ISIS has several access mechanisms by which facility users can apply to make use of neutron and muon beams:
- Direct access: for full proposals, submitted to two deadlines per year and reviewed by Facility Access Panels. Time from proposal to experiment is typically 6-12 months.
- Rapid access: for full proposals, submitted at any time. Reviewed by two FAP members by email. Needs a justification for why the experiment should be run rapidly. Scheduled as soon as feasible.
- Xpress access: for quick measurements, where the user generally doesn't come to the facility.
- Industrial access: either direct, paid-for access or through the Industrial Collaborative R&D scheme.
This document sets our further information ab
What is Xpress Access for?
Xpress access is designed for short measurements which do not warrant a full proposal. Users typically send samples to ISIS and don't themselves come for the measurement. Typical uses of Xpress will include:
- a 1-off crystal structure determination
- an extra data point to finish off a paper
- to test a sample either for its neutron / muon response either prior to proposal submission or at the request of a FAP before allocating full beamtime
- other short, simple tests of experiment feasibility
The Xpress route is not meant as a way to avoid the Direct or Rapid access routes; and should not be used for samples which are, for example, extremely topical, or being studied by other users, or where other considerations mean that peer review should be undertaken before the sample is run. Samples and measurements should also be simple and not need involved safety cases (see below).
How does the Xpress mechanism work?
Users apply for Xpress time through the online proposal system, choosing the Xpress route. Users should always speak with an ISIS instrument scientist before submitting a proposal. Xpress samples require a safety assessment, but this should be uncomplicated by the very nature of Xpress measurements and the samples which are suitable for this route. Xpress proposals are not peer reviewed by FAP members, but are considered from a technical point of view by ISIS staff. Measurements are done either when time happens to be available on an instrument or during instrument days dedicated to Xpress measurements, depending on the instrument.
In principle, all ISIS instruments are available for Xpress measurements (there are a small number of exceptions to this, such as the pressure beamline Pearl, where Xpress measurements are not suitable). More details of Xpress on some instruments are given on the ISIS web pages.
What sort of measurements is Xpress suitable for?
Xpress is designed for short, simple measurements that require very little in the way of set-up, sample handling or safety cases. Listed below are the sorts of experiments which are not suitable for Xpress because they require more complicated preparation work – in such cases, the Direct or Rapid Access routes should be chosen. Experiments and samples not suitable for Xpress:
- Pressure measurements – as these require more complex risk assessments
- Measurements with gas handling or other complex sample environment.
- Samples containing uranium or other radioactive samples requiring handling and storage protocols
- Requirements for prep work beyond filling of sample cans
- Biological samples
- Samples with the following chemical hazards
- Highly toxic materials (these could include heavy metals (Ba, As, Se, Cd), cyanides)
- Pyrophoric materials (these could include alkali metals (Li, Na, K, Ca), fine metal powders, nitrocellulose, metal hydrides)
- Carcinogens (see MSDS)
- Oxidisers (these could include strong acids, chromium oxide)
- Explosives (these could include nitro or azide group containing compounds, peroxides)
Any queries about the suitability of a sample prior to an Xpress run please contact sample safety to discuss it.
Philip King, Marek Jura, James Taylor, January 2018