Advances in instruments and techniques

Advances in ISIS instruments and techiniques over the past year.

Polaris

Polaris will be completely upgraded during the ISIS 2010 long shutdown. When complete, its 38 modules of fibre-coupled scintillation detectors will contain some 400,000 m of fibre optic light guide and will give Polaris a gain of up to a factor of 20 in count rate. Manufacture of the main vacuum tank at Cadinox has been completed, and production of the Debye-Scherrer collimator is currently underway at RAL.

The upgraded Polaris will have a primary flight path of 14 m.

The upgraded Polaris will have a primary flight path of 14 m. Thirty eight detector modules will give a total coverage of ~44% of the maximum possible solid angle.
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Pearl

During the long 2010 ISIS shutdown the high pressure neutron diffraction facility, Pearl, will undergo a major upgrade. The aim is to provide the option of tuning the resolution of the diffraction data while maintaining as large as possible d-spacing range. To this end the full detector compliment is being replaced with a new design of ZnS scintillator detector developed in collaboration with Spain. The secondary flight path is being slightly increased and, combined with the new detectors, this will improve the resolution and the counting stability of the instrument. In addition, a new incident beam collimation system is being installed which will enable neutron flux to be traded for a further increase in resolution. This project is being funded by the Spanish government and being designed and constructed by ISIS in partnership with AVS and Scientifica in Spain.

The Pearl 90° detector in production at Scientifica, Deba, Spain.

Olatz and Natxo Carrera with the Pearl 90° detector in production at Scientifica, Deba, Spain.
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EMU Upgrade

This year has seen a significant upgrade to the EMU muon spectrometer. EMU has been given a new detector array, with three times the number of detector elements providing significant improvements in data rates. It also has enhanced performance for small samples, and is now equipped for dilution refrigerator use. The new instrument has been commissioned and is performing extremely well.

The refurbished EMU instrument

The refurbished EMU instrument provides three times the previous data rate together with other experiment improvements.
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Iris detector upgrade

The detector bank upgrade on the Iris spectrometer was successfully completed in May this year. Following the installation and commissioning of the detector manifold for the pyrolytic graphite bank in March 2008, the upgrade of the detectors for the mica bank is now also finished. Iris is now equipped with state-of-the-art detector electronics and new photomultiplier manifolds with µ-metal shielding to avoid stray field interference from magnet operation on Osiris. We see a much increased detector stability, a strong reduction in stray fields and, in the case of the Mica bank, significant improvements in signal to noise.

Iris results

Iris results from a vanadium calibration standard for the new mica detector bank, showing improved signal-to-noise and resolution.
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First users on HiFi

HiFi is the new ISIS high-field muon spectrometer. The instrument opens up new possibilities for muon studies at ISIS by providing an order of magnitude increase in applied field (up to 5T) compared with existing ISIS muon spectrometers. HiFi took four years to design and build. It is based around a state-of-the-art superconducting split-pair magnet that is cryogen-free and has very high field homogeneity. The instrument is now fully available to the ISIS user programme.

First users on the HiFi muon instrument

First users on the HiFi muon instrument. (left to right) Dr Alan Drew, Dr Laura Nuccio, Leander Schulz, Maureen Willis (Queen Mary University of London) and Dr Iain McKenzie (ISIS) using the instrument to explore spin scattering processes in organic materials relevant to spintronics.
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High fields and low temperatures

The combination of high magnetic field and ultralow temperatures is indispensable for a broad range of neutron scattering experiments. However, problems with the global helium supply have raised significant concerns about the affordability of conventional cryogenic equipment. Oxford Instruments, in collaboration with ISIS, have designed, produced and tested 9T and 14T superconducting magnets which can be combined with a dilution refrigerator producing a base temperature of 60 mK. The systems can be operated continuously with zero helium boil-off. This significantly reduces liquid helium consumption as well as having operational simplicity. The two magnets have been used on Wish and Merlin.

Oleg Kirichek (ISIS) with the new superconducting magnet systems.

Oleg Kirichek (ISIS) with the new superconducting magnet systems.
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Polarised Neutrons

The ISIS polarisation group is on course to deliver polarised neutron capability on both the LET and Wish instruments.  This year saw the construction of the LET polariser and analysis systems, and the LET spin-filter cells, designed to reduce background contamination, are in production. A compact polariser and analyser insert has been constructed for use on Wish. Tests on the Wish beamline showed the device to be working well, with a 3He spin-relaxation time of 82 hours. When the new ISIS 3He optical pumping station is delivered early in 2011, we will be in a position to run wide-angle neutron polarization analysis experiments on both LET and Wish, adding a new dimension to the ISIS instrument suite.

The polarisation analysis insert being lowered into the Wish tank

The polarisation analysis insert being lowered into the Wish sample tank.
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Software

As ISIS instruments become more complex and capable of taking increasingly large data sets in a single run or across multiple runs, so tools for handling data also need to grow accordingly. ISIS has ongoing projects to ensure that software for data reduction and analysis keeps pace with instrument hardware developments.

Mantid is an open-source, multiplatform project for neutron data reduction, analysis and visualisation.  The package supports an increasing number of ISIS instruments, soon to include all Crystallography instruments and progressively the instruments of the Excitations Group. It will eventually be used for all ISIS instruments. ISIS staff are working with developers from Tessella on the project, which now consists of more than 260,000 lines of code. Recently an agreement has been signed with the US Spallation Neutron Source for joint Mantid development – doubling the size of the development team. Mantid supports data reduction for the time-of-flight diffractometer EXED at the Helmholtz Zentrum Berlin, and the Institut Laue Langevin in France is also considering piloting Mantid over the next year.

 

A major sub-project within Mantid is the development of multi-dimensional visualisation software for inelastic and diffraction data. Exploring four dimensional data sets from the Merlin instrument, which can be as large as 100GB, is a challenge, and is one that is set to become greater as instruments such as LET and Wish come online. Capabilities will be built into Mantid to visualise such massive datasets using established open-source libraries that take advantage of multi-core and distributed computing environments. Model fitting of inelastic scattering data will also be integrated into the Mantid framework, allowing users to fit their own models or select from a models library.

Merlin data showing excitations in YBaCo4O7

Merlin data showing excitations in YBaCo4O7. The image shows a 3d plot at fixed energy extracted from the original 4d dataset.
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Biolabs

ISIS houses two biology Laboratories, one in each target station. Both labs provide basic biochemical, biological and biophysical facilities. They are equipped with general lab equipment as well as several more specialised instruments. 

Luke Clifton (ISIS) prepares for studies of bacterial membranes.

Luke Clifton (ISIS) prepares for studies of bacterial membranes on Polref in an ISIS biolab.
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