Gem Xpress
07 May 2009



Powder diffraction measure-by-courier service using the Gem instrument


Gem Xpress beam time at ISIS is suitable for:

  • new and infrequent users
  • research programmes requiring only limited and/or occasional neutron beam time
  • chemistry programmes operating a tight loop between synthesis and structural characterisation

A total of 1 beam day per cycle on the Gem powder diffractometer will be devoted to this programme.

Samples will only be measured at room temperature and in standard containers.

Please note: if you wish data to be collected from more than one sample you must complete and submit a separate GEM Xpress proposal for each sample.

Standard sample containers

Only sample containers and packaging supplied by ISIS shall be used for sample shipment. The containers shall be sealed appropriately by the user and will not be opened at ISIS.

Containers can be requested from the Xpress online proposal system.

Data output

Fully reduced and corrected high-quality data, ready for Rietveld refinement, will be provided to the user, together with example files and guidelines for refinement. The user is expected to carry out the structural analysis with minimal assistance.

Beamtime limits

Each group applying will be capped at 2 hours per cycle, and will be allocated on a first-come-first-serve basis until the group has reached a total of 10 hours.


If the beam time limits have been attained, or every 12 months in any case, a report shall be submitted to ISIS Facility Access Panel 1 (diffraction) for review, via the User Office, detailing how the beam time has been employed.

FAP1 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.