Quasielastic measurements on direct geometry spectrometers have recently demonstrated the benefits of polarisation analysis to separate the coherent and incoherent scattering that represent the multi-particle and single-particle dynamics from a sample.^1-5 Indirect geometry instruments on pulsed sources offer benefits in terms of cost, sensitivity, resolution and simplicity, but currently no instrument exists with the ability to exploit polarisation analysis.

We are proposing that an updated near-backscattering instrument (SHERPA) with single axis polarisation analysis and similar coverage in Q and ω should be considered as a replacement for IRIS. With progress in neutronic components and the use of a flux and resolution optimised (FARO) design,⁶ initial simulations suggest that SHERPA would achieve an energy resolution of 10-20 μeV and out-perform LET in this configuration by a factor of 130.

We would like to invite the neutron scattering community at this early stage to hear more about this concept and share their expertise to guide the future direction of this project. 

A half-day online workshop was held to discuss the options on the 8th March 2022 and the introductory talks are now available to view. We would appreciate further input and so, if you are interested, please watch the presentations linked below and fill in the questionnaire.

An introduction to the workshop

The SHERPA concept 

Contact: Ian Silverwood​

1. A. Arbe, G. J. Nilsen, J. R. Stewart, F. Alvarez, V. García Sakai and J. Colmenero: Phys. Rev. Res. 2 022015(R) (2020)

2. T. Burankova, R. Hempelmann, A. Wildes and J. P. Embs: J. Phys. Chem. B 118 14452 (2014)

3. T. Burankova, J. F. Mora Cardozo, D. Rauber A. Wildes and J. P. Embs: Sci.Rep. 8 16400 (2018)

4. G. Cassella, J. R. Stewart, G. M. Paternò, V. García-Sakai, M. Devonport, P. J. Galsworthy, R. I. Bewley, D. J. Voneshen, D. Raspino, and G. J. Nilsen: J. Phys. Conf. Ser. 1316 012007 (2019)

5. W. Chen, S. Watson, Y. Qiu, J. A. Rodriguez-Rivera, and A. Faraone: Phys. B: Condens. Matter 564 166 (2019)

6. R. Bewley: Rev. Sci. Instrum. 90 075106 (2019)​