18 Jan 2011



Spin-echo small-angle scattering measure-by-courier service using the Offspec instrument


SESANS Xpress Access at ISIS is suitable for:

  • new and infrequent users who want to test the feasibility of a potential SESANS experiment prior to submitting a full proposal
  • existing users that need to probe their results or systems further because they are not yet sufficiently well-understood, or well-developed, to warrant a proposal in their own right
  • existing users that have a ‘desperate need’ to make a small number of additional measurements on samples related to their recent beam time proposals (eg, to complete a parametric data set, or ‘round-off’ a PhD thesis) 
  • the facilitation of ‘blue sky’ and/or ‘in-house’ research
  • Commercial Users only requiring small durations of beam time and who are willing to accept ISIS involvement in the running of their samples – billing for this service is on a per hour basis.

Experimental criteria

1 day per cycle on the OffSpec instrument will be devoted to Xpress Access.

The standard Xpress Access beamtime allocation per sample will be 30 minutes with an additional 30 minutes for each additional “P0” empty beam measurement required for normalisation.

Measurements will normally be performed at 25°C (298 K). However, users may propose other measurement temperatures in the range 5-95°C (ie, those possible with a standard ethylene-glycol water bath). Temperature variation work will only be performed after all ambient temperature measurements are completed (to remove the possibility of thermally-induced damage to other samples) and the time to change temperature and reach temperature equilibrium will be “charged” to a users Xpress Access beam time allocation. The exchange rate for this will be 2 minutes per °C temperature change.

No guarantee is given that measurements will take place on any particular day, even if advertised, and normal peer reviewed experiments will take priority. When Xpress Access samples cannot be run they will be held over – subject to their useful lifetime – until a new measurement session can be scheduled, or will be returned to the user if so requested.

Users must provide a suitable estimate of the size regime within which they anticipate the samples will exhibit structure in order that the appropriate spin-echo length regime may be chosen. Measurements requiring more than one spin-echo range will be treated as separate samples and incur a loss of data collection time because of the time taken to retune the echo system.

Users must provide details of the sample thickness that should be measured if using standard Quartz cuvettes.

Standard sample containers

Where ISIS supplies packaging it must be used for sample shipment.

Samples in aluminium foil ‘packets’ may be sent by whatever route is appropriate to the hazard that they present, but it is the responsibility of the sender to ensure that they comply with all necessary packaging and transport regulations.

Data output

New and commercial users will be provided with fully reduced and corrected data. More experienced users will simply be provided with details of the relevant files and expected to perform their own data reduction.

At this time, no analysis or interpretation of the data will be provided for any users except where this is part of a separate collaboration.

Data will become public access after three years, or on publication if sooner.

Beam time limits

Xpress Access will be capped at 3 hours of beam time per cycle per group. Beam time will be allocated on a first-come first-served basis.


If the beamtime limits have been attained, or every 12 months in any case, a report shall be submitted to ISIS Facility Access Panel 3 for review, via the User Office, detailing how the beam time has been employed.

FAP3 may recommend continuation of the Xpress Access mode or may require a Direct Access or Programme Access proposal before further beam time is allocated.

Data policy

Data collected using Xpress are subject to the normal ISIS policy regarding publication of scientific results, and bibliometric criteria, among others, will be used to assess the productivity of the scheme.