Experimental Hutch

The experimental hutch is the safety hutch where the experiment will take place. Because of the strong X-ray beam, this hutch is automatically locked during operation for safety reasons. The hutch must be searched and closed before the beam is available. This procedure is the main topic of the SAFETY TRAINING COURSE that must be followed by all ESRF users prior to the start of their experiment.

At ID10 there are two experimental hutches, EH1 and EH2 served by two different monochromators. They are described in the Machine and Optics hutch section. The main component of an experimental hutch is the diffractometer, including various motorized translations and rotations to be able to control your experiment.

All motor names are controlled by spec, the beamline operations system which is running on the ting.esrf.fr linux workstation. Usually the spec version used is eh2_exp (sixcircle) and it can be started simply by clicking an icon on the desktop. (A spec guide is available).

The EH2 Diffractometer

The TEH2 diffractometer is described in the Beamline Description (EH2 Instrumentation). The local contact will align the beamline and diffractometer for you at the beginning of the experiment. The diffractometer has about 15 motors that can be operated independently from SIXC, here we will only describe the most commonly used ones. For more details ask your local contact.

EH2 Motors

All diffractometer motors can be moved by the spec command

mv motorname x

This moves (mv) the motor to the position x. motorname is often a two or three letter name. The units of x is mm for translational motors while it is degrees for rotations. The sign of the motors follows a right hand coordinate system where the x-axis is along the beam direction and the z-axis is vertical, positive up (deviations from this rule unfortunately exists). The command "mvr" will move relative to the current motorposition. The motorposition is displayed by typing

wm motorname

Here follows a description of the most important motors of the EH2 hutch and their functions.

Motorname	Function
z0, z1 and z2	Height of the three towers (elevator stages) of the first granite table. These towers carry local mirrors by which higher order X-rays can be suppressed. The beam pipes are under high vacuum.
r0, r1 and r2	Rotation of the above mentioned elements.
y1,y2 and y3	Horizontal translation of the local mirrors and the X95 profile holding the beam defining slits.
cshg,csho,csvg,csho	Control of the first roller blade slits CS. cshg and csvg are the horizontal- and vertical gaps while csho and csho are the horizontal and vertical offsets. These slits are used to select the coherent part of the beam. The maximum opening is 4 mm.
rghg,rgho,rgvg,rgho	Control of the second roller blade slits RG. rghg and rgvg are the horizontal- and vertical gaps while rgho and rgho are the horizontal and vertical offsets. These slits are used to suppress Fraunhofer diffraction from the CS or to select the coherent part of the beam. The maximum opening is 4 mm.
sghg,sgho,sgvg,sgho	Control of the guard slits SG. sghg and sgvg are the horizontal- and vertical gaps while sgho and sgho are the horizontal and vertical offsets. These slits are used to suppress Fraunhofer diffraction from the CS or RG. The maximum opening is 4 mm.
th	This is the rotation of the sample table which is a standard Huber goniometer head.
phi and chi	Tilts of the goniometer head
ys and xs	Horizontal translations of the goniometer perpendicular and parallel to the beam
jdz	Vertical translation of the diffractometer
z3 and r3	Height and rotation (in the vertical plane) of the additional flightpath carrying the detector stage on the del arm. This flightpath is usually a standard X95 aluminum piece with length ranging from 0.5 m to 2m.
del	Rotation in the horizontal plane of the flight path carrying the detector.
rgh and rgv	horizontal- and vertical gap of the pre-detector slit
rx and rz	horizontal and vertical translation of the pre-detector slit.

Several other motors might be of interest depending on the actual experimental set-up.

A motor is controlled by SPEC through the IcePAP motor drives situated in the large blue racks in the control hutch. It is important NOT TO DISCONNECT ANY MOTOR CABLES without disabling motor in the IcePAP rack. In general, modifications of the motors and IcePAPs can only be carried out by the beamline staff.

Attenuators

Attenuators are installed before the beam defining slits. The attenuators are operated by the command "att x" where x is a number between 0 and 15. The command "att 0" takes out all attenuators. The status of the attenuator is displayed by typing "att" or by looking at the controller in the NIM rack. The attenuators consist of thin metal foils and is calibrated at 8keV so the attenuation roughly follows 10^x/2.

Monitor detector

A monitor detector is installed after the beam defining slits. This enables the measurement of the incident beam intensity by typing "ct". The monitor registers the photons scattered from a Kapton foil and the command "eff" calculates the scattering efficiency. The command "eff 8 40 1 0.08" will calculate the efficiency at 8 keV when the distance from the monitor to the Kapton foil is 40mm with a monitor aperture of 1mm and a Kapton foil thickness of 0.08 mm. Different apertures and Kapton foils are available at the beamline. For details about detectors in general, see below.

Detectors and Correlators

BICRON scintillator counter Model 1XM.040B, PMT type R580, with beryllium entrance window.

Crystal size: 1" x 1mm; PMT size: 1.5"; Energy range: 3 to 100 keV; Resolution: 30%; Count rate range: 0-30000 cts/sec.

Two types of 2D cameras are available : A deep depletion Andor Ikon-M camera that is used in direct illumination mode to be able to do single photon counting for XPCS applications. The camera has 1024 x 1024 pixels and a pixel size of 13 µm. In addition a Maxipix 2x2 pixel array detector is available. It has 516x516 pixels with 55 µm pixel size and can run a 300 frames/s speed. Both detectors are radiation sensitive and must be used carefully to avoid overexposure and subsiquent damage.

For X-ray Photon Correlation Spectroscopy (XPCS), two correlators are available:

1. Internal correlator: ALV5000\E, a multiple tau digital Correlator, for single or dual auto-correlation and cross-correlation, 200 ns sampling time and up to 288 Multiple Tau channels.

2. External correlator: Flex01D-08, fast high resolution multiple tau digital correlator, with 8ns minimum sample time and 1088 real time channels.

Helium

Some of the flightpaths are filled with He (from the big pressurized bottle at the wall). It is important to check the He flow from time to time.

Other Equipment at EH2

The experimental hutch is equipped with a lot of additional hardware. Surely you will use different pumps(turbo/molecular pump or membrane pump) during your experiment but also other devices such as displex cryostats and a Small Angle X-ray Scattering(SAXS) chamber are available. For information about specialized equipment not described here, ask your local contact.

EH2 Experimental Hutch

The EH2 experimental hutch comprises an almost stationary setup optimized for coherent SAXS/WAXS experiments. The main features are two granite tables with the optics and the diffractometer and an optical table carrying the detector assembly. More details about the EH2 station (includinc SPEC motornames) can be found in the Beamline Description (EH2 Station).