ILL Millennium Programme
Diffraction Group
Proposals for a Year 2000-2005 Development Programme
Updated 11 March 2002
In 1999, the ILL Diffraction Group presented five proposals to the ILL Science Council for the years 2000-2005: All five of these proposals have now been approved, after review by the ILL Instrument Committee. The VIVALDI neutron image plate detector has already been commissioned, and the first (detector) stage of the Super-D2B high resolution powder diffractometer will be completed in 2002. The D3 polarized neutron machine has been largely modernized, and work is starting on it’s new cryopad. The dedicated strain scanner has been funded by an EPSRC grant, and a further large grant has been obtained for a related FaME engineering materials lab. Work will start in 2002 on the new large D19 detector, again funded by an EPSRC grant. More recently, new proposals have been presented for DRACULA, a Diffractometer for Rapid ACquisition over Ultra Large Areas, and for CYCLOPS, a CYlindrical Ccd Laue Octagonal Photo Scintillator.
To justify the programme on neutron powder/liquids diffraction (D1A,D1B,D2B,D4,D20), ILL's Science Council requested a review and an assessment of the impact of ILL science. We therefore collected statistics for the different instruments of the number of proposals in the last 2 years, the number of publications in the last 5 years, and the number of citations to all ILL publications.
A lecture on this programme was presented to the October 1999 meeting of the Science Council. (Use the Tab, Enter and Shift keys to move through this lecture, or click on the left-hand title bar after expanding the browser to full screen).
- VIVALDI (Very Intense Vertical Axis Laue Diffractometer or "Thermal LADI") is an ILL/EMBL collaboration for an image-plate diffractometer for small unit cell problems. VIVALDI is like the single crystal machines on pulsed neutron sources, except that the time averaged flux on the sample can be much greater, since a continuous white beam is used. Again it will probably not compete with traditional single crystal diffractometers where the highest precision is needed, but like powder diffraction, VIVALDI will provide rapid surveys with lower precision. Latest News ! The complete instrument was commissioned from SICN Veurey, in consultation with F. Cipriani (EMBL), and commissioned in late 2001.
- A Super-D2B High Resolution Powder Diffractometer. The proposal is to increase both the resolution and the efficiency of D2B by replacing the detector with a bank of 128 commercial high pressure He-3 detectors and collimators, and the monochromator with a vertical and horizontally focusing composite. This will result in an order of magnitude gain in efficiency, a significant gain in resolution, and zero loss of operation of the machine. The ILL Magnetism and Crystallography subcommittees selected this proposal as their first choice, the Powder Review judged it the highest priority, and the Instrument Subcommittee selected it, with D7, as one of their two most highly rated projects (Alpha+). More details were presented in a slide show to the ILL Instrument Committee. Latest News ! The detectors have been purchased with the help of a French ministry grant, allowing the first stage of the project to be completed in 2002.
- A new D3C using a 3He neutron spin filter. The 3He filter technology developed at ILL has now proved itself as a viable alternative to Heusler crystals or polarising mirrors. It will allow the spin polarisation to be independent of the monochromator, allowing the latter to be optimised for maximum intensity and resolution. A spin analysis option can also be added. These improvements, together with the new 10 Tesla cryomagnet, and a dedicated zero-field neutron polarimeter (cryopad) for 3D polarisation analysis, will make D3C a uniquely powerful machine for the investigation of exotic magnetic structures. Latest News ! A start has been made on the new polarimeter, the first stage of the project.
- A CRG for Strain Scanning for Engineering Research. This development, based on a high resolution powder diffractometer like D1A, would provide the world's best reactor based instrument. Such machines are superior when only one or two peaks are needed to map strain, since all of the intensity can be concentrated in a single neutron wavelength. They are also complementary to synchrotron instruments, since very short wavelengths and low angle scattering is not needed, and true through-surface scanning is possible even with heavy metals such as iron. Latest News ! This project will be funded by an EPSRC grant of ~12 MFF over 4 years to a consortium of UK Universities, lead by P. Withers (Manchester).
- A New 2D Microstrip Area Detector for Diffractometer D19. We will replace the present D19 banana detector by an array of eight 2-dimensional microstrip MSDs, with a projected gain in efficiency of x25. D19 will complement cold-LADI, but because the MSD detectors are read in real time, will not integrate background scattering from hydrogen, and will be capable of the higher precision refinements needed to complement X-ray and synchrotron measurements. Further supporting information, including the opinions of eminent biologists and external users has been presented to the ILL instrument committee. Latest News ! EPSRC have provided a large grant for the new D19 detector, to a consortium of UK Universities lead by Professor Judith Howard (Durham).
- DRACULA, a Diffractometer for Rapid ACquisition over Ultra Large Areas. New electronic detectors being developed at ILL will permit much large areas to be covered. DRAC (meaning “DRAGON”, the name of the river used to cool the ILL reactor) will use an ultra-large area detector to collect a 5+ times larger solid angle than now possible with D20. In this it will approach the solid angle of machines like GEM on pulsed sources. The advantage of using a reactor rather than a pulsed source is that the time averaged flux on the sample can be an order of magnitude greater. DRAC will then be the best machine in the world for the study of fast solid state reactions, with cycle times of better than 100 milliseconds. It will compete with GEM-type machines on the new American and Japanese pulsed sources.
- CYCLOPS, a CYlindrical Ccd Laue Octagonal Photo Scintillator. New single crystal diffractometers on spallation sources, with ultra-large area detectors, such as TOPAZ at SNS and SXD-II at ISIS, will allow real-time exploration of reciprocal space and rapid structure refinement. ILL pioneered similar techniques with image plate machines, and retains a potential advantage because of the high flux on the sample from a continuous white neutron source. Yet neutron image plates are not real-time, are only ~20% efficient, and the image decays even as the data is collected. These differences have been made startlingly clear by recent in-situ comparisons of LADI with electronic PSD’s. We propose to build a new machine, the CYlindrical Ccd Laue Octagonal Photo Scintillator, using methods similar to those used for SXD, but with much higher flux. A small prototype machine at ILL, OrientExpress has already proved the principle.
This may seem an ambitious programme, but the CRG strain scanner, D19 and super-D2B will be constructed with external resources, while thermal LADI has been purchased from industry and can be run by University groups as a self-service machine. The D3c 3He project is already well under way with special funding from EPSRC and the CEA, while the super-D2B detector will be finished in 2002 with funding from the French ministry, and hopefully EPSRC.
Return to the ILL Diffraction Group Home Page.