CLRC News
CLRC News
The Rutherford Appleton Laboratory's Open Days ran from 26 June - 2 July,
and attracted an estimated 4,700 members of the public, school children,
academics, people from industry and other invited guests. ISIS opened its
doors to display its science and instrumentation, with demonstrations giving
an introduction to the facility, and exhibits in the ISIS experimental hall
providing insights into crystallography, muons, large scale structures,
excitations and computing. Highlights of the ISIS displays included an
extended visit by Professor Chadwick, (played by Chris Frost), who explained
to impressed audiences how he discovered the neutron, and a working set of
manipulators, used for remote handling of the ISIS neutron target, skilful
use of which enabled visitors to pick up and recover sweets. A new ISIS
video explaining the work of the facility could be viewed in a small cinema
area; interactive exhibits included demonstrations of synchrotron magnet
operation, neutron reflectometry, atomic vibrations and detector encoding.
In addition to the main display areas, school parties were invited to
undertake extended projects lasting about an hour on subjects such as
diffraction and superconductivity; a comment from one young visitor: 'I
really enjoyed looking round ISIS and being able to use all the machines on
the tour. I found ISIS really amazing, the way the machine works is
absolutely staggering'.
Philip King
More information can be found on the Internet at
http://www.isis.rl.ac.uk/Crystallography/
The crystallographic exhibits were admired by visitors of all ages.
School children enjoyed colouring in the pages of 'Jewels' designed by
Kevin Knight,
click here to see the page of jewels
Bill David made some polyhedral cut out models which proved very popular and
were much in demand. (some made up ones are shown on table before the
children )
Older visitors were more interested in the display of crystals, the models
of crystal structure and the '3D' glasses and software which showed rotating
molecules of paracetamol and C60.
An animated slide display gave a general introduction to the study of crystals;
we are hoping it can be reformatted for the WWW as a more permanent record of
Open Days 98.
The Computing Division at RAL was demonstrating uses of the Internet showing visitors how to search for interesting topics, they helpfully found several references to crystal growing for me, sites with many pictures of crystals, and a site with an explanation of the inner workings of a quartz watch. I have links to these sites into an 'Introductory' page on the BCA web site to try to attract children to crystallography. 'Introduction' is accurate but dull, one member suggested I call it 'Crystal Wonderland'. Take a look and let me have your comments and more links to add.
RAL staff have been helping local schools to get started on using the Internet.
They provided a list of useful links including the schools online
pages at:
http://sol.ultralab.anglia.ac.uk/pages/schools_online/
and BBC's Tomorrow's World at
http://www.bbc.co.uk/tw/
It was said that nobody would travel to Daresbury for a meeting on World Cup Final weekend. But how wrong they were! The X-rays in Magnetism workshop attracted over 50 delegates, eager to talk about work carried out at many of the major Synchrotron laboratories world-wide, including the APS (Argonne, USA), ESRF (Greoble, France), LURE (Orsay, France) and, of course, the SRS at Daresbury. Opening the meeting, Bob Cernik invited participants to enjoy the facilities at Daresbury, especially the 'touchy-feely' exhibits in the newly-opened Science Centre where coffee and poster sessions were held. Indeed, throughout the meeting, a number of eminent Professors were spotted eagerly taking Bob up on his offer!
The serious business was started by Gerrit van der Laan, and we had to put on our thinking-caps to learn about the famous sum-rules in X-ray dichroism - plus some new ones - and how they can be derived using very attractive diagrammatic techniques. The next two talks described some interesting X-ray diffraction results from very different systems. John Hill outlined the mystery of PrBa2Cu3O6.9 - the '123' superconductor that isn't, and discussed how the discovery of a long-period static magnetic modulation in both Pr and Cu might shed light on this anomaly. X-ray diffraction was also used to confirm unambiguously the presence of orbital ordering in another transition metal oxide, LaMnO3, by the purely resonant nature of the scattering and its unique polarization-dependence. Moving away from 3d metals, Sean Langridge described diffraction studies of uranium compounds, where very strong resonance enhancements are observed, and measurements on the antiferromagnet DyF4Al8. The latter was shown to exhibit large variations in the L2,3 branching ratio with temperature, which was attributed to subtle changes in the magnetic ground-state. Continuing with the crystal diffraction theme, Ted Forgan focused on magnetic structure studies of Nd, and outlined the Herculean task of refining a vast number of X-ray diffraction peaks to shed light on the complex array of structures exhibited by this metal.
