16 Oct 2008



Merlin is a high count rate, medium energy resolution, direct geometry chopper spectrometer.


Merlin has been in user operation since 2008. It was designed to be a high intensity, medium energy resolution spectrometer that would complement the high-resolution MAPS spectrometer, and replace the HET spectrometer. Merlin’s design exploited recent advances in technology with a supermirror guide to enhance flux, as well as 3 m long position-sensitive detectors in a vacuum, making it idea for the study of single crystals. The detector bank covers a massive π steradians of solid angle with an angular range from –45o to +135o in the horizontal plane, and ±30o in the vertical plane. This allows large swathes of Q,ω space to be accessed in a single run. Since 2014, Merlin has been running in event mode, and by using the new Gd chopper combined with a disk chopper, it is able to run in repetition-rate multiplication (RRM) mode, allowing users to simultaneously measure with several incident energies.


Recent proposal rounds have seen significant number of beamtime proposals rejected by the panel for similar reasons. The Excitations group and Facility Access Panel wish to help users to submit good proposals so would point out the following reoccurring issues of missing information in proposals that is detrimental to their scores, together with straightforward remedies:

  • Lack of evidence that a large single crystals exists or that a sufficient number of co-aligned crystals can be aligned for the experiment. This can be resolved by including a picture (with scale bars)
  • Lack or unclear presentation of relevant structural and physical property characterisation of the materials to be studied. This can be resolved by presenting diffraction and physical properties characterisation of your samples in the proposal.
  • Lack of details regarding what will be measured during the experiment which makes it challenging or in some cases impossible for the viability and merit of the proposal to be assessed during review. This can be resolved by proposers contacting ISIS staff prior to proposal submission.

Contact information for Merlin instrument

Location and contact information for the Merlin beamline

​​​01235 778397