News


Gallops, bales and ducks but no x-rays and no beer - the Ridgeway

Gallops, bales and ducks but no x-rays and no beer - the Ridgeway

July 2016 - Exploring the West Ilsley Downs while waiting for a vacuum problem to be fixed on the beamline at Diamond Light Source. We couldn't have wished for better weather for such a mishap to occur! [more external link]  [other news]

Recent beamtime


SANS experiment on solvent-annealed diblocks on SANS2d

SANS experiment on solvent-annealed diblocks on SANS2d

The original aim of this experiment was to use proton/deuteron contrast to locate remnants of the solvents used in solvent-vapour annealing in our polymer films. As it turns out, the contrast arising from these small amounts of trapped solvent is insufficient to be detected on a sensible time scale. We therefore switched tack somewhat and varied the solvent from more polar (acetone) to non-polar (hexane) and the substrate temperature during annealing from 21C down to 1C. An initial look at the data suggests that they are in line with our findings using GISAXS during the recent commissioning experiment at I22. [more] [beamtimes]

Teaching materials


ph324 ph338 - Condensed Matter Physics

ph324 ph338 - Condensed Matter Physics

This section of the Condensed Matter module covers the different ways of describing the structure of solids: crystal lattices and coordination polyhedra. Diffraction techniques are used to study crystal structures and their imperfections. In the magnetism section, dia-, para- and ferromagnetic states and the transitions between them are compared. Other collective phenomena in solids such as superconductivity and ferroelectricity are also covered. There is also a practical x-ray diffraction workshop included in this module. [more] [teaching]

Research papers


Dynamic strain propagation in nanoparticulate zirconia refractory

Dynamic strain propagation in nanoparticulate zirconia refractory

Residual and intrinsic strains in granular materials have been studied extensively. However, understanding the dynamic strains that cause these resultant residual strains is key to developing better strain-resistant materials. This investigation demonstrates a method for characterizing dynamic strain propagation in granular materials. The specimen is a zirconia based refractory composed of sol-gel-derived zirconia nanoparticles in a potassium silicate glass binder. In situ synchrotron X-ray powder diffraction in flat-plate geometry is used to characterize the sample structure on timescales of the order of 1ms. A 125W CO2 laser is used to strain the sample with a 25ms pulse length. To compensate for the poor flux on this timescale, a pump-probe method is repeated 1000 times and the resulting data are subsequently re-binned to improve statistics. A Gaussian weighting function is also used to introduce better contrast between strained and unstrained frames. TOPAS Academic is used for fitting with a Le Bail model in batch mode. Lattice parameters and sample height are refined during fitting, along with a Lorentzian line width for extracting microstrain broadening. Microstrains, epsilon, in the range of 1.01% < epsilon < 1.46% are reported on a 1ms timescale. [request reprint]  [papers]

Walking in Wales


Low cloud and a little snow on Pumlumon

Low cloud and a little snow on Pumlumon

Pumlumon Fawr from Nant-y-Moch
A surprise sunny cold spell at the weekend between two miserable, murky November weeks gave an opportunity for a quick ascent of Pumlumon Fawr from Nant-y-Moch reservoir. As the camera battery was playing up, I had to resort to using the phone to take pictures - with reasonable results. Starting from the minor road running up the eastern shore of Nant-y-Moch reservoir, I took the hydro track to Llyn Llygad Rheidol, waded through the stream emerging from its overflow and made my way up toward... [more]
Elenydd  10.2km  430m  3.5hrs   [more] [walks]

Other diversions


Centisquare grid for Ordnance Survey maps

Centisquare grid for Ordnance Survey maps

I've written a small web application as an exercise in using the Ordnance Survey's OpenSpace API. It is a rather simple affair that shows a centisquare grid (100m x 100m) on top of a zoomable map to help locating photographs when submitting to Geograph. Of course a much better tool that includes this functionality along with side-by-side maps and satellite imagery is Bill Chadwick's Where's the Path site. It also allows you to draw, import and export tracks and generate track profiles. [more] [other diversions]