Before your experiment
Below is a checklist of what needs to be done before coming onsite. More detailed information about these including access cards, guesthouse and travel funding can be found below and on the user office webpage.
Things to do
Plan beamtime - equipment to bring onsite, staffing, setup changes, chemistry laboratory induction, experimental considerations.
Complete online inductions.
Complete experiment authorisation. The EA form must be completed 5 days before your experiment, and will be reviewed by the user office, safety and the beamline teams. The earlier you get this process started the better. See a list of things to include in the EA on the Safety page.
Ship samples/gases if needed.
Samples can also be shipped to the AS. However, your EA must be approved before shipping otherwise they will not be accepted at our stores. See this document for details of how to correctly ship samples to and from the synchrotron.
Plan Beamtime
Staffing your experiment
You are responsible for running your experiment throughout your time. The facility runs 24 hours a day so experiments should be adequately staffed. It is recommended that at least two people be present at or near the beamline during experiments at all times and it is not reasonable for anyone to be at the beamline for >12 hours at a time.
What to bring to your beamtime
Ensure you bring all required equipment onsite as the beamline has limited resources. Consider bringing your own equipment, gas fittings, lines, and regulators the day before your experiment as this will also minimise setup time. The beamline cannot supply ferrules or capillaries.
Gases - The beamline has a limited range of regulators for common gases including N2, Ar, O2, CO2, H2. Check with the beamline team if the regulator required is available and be prepared to bring your own regulator. Information on high-pressure capillary measurements can be found here.
Vacuum - We cannot regulate vacuum so if you require this you will need to provide your own control mechanism.
Additional equipment - e.g. User-supplied experimental setups including cables need to be provided by the users.
NOTE: All of our Swagelok fittings are in metric sizes. If users have their own setup equipment, they need to bring adapters for their experiment or Swagelok fittings in imperial sizes. We do not have adapters.
Setup & sample environment changes
If your beamtime is only one day, no setup changes are allowed after the initial setup at the start of your beamtime.
Setup changes not considered:
Changing between capillary and linear/XY stages. Eg: hot air blower and batteries.
Changing from transmission to reflection geometry. Eg: capillaries and furnace.
These will not be considered
Setup changes will only be considered if your allocated beamtime is:
More than one day, and
It is in the proposal
There is minimal downtime such as changing from hot air blower to cryostream.
Setup changes include changing X-ray energy.
However, allowing changes will be determined on a case-by-case basis and up to the discretion of the beamline team.
If your beamtime spans multiple days and you would like to change the setup:
Simple setup changes must begin no later than 2:00 PM.
Complex setup changes must begin before 10:00 AM.
This ensures enough time for:
Disassembling the existing setup
Installing and aligning the new setup
Conducting beamline alignment
Providing user training on the new configuration
Contact staff to determine the appropriate time to start the setup change.
Best Practice: Setup changes can take considerable time and reduce overall data collection. To maximize the experimental efficiency, the users are advised to minimise the number of setup changes during the allocated beamtime.
Sample absorption
Data quality is lower for highly absorbing samples in Debye-Scherrer geometry as the Bragg intensity is dependent on the diffraction angle and scattering may not be from the entire sample volume. Absorption impacts low angle peaks more due to the longer X-ray path length, can cause lower intensity, peak shifting and peak splitting in the worst case. Absorption can be reduced by using smaller internal diameter capillaries, diluting with amorphous quartz or using higher energy X-rays.
The absorption can be calculated using this absorption calculator. Assume a packing fraction of 0.5. Ideally, the absorption coefficient muR, should be < 1.
Energy selection
The Mythen-II detector is very sensitive to fluorescence, and the contribution of a fluorescence background to the measured data is minimised if the energy selected is below the absorption edge or greater than 6 keV above an absorption edge. This can make energy selection challenging, however the beamline team will choose an energy depending on the sample elemental composition. You can check the absorption edges of the elements in your sample using the NIST scattering tables.