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XRF_beamline.md 6.54 KiB

X-Ray Fluorescence beamline (XRF)

Ref: Milan Prica, Roberto Borghes, Valentina Chenda (SPE)

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.

There is extensive user documentation on the Elettra website written by the beamline scientist, Ilaria Carlomagno.
https://www.elettra.eu/lightsources/elettra/elettra-beamlines/microfluorescence/useful-procedures.html

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 iaea-server.elettra.trieste.it:20000

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. <-- Issue fixed in 2022.

Control system machines

Beamline controls and EXAFS experiments run on Elettra hardware and software.

  • xrf-control-01.blcs.elettra.trieste.it: Dismissed in 2023.

  • xrf-control-01.blcs.elettra.trieste.it: Virtual machine that hosts the Tango database (port 20000) and all the Tango devices (except the IAEA ones, see below). Ubuntu 18.04 and Tango-9.3.4. Login with VUO account as on the new installations.

  • iaea-server.elettra.eu: 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

Both xrf-desktop-01 and xrf-desktop-02 have been reinstalled in 2023 with the Ubuntu 18.04 LTS and Tango-9.3.4. Python3 versions of all important packages are available (PyTango, hdf, numpy...) Login with VUO credentials.

  • xrf-desktop-01.blcs.elettra.trieste.it: Main workstation for controlling the beamline and the EXAFS experiments. Logbook typically runs on this host.

  • xrf-desktop-02.blcs.elettra.trieste.it: Backup workstation with the same setup as the main workstation but with a much smaller screen.

Both machines have VNC access used extensively by the beamline scientists.

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 runs either from its Taurus GUI or from a command line tool that uses python properties files for its configuration. The acquisition is performed by the DonkiOrchestra. Over the years additional scans have been added and are occasionlly used like XRR, XSW. For detailed information see: https://www.elettra.eu/lightsources/elettra/elettra-beamlines/microfluorescence/how-to-run-exafs-xrr-and-xsw-scans.html

High level CLI

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.)