Three Axis instrument for Low Energy Spectrometry

ThALES - Three Axis Low Energy Spectrometer

The ThALES project is a collaboration between ILL and Charles University, Prague.

Its construction was funded by the Czech Ministry of Science and Education.


ThALES is optimized for the measurement of excitations in single crystals in the range of about 0.2 to 10 meV. With its high neutron flux, which is worldwide leading, and its very low background, it can be used to measure particularly weak signals. It allows for extreme sample environment (low temperature, high magnetic fields and pressure) and can be used with neutron polarization analysis.
Its main applications include magnetic excitations in unconventional superconductors, low-dimensional and frustrated magnets and various quantum phenomena, magneto-elastic or multiferroic materials, and heavy-fermion systems, among others. It can also be used for high-precision diffraction studies.

Discover some examples.

Strengths of ThALES

The accessible momentum (Q) and energy (ħω) transfer range fits with the needed dynamical range for measuring excitations in many magnetic systems

  • Typical cold TAS energy resolution from 0.05 to 0.4 meV, depending on the incoming neutron energy
  • Unrivalled cold neutron flux at the sample position (2.5·108 n/cm2/s for incident energies around 10 meV) due to direct view on the high-flux horizontal cold neutron source (HCS) of the ILL and optimized neutron optics
  • Clean beam (velocity selector etc) and very low background
  • Flexible choice of beam conditions (different monochromators, analyzers, guides)
  • Routine operation of complex sample environment
  • Polarization Analysis
  • Easy interchange between single analyser-detector mode (for high-flux studies in restricted regions Q and ω), and the Flatcone multiplexed analyser-detector mode