Polarisation in spin-echo experiments: Multi-point and lock-in measurements

Anton Tamtögl, Benjamin Davey, David J. Ward, Andrew P. Jardine, John Ellis, William Allison

Research output: Contribution to journalArticlepeer-review


Spin-echo instruments are typically used to measure diffusive processes and the dynamics and motion in samples on ps and ns time scales. A key aspect of the spin-echo technique is to determine the polarisation of a particle beam. We present two methods for measuring the spin polarisation in spin-echo experiments. The current method in use is based on taking a number of discrete readings. The implementation of a new method involves continuously rotating the spin and measuring its polarisation after being scattered from the sample. A control system running on a microcontroller is used to perform the spin rotation and to calculate the polarisation of the scattered beam based on a lock-in amplifier. First experimental tests of the method on a helium spin-echo spectrometer show that it is clearly working and that it has advantages over the discrete approach, i.e., it can track changes of the beam properties throughout the experiment. Moreover, we show that real-time numerical simulations can perfectly describe a complex experiment and can be easily used to develop improved experimental methods prior to a first hardware implementation.
Original languageEnglish
Article number023902
JournalReview of Scientific Instruments
Issue number2
Publication statusPublished - 1 Feb 2018


  • Spin echo experiments
  • Atomic and molecular beams
  • Polarisation measurement
  • Diffusion
  • Lock-in amplifier

Fields of Expertise

  • Advanced Materials Science


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