The ORNL neutron diamond anvil cell program commenced at the SNS’s High Pressure Diffractometer, SNAP, where still the majority of experiments with this type of cell are conducted. A comprehensive development program on diamond cells with single-crystal diamonds is in progress and the latest development has now achieved over 100 GPa at room temperature: B. Haberl et al. Sci. Rep. 13, 4741 (2023).

Combination with low temperatures down to 7-10 K limits the pressure to 20-40 GPa. See here for capabilities on the beamline.

ORNL also supports a DAC gas loader that is most typically used for loading of Ar as pressure-transmitting medium into SNAP DACs. Please contact the beamline team for further details, capabilities and constraints.

In addition to these single-crystal anvil DACs specific to the SNAP High-Pressure Diffractometer, the use of large culet anvils for spectroscopy and single-crystal samples has been explored. The most common cell resulting from these efforts uses polycrystalline Versimax® anvils and is capable of pressures up to a maximum of 10 GPa. This cell has been trialed for spectroscopy and has been used across various single-crystal diffractometers at SNS and HFIR. See here for more details: Haberl et al. HPR 37, 495 (2017) and Haberl et al. RSI 89, 092902 (2018).

For experiments on SNAP, please directly contact the SNAP Beamline Team. For experiments on DEMAND, please directly contact Yan Wu. For further possible experiments, future opportunities and general enquiries, please contact Jamie Molaison.

Neutron diamond anvil cells

*NOTE: Development is in progress to couple these DACs with ultra-low temperatures below 1.4 K.

**NOTE: Development on the use single-crystal samples with single-crystal anvil DAC is in progress.

***NOTE: Maximum possible pressure varies depending on compressibility of sample, pressure medium, exact loading and details of a given experiment. The provided values are to simply provide a benchmark.

Policy for the provision of neutron diamond anvil cells:

• The need of a DAC has to be explicitly requested in the beamtime proposal, otherwise the provision of a DAC cannot be guaranteed.
• Users must contact the instrument team as soon as possible (minimum 8 weeks) prior to the beamtime to discuss details of the experiment.
• Users should arrive well in advance for the experiment (typically 2-3 days) and always a full day before beamtime starts.  
• Standard ORNL DACs  are provided. 
• One DAC will be provided per beamtime visit. Its use is solely for the completion of the proposed experiment. Provided that adequate resources and components are available, a second DAC might be available, contingent upon instrument staff approval.
• Samples need to be available at least a week prior to the beamtime to allow for the preparation of the DAC as soon as resources are available.
• In special cases, samples may be requested at the beginning of the cycle for feasibility assessment. Beamtime scheduling may be contingent on those results.
• A successful loading is not guaranteed, especially on the first attempt. 
  - Unsuccessful preparations may lead to cancellation of the beamtime, and the user should resubmit the (modified) proposal.
  - Alternatively, the beamtime can go ahead if there is an approved alternate sample added to the proposal.
• Various pressure-transmitting media are available; gas loading has to be requested preferably in the beamtime proposal. It should always be discussed in advance. 
• Staff members that make significant contributions for the preparation of the cell and sample loading should be co-authors of any publication resulting from the experiment.
• Any decision regarding any issue that affects the safety of the equipment ultimately lies with the instrument staff.
• The equipment has to be operated under the health and safety rules provided and the advice of the instrument staff must be followed.