[ M_R_C_A_T ] MRCAT Instrumentation

The MRCAT Insertion Device line is fully operational and is used primarily for spectroscopy and fluorescence mapping experiments. The Bending Magnet line is fully operational and is available for spectroscopy, photochemistry, and high energy tomography.


Insertion Device Line

Wide Energy Range Monochromator

We currently have a Si (111) monochromator consisting of a cryo-cooled first crystal designed by the IIT Center for Synchrotron Radiation Research and Instrumentation (CSRRI) and a 250mm long second crystal which provides an energy range of 4.8keV to 30keV from the fundamental reflection. Both crystals have been chemically polished and have been measured to deliver the theoretical photon flux to the experimental station. The second crystal has a piezoelectric tuning actuator with a.c. feedback and a Bragg-normal motion which permits some degree of fixed-offset operation. In combination with the multichannel scaler electronics described below, we are able to take complete EXAFS scans of 1000eV in under 1 min.

Harmonic Rejection and Steering Mirrors

The MRCAT beamline has a 60cm long flat harmonic rejection mirror with Pt and Rh coatings. This mirror resides in the experimental station and may be moved vertically in or out of the beam as the experiment requires.

Microfocusing

Basic microfocusing capability is now available. our system consists of a separate kinematically mounted table of out own design with a vibration isolation breadboard and positioning systems for sample, microscope and Kirkpatrick-Baez mirrors. The minimum spot size for the current mirrors is approximately 5m×5m. The system has been used for fluorescence mapping and spectroscopy experiments. A new microprobe with x-ray emission spectroscopy capability is being developed.

Bending Magnet Line

Wide Energy Range Monochromator

We currently have an Oxford Si (111) monochromator consisting of a water-cooled first crystal designed by the IIT Center for Synchrotron Radiation Research and Instrumentation (CSRRI) and a 50mm long second crystal which provides an energy range of 4.0keV to 32keV from the fundamental reflection. Both crystals have been chemically polished and have been measured to deliver the theoretical photon flux to the experimental station. The second crystal has Bragg parallel and normal motions and is run at 50% detuning for removal of harmonics. The experimental station is 25m from the source which provides a relatively high photon flux density without the need of focusing optics. The monochromator is exceptionally easy to set through the use of a GUI which allows the user to select an element to be measured.

High Energy Tomography and Photochemistry

The Bending Magnet first optical enclosure contains a 1 m long Pt-coated mirror which can be used to tailor the incident spectrum for photochemistry or photolithography. A three axis (horizontal, vertical, rotational) stage can be used to position the samples for irradiation or for high energy (> 100 keV) tomography.

Detector Systems

The MRCAT sector is currently equipped with 22cm long aluminum spectroscopy ion chambers for use in transmission mode x-ray absorption spectroscopy and 6 smaller Cornell-type ion chambers which may be mounted on the spectroscopy rail for special purposes. Three Lytle-type fluorescence detectors are also available. Data collection is through a standard instrument chain of Keithley electrometers, V-F converters and a 32 channel multichannel scaler. The multichannel scaler permits continuous of the energy and the goniometer detector motors.

The MRCAT instrumentation also includes a single-element YAP scintillation detector and a 19-element solid state detector for dilute XAFS and Fluorescence measurements. At the present time, we are limited to approximately collection times of greater than 6s per data point with the Ge detector. A 4-element Vortex detector is available primarily for use at the Bending Magnet line and additional 4-element Vortex detectors from the APS Detector Pool can be easily integrated into the beamline as needed.

Bent Laue fluorescence analyzers are also available upon request.

Data Acquisition

Data acquisition is handled by the MX system, written by William Lavender. A preliminary manual as well as source code is available at http://mx.iit.edu


Last edited on 16 Dec 2014