PACE - Proper Analysis of Coherent Excitations
21 May 2021







Wha​t is PACE?

PACE will be a software application that enables a step change in the rapidity and quality of analysis of neutron experiments on the ISIS spectrometers in the Excitations Group 

The goal is to provide an integrated visualisation, simulation and fitting environment on massively parallel and distributed computing, and which interfaces to third party modelling codes. It will:

  • Allow realistic simulations to be performed before and during the beam time to make the most effective use of neutron beam.
  • Enable quantitative analysis of t​he full set of data collected during the experiment, with proper account of instrument resolution.
  • Lower the barrier for users to analyse their data, so increasing the number of publications and reducing the time between experiment and publication.

The Data Analysis bottleneck

The latest spectrometers at ISIS – LET, MAPS and MERLIN – create four dimensional maps of the scattering intensity S(Q,w)  as a function of momentum, Q, and frequency, w, at the rate of 1 – 2 TB per day.

The technical bottlenecks to data analysis include:

  • Most functions of Horace, the current 'gold standard' application for visualisation and analysis of such data, are not parallelised and cannot operate on the latest data volumes.
  • Computer codes that quantitatively model the data are not implemented for high performance computing (HPC), or their output is not integrated into the analysis framework.
  • Proper account of resolution – whether for powder or single crystal data – is mostly not performed, as current codes are not parallelised and require HPC to be feasible.

Goals of PACE

PACE will build on the capabilities of the current Horace software for single crystal data analysis, and include and extend the features of powder analysis familiar to users of Mslice in Mantid or the earlier Matlab version.​

Its key features will be as follow


  • S(Q,w)  model evaluation.​
  • To work in parallel across multiple computers (i.e. distributed computing) on IDAaaS (ISIS data analysis as a service), but also run on standalone workstations and laptops.​​
  • Available for both Matlab and Python user environments.
  • Creation of, and integration with, the application Euphonic to compute scattering from phonons for single crystals and powders from many third party codes e.g. CASTEP, VASP, ABINIT, Quantum ESPRESSO, WIEN2k, CRYSTAL).
  • Interface to SpinW for the calculation of scattering from spin waves.
  • A well-defined interface to other third party models code for S(Q,w) and S(|Q|,w​), or user-written models written in Python or Matlab, so that these models can be straightforwardly used with the rest of the PACE functionality.
  • Proper account of instrument resolution function – for both single crystal and powder data – as a matter of routine.​
  • Fitting of parameters in modelling codes, with resolution function convolution.
  • Command line operation from Matlab or Python by default.​
  • If project resources permit: the construction of a GUI 'workbench' for managing the analysis of data with refinement of parameters in resolution broadened models for scattering​.

More information

A presentation that gives a more detailed overview of PACE and its current status is available here:

PACE is being developed by a small team of software engineers, with a Project Scientist ( and Technical Lead (, and an advisory board made from STFC and external staff that advises on the direction of the project, goals and scope. Useful project documentation is as follows:

Project Brief - background and summary of project goals
Project Management Plan - breakdown of the project plan into deliverables, with ​Gantt chart
Gantt Chart - more easily readable version of the Gantt chart in the project management plan
Board Presentation - Most recent presentation to the Project Advisory Board (December 2020)
Board minutes - Minutes of the most recent Project Advisory Board (December 2020)

To return to Excitations software pag​e, click here.

Contact: Perring, Toby (STFC,RAL,ISIS)