news may 2008

HRPD upgrade with elliptic supermirror guide gives huge boost to instrument performance

(extracted from the call for proposals ISIS from Spring 2008)

A £1.5 million upgrade of the high-resolution powder diffraction instrument at ISIS has been outstandingly successful opening up new areas of science in chemistry, geology and new materials. The HRPD instrument at ISIS is the highest resolution neutron powder diffractometer in the world and is used to study the structure of materials at an atomic scale.

Up to 100 times more neutron intensity is delivered by a new supermirror neutron guide installed over the 100 metres between the neutron source and the instrument. Experiments on the HRPD instrument can now be carried out up to five times quicker, which means experiments that would have taken a few days to complete can now be finished in a few hours. The increased neutron intensity also allows significantly smaller samples to be used. As well as delivering increased flux, the wavelength range of neutrons delivered has also been extended enabling atomic bond lengths in materials to be determined to precisions of around 0.0001 nanometres. This gives immense magnifying power to see atomic displacements in detail that can often be crucial to the physical properties of materials.

Fig. 1: Reflections of the neutron guide installation team from the neutron supermirror.

The neutron guide is a key component of the HRPD instrument enabling neutrons to be transmitted across this long flight path from the ISIS target station to the instrument.

The previous nickel-coated glass guide was over 20 years old and since its design and construction, major developments have been made in “supermirror technology” whereby glass is coated by laying down successive thin layers of nickel and titanium to produce a highly reflective surface for neutrons. The new neutron guide was manufactured and installed by specialist Swiss engineering company SwissNeutronics from Klingnau, Switzerland.

Fig. 2: Enormous neutron intensity gains on the refurbished instrument HRPD will open up new areas of research.

The upgraded instrument will excel in a wide range of applications including crystalline molecular sieves used as catalysts, ion-exchangers and sorbents; environmental science including the control and containment of greenhouse gases; problems in geo-chemistry such as gas and oil recovery and ocean floor stabilisation; and multiferroic materials, where it is possible to finely control the response to electric and magnetic fields.

The project has been delivered ahead of time and on budget and is funded through the Facility Development Project Grant Scheme of the Science and Technology Facilities Research Council.

For further information contact Richard Ibberson (r.m.ibberson(at)rl.ac.uk).

Fig. 3: Data recorded from cerium oxide showing the high-quality information at short d-spacings retaining the intrinsically narrow instrumental peak width.