1 slits

Same as SS0 slits (see above). The SS1 slit is the last component the beam meets before the Troika I monochromator, approximately 43 meters from the undulator source.

TROIKA I monochromator

The TROIKA I MONOCHROMATOR is a multi crystal mono operating in horizontal scattering geometry where four different crystals can be inserted in the beam (ALIGNMENT GUIDE). The most commonly used are Si(111) and C(220). The crystal can be rotated about an axis perpendicular to the beam. This is done in SPEC by typing

mv mono 14.5

which will rotate the monochromator to 14.5 degrees. This means that the white beam hits the crystal surface under an angle of 14.5 degrees and consequently monochromatic radiation will be diffracted according to Bragg’s law. Find more details in Beamline Description (The Troika I Monochromator). This monocromator delivers monochromatic beam to the experiments carried out in the TROIKA I expeimental hutch (EH1).

SS2 slits

The SS2 slit is situated in the small TROIKA III optics hutch (OH2) and is the last component the beam meets before the TROIKA III monochromator, approximately 57 meters from the undulator source. These slits (and the rest of the Troika III equipment) are controlled by the SPEC application "optics" running on the Linux PC tind.esrf.fr in the TROIKA III control hutch.

TROIKA III monochromator

The TROIKA III monochromator is a channel cut Si (111) crystal and is operational between 6 and 22 keV. It delivers monochromatic beam to the experiments carried out in the TROIKA III experimental hutch (EH3). The monochromator is operated via the spec application "optics" by use of the usual spec commands (motorname mono). This application is running on the tind.esrf.fr Linux PC in the TROIKA III experimental hutch. If not, it may be started by typing

optics

in the unix prompt. The motor mpiezo may be scanned from time to time to recover the intensity scattered from the monochromator. Alternatively the macro

piezocheck

may be launched from "optics". From "optics" the usual spec commands may also be used to drive the slit modules SS0, SS1 and SS2 as described above.

TROIKA III beam shutter

The TROIKA III beamshutter approximately 57.5 m from the beam may be operated by the "optics" commands

shopen id10c_eh3

and

shclose id10c_eh3

This allows access to the TROIKA III experimental hutch. The shutter in the TROIKA I experimental hutch exit may also be operated (takes the beam off the TROIKA III mono) with

shopen id10c_oh2

and

shclose id10c_oh2