Commit 479168aa authored by Milan Prica's avatar Milan Prica
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Beamline description - first draft

# X-Ray Fluorescence beamline (XRF)
Ref: Milan Prica, Roberto Borghes, Valentina Chenda
Last updated: Feb. 5, 2021
## Experimental Activities
XRF beamline is developed by Elettra Sincrotrone Trieste and operated in partnership
with the International Atomic Energy Agency (IAEA).
X-Ray Fluorescence is a versatile technique which can investigate solids, liquids,
artworks, air particulates, inks, etc… It provides information on the elemental
composition of a sample.
At the XRF beamline, experiments can be carried out under ambient conditions or in
the ultrahigh vacuum (UHV) endstation, where the pressures can be lowered down to 10-9mbar.
The UHV endstation is equipped with a 7-axes manipulator to adjust the
sample orientation with respect to the X-ray beam and/or the detectors.
Available techniques
- 2D XRF and XANES: quantitative chemical analysis over different areas of the sample;
- Grazing Incidence XRF and XANES: ideal for nano-layered structures or shallow dopants
in semiconductors with nm depth resolution.
- Total Reflection XRF and XANES: for ultra-trace elemental/chemical characterization of
liquid samples residues and micro/nanoparticles on smooth surfaces;
- X-Ray Reflectivity (XRR): for structural analysis of thin films and multi-layers.
## Troubleshooting
Fluorescence experiments are controlled by IAEA software running on their Windows machines.
We can reach IAEA tango database from our network and vice-versa.
IAEA Tango database is
XRF Monochromator is prone to malfunctions due to a very complex design. It includes
a collimator and a refocusing mirror in the same chamber with the monochromator.
The monochromator has 5 channels: Si, InSb, HE, ME and LE. For the first two, the crystal
separations may be regulated. Motor controllers include Galil, SmarAct, PI and Newfocus.
On the xrf-desktop-01 workstation the network speed has changed a few times from gigabit
to the slowest setting, 10Kb/s. The cause is yet unknown.
## **Control system machines**
Beamline controls and EXAFS experiments run on Elettra hardware and software.
- ****: Virtual machine that hosts the Tango database
(port 20000) and all the Tango devices (except the IAEA ones, see below). OS: Ubuntu 16.04.
Development/admin user is controls.
- ****: is the old Windows PC located in the corner of the XRF control
room. Remote access is only possible with TightVNC. Beamline staff has the login credentials.
Tango devices (all C++) for IAEA detectors and 7-axes manipulator run on the host.
An Astor-simulating application that starts and stops tango devices is running on the host.
Regular Astor cannot be used due to the starter issues but Jive is available.
## **Beamline workstations**
- ****: Main workstation for controlling the
beamline and the EXAFS experiments. OS: Ubuntu 16.04. Development/admin user is controls,
while the beamline user is xrf. DonkiLog, DonkiLauncher, Taurus 4.6 panels and command-line
experiment control scripts run on it. Scripts are located in /home/xrf/Documents/scripts/.
- ****: Backup workstation with the same
setup as the main workstation but with a small screen.
## **High level TANGO devices**
- **xrf/monochromator/energy**: Tango device for the monochromator used to set the energy.
The energy value is calculated from angle of incidence with the inversefunc method from the
pynverse library as the position to energy formula based on the monochromator kinematics is not
invertible otherwise. The monochromator device controls channel selection, angle of incidence
and crystal separation values, while the pitch and roll motors of each crystal are excluded
in the current implementation. An Executer script, xrf/monochromator/set_energy, is used to
avoid backlash when changing energy to a lower value by setting an even lower value first.
All the scans are performed by moving from lower to higher energies.
- **xrf/acquisition/exafs_scan**: An Executer script that controls the EXAFS scans.
It is highly configurable and it may be run either from its Taurus GUI or from a command line
tool that uses python properties files for configuration. The acquisition is performed
by the **DonkiOrchestra**.
## **High level CLI**
- ****: A command line tool found on the two workstations that configures
and runs any number of EXAFS scans. Also controls the HOS and 7-axes manipulator.
It is entirely configurable with python's property files.
## **Instrumentation TANGO devices**
The following Tango devices run on the IAEA server and are controlled/acquired by both
IAEA and Elettra software:
- BrukerSpectometer : Bruker detector
- KeithleyPicoAmmeter : Photo-diode
- ElettraPicoAmmeter : BMS
- SevenAxesManipulator : controls the movements of 7 axes of the chamber manipulator.
Used only from IAEA GUI:
- AmptecSpettrometer : XRR (X-Ray Reflectivity) scans of theta/2theta.
- XiaXmapSpectrometer : not in use.
## **Motion control Tango devices**
- AxisG2: it is the new Galil C++ Tango device from A. Abrami.
All instances are configured so that the AxisInit command does the initialization.
- PiezoPiE871: a modified C++ Tango device from DESY for the two PI positioners
that move pitch and roll of the first (Si111) crystal. Positioners are encoderless
and the initialization is perfomed by a DefinePosition(Value).
- NewFocusPicoAxis: A C++ Tango device for pitch and roll motors of all crystals
except the Silicon. They are automatically initialized.
- SmaractMCS: A Python Tango device for MCS1 SmarAct positioner that moves the
InSb crystal separation. It must be initialized with FindReferenceMark command.
(If the motor cables were removed, a Calibrate command is necessary first.)
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