Theoretical developments were very much in evidence throughout the workshop. Atomic calculations of Stephen Lovesey, describing electric dipole and quadrupole transitions in NiO, were presented and compared with the predictions of dichroic sum-rules. A rather different approach - relativistic multiple-scattering theory - was championed by Paul Strange. For those of us left wanting more after an elegant overview, there is Paul's new book from Cambridge University Press! Ceri Jenkins described how self-consistent linear-muffin-tin-orbital calculations on Gd/Mo multilayers were able to correlate the induced Mo moment with a volume-expansion in the spacer-layer.
One of the dominant topics of the workshop - diffraction from magnetic multilayer structures - was addressed though numerous studies with both soft and hard X-ray diffraction techniques. Denis Raoux demonstrated how the wavelength and energy of soft X-ray beams were ideally suited to exploit the strong magnetic resonances in 3d metal multilayer structures, providing a highly-sensitive, element-specific probe of magnetic ordering. This theme was continued by Tom Hase, who reported measurements of magnetic coupling (both bi-linear and bi-quadratic) in Cu/Co GMR multilayers, performed recently at the SRS on a prototype soft X-ray diffractometer. But hard X-ray studies were not be left out, and particularly pretty examples were described by Denis Roaux and John Goff, who presented measurements of the magnetic profiles of induced moments in Ce and Pr layers, respectively. George Srajer outlined X-ray diffraction studies confirming the transition from aligned to twisted coupling in Fe/Gd multilayers.
Bulk dichroism measurements were discussed by Steve Collins, in the form of X-ray Faraday Rotation, and Pedro Montano, who showed some fascinating, and quite unexpected, results from Gd metal. The sensitivity of circular dichroism was evident from Derek Eastham's talk on cobalt clusters.
Magnetic inelastic scattering, in the form of Compton scattering, provides a complementary approach to studying ferromagnetic materials, probing spin-densities in momentum-space. John Duffy described the current state-of-play, giving examples of 4f and 3d magnetism, and showing how magnetic Compton profiles provide an extremely sensitive test-bed for band-structure models.
Summing-up, Malcolm Cooper reflected on a highly successful workshop, and closed the meeting in time for British delegates to get home for the third-place playoff, and the French to celebrate their team's victory in the Final the following day.
Steve Collins
Daresbury Laboratory
see URL http://wserv1.dl.ac.uk/SRS/VUV-IR/
The 1st Vacuum Ultra Violet Circular Dichroism (VUVCD) meeting was held in the Synchrotron Radiation Department at Daresbury Laboratory. VUVCD is a technique which is used by many biologists to provide important quantitative information on the proportions of alpha helix, beta sheet and random content of their systems. It is also used by many protein crystallographers as an ancillary structural tool.The use of the SRS for CD, rather than commercial off-line systems, has significant benefits for this community.
About 50 delegates from UK academia and industry attended this first meeting to review the work of the current UK national facilities at King's College, London, Stirling University and the SRS and to highlight the potential for a proposed new beamline at the SRS to provide an extreme flux SRCD facility. SRCD, ( Synchrotron radiation circular dichroism ). offers a larger wavelength range than conventional systems and hence a more accurate determination of protein secondary structure. More importantly, the high intensity of the SRS means that very fast dynamic experiments can be carried out (approx 1 ms) and projects such as protein folding are currently benefiting from the facility. A stopped-flow device has been developed at DL which is currently fastest in the world and available for measurements of this type.
Some research using CD facilities at the SRS would test current theories on the mis-folding of the prion protein which has resulted in the BSE epidemic. Other speakers had similar projects . Delegates agreed that a National Structural Biology Centre would be a world leading facility and provide a mechanism for co-ordinating CD within the UK. An application has been made to the BBSRC for funds to construct this facility.The new beamline would also transfer to DIAMOND, the new machine. For further details contact:
Dr Elizabeth Towns-Andrews
tel: (01925) 603357 email; [email protected]
Click here to return to BCA homepage