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.
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