Before your experiment
- Diffraction Cluster (Unlicensed)
Experiment Authorisation Form |
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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. 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. |
Staffing your experiment
You are responsible for running your experiment throughout your time. The facility runs 24 hours a day. 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. It is not reasonable for any individual to be at the beamline for more than 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 our own equipment, gas fittings, lines, and regulators the day before your experiment as this will also minimise setup time. Please note all of our Swagelock fittings and gas lines are in metric sizes and we don't have adapters to imperial fittings. 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, but if you want anything other than these or at non-standard pressures, you should check with the beamline team and be prepared to bring your own regulator. Information on high pressure capillary measurements can be found here.
Vacuum - The beamline has roughing and turbo vacuum pumps. However, we have no way of regulating vacuum so if you require this you will need to provide your own control mechanism.
Additional equipment - e.g. Mass spectrometers, gas manifolds, user supplied experimental setups including cables need to be provided by the users. Cables for electronics in the hutch will need to be a minimum of 5 m so we can feed it through the hutch labyrinth and it can be controlled.
NOTE: All of our Swagelock fittings are in metric sizes. If users have their own setup equipment, they need to bring adapters for their experiment or Swagelock fittings in imperial sizes. We do not have adapters.
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.
Check here to see if your samples need diluting: https://11bm.xray.aps.anl.gov/absorb/absorb.php
Absorption can be reduced by using smaller internal diameter capillaries or diluting with amorphous quartz. Its best to find this out before your beamtime and prepare your samples and have time to purchase the ideal capillaries.
Beamtime start time
Experiments at the Powder Diffraction beamline start (and end) at 8:00 am. The default room temperature capillary setup for the beamline takes ~4 hours plus additional time depending on the sample environment you will use.
Beamline staff will be onsite from 8:00 am at the start of your experiment. Typically beamline staff will do the primary setup of the beamline optics, wavelength calibration and set up sample environment. You should not rely on the beamline staff to set up, mount, modify or control your equipment - you need to be self sufficient at this and plan for this when planning your experiment.
This doesn’t mean you need to be there at 8 am. Your Beamline Scientist will contact you before and discuss what time you should come to the beamline. your Beamline Scientist will be setting up the beamline from 8 am. The early stages of beamline setup do not require the presence of Users. (So you may as well have a lie in!)
Before attending the beamline you must have a valid access card. These are obtained from the User office after you have completed your online training. You MUST NOT enter the main synchrotron building without one.
Energy selection
The Mythen 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 have extensive experience in this and will choose an energy for you depending on the elemental composition of your sample. It may be necessary to change energy to accommodate all samples and this process can take 4 hours and should be factored into your experimental plan. You can check the absorption edges of the elements in your sample using https://physics.nist.gov/PhysRefData/FFast/html/form.html.
