After 35 years of operation, HRPD retains its position as one of the leading high-resolution neutron powder diffraction instruments in the world. However, the scientific scope of modern crystallography and materials science in general has evolved over HRPD's lifetime; furthermore, both hardware and software capabilities have grown. In order to remain at the forefront of neutron scattering science in the coming decades, we plan a complete upgrade of both the instrument and its infrastructure.
This project, dubbed HRPD-X, envisions design of a new non-magnetic sample tank, a new complement of detectors (based on wavelength-shifting fibres), and a new building to house the larger and more capable instrument.
Key Features of the Proposed Upgrade
Substantial increase in the solid-angle coverage of the instrument's detector banks with no loss in resolution for time-focussed data:
x 4.3 in backscattering, relative to the current instrument;
x 2.5 at 90-degrees 2θ;
x 90 in forward scattering.
- Increased coverage at low 2θ will expand the maximum
d-spacing in the longest time-of-flight window from ~ 10 to ~ 45 Å.
- Substantial increase in detector sensitivity from adoption of wavelength-shifting fibres:
Up from ~ 20 % (at λ = 2 Å) with the current scintillator modules to ~ 65 % with wavelength-shifting fibres.
- Substantial reduction in instrumental backgrounds from adoption of a radial collimator.
- Potential improvements in resolution from adoption of additional incident-beam conditioning devices to reduce vertical divergence.
- Ability to carry out experiments in an applied magnetic field by adoption of a non-magnetic sample tank.
Taken together, these enhancements will enable HRPD to extend its world-leading capabilities to include ever small and more complex samples, exhibiting more subtle behaviours and variations in properties, as well as samples contained in more complex environments, including high-pressure devices and magnets.
As a result we expect HRPD-X to remain at the forefront of crystallography based on high-resolution neutron powder diffraction for decades to come.
A short technical paper describing the proposed upgrade was presented at the 2019 ICANS meeting:
Fortes, A. D., & Gibbs, A. S. (2020): HRPD-X; a proposed upgrade to the ISIS High-Resolution Powder Diffractometer. J. Neutron Res., 22, no. 2-3 (2020): 91-98. Proceedings of the 23rd Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-XXIII), Chattanooga, Tennessee, United States, 13-18 Oct 2019. (doi:10.3233/JNR-190130).
Access the free author-accepted manuscript here.