Evolution of existing instruments and design and construction of new ones provide fresh opportunities for materials investigations. Developments over the past year include both first and second target stations.
Good progress has been made on the project to build a new high-field muon spectrometer. Hifi – which will allow applied fields of up to 5T – is now into its construction phase. The experimental area has been prepared and surveyed; the large magnet support structure has been assembled; all of the detectors have been delivered; and a variety of other services are being installed. The magnet is in construction by Cryogenic Ltd and due for delivery in January. We hope that the instrument will be ready for commissioning experiments by the end of the year.
Merlin is a new high flux chopper instrument that was built to replace the HET spectrometer. It is now operational and performing as predicted. The incident flux is nearly 20 times that of HET at 10meV and with position sensitive detectors we have 70,000 pixels covering a solid angle some 8 times larger than HET. Experiments that would take a day on HET now typically take less than an hour. In its first month of operation Merlin has seen huge competition for time and is already producing high-profile papers.
Significant progress has been made with design work for the major upgrade to the Polaris diffractometer. This project, funded from the STFC Facilities Development scheme with contributions to the design work from Spain, will provide large count rate increases coupled with significant improvements to the instrumental resolution at backscattering angles. The major components of the new instrument (vacuum tank, detectors, incident beam collimation, radial collimator) have been designed and the overall layout approved. Installation of the new instrument is scheduled for early 2010.
A related programme, with funding form the Swedish research council, Vetenskapsrådet, is developing a suite of new sample environment equipment to exploit the enhanced capabilities of the new instrument.
Installation of a high-reflectivity supermirror guide on Hrpd is now complete. Supermirror technology, allied to a unique geometric design of the 100m long guide, has enabled flux grains (of up to a factor of 100) that have revolutionised instrument performance. Furthermore, experiments on small samples and in cases where sample volume is limited due to sample environment equipment for compounds where high resolution is specifically required will become tractable for the first time.
Iris has undergone an extensive detector upgrade including new photomultiplier-tube manifolds for the graphite and mica analyser banks; addition of µ-metal shielding to avoid stray-field interference from cryomagnet operation on neighbouring instruments; and improved stability by use of GEM-type detector electronics. The new graphite detector bank has been operational since March 2008, leading to a much-improved detector stability and a 50-fold suppression of stray-field effects, as well as a doubling of detected flux. Installation of the mica detector assembly is scheduled for the end of the year.
The Surf upgrade programme has continued with installation and commissioning of new hardware and software, including a new detector linear encoder, a new transverse goniometer at the sample position and revised computer controls for motion. New sample environment controls for the water bath and Langmuir film balance (Nima trough) has enabled much more satisfactory operation. A Matlab-based package for simultaneous fitting of non-polarised data at multiple contrasts is nearing completion. Its main advantages are a simple windows-based interface and the ability to directly load ISIS raw data.
Vesuvio has just had a major instrument upgrade. As a result of collaboration between ISIS, Milan University and Rome University under the EC funded e.VERDI project, a completely new method of detecting eV neutrons has been developed and has been installed at forward scattering angles. There are a number of advantages of the new technique, including significantly better energy resolution, reduced detector saturation and improved stability – so that Vesuvio measurements are greatly improved.