News


A sightseeing walk in Paisley on a dreich January morning

A sightseeing walk in Paisley on a dreich January morning

January 2017 - While in Paisley for work, I had a quick walk around the town centre before heading back down the M8. The light wasn't great on this grey January day but it was dry and I managed to get some shots of the University, Town Hall, Paisley Abbey and the Coats Observatory. I'll be back in the summer! [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


Quantum Physics

Quantum Physics

I no longer teach this module but have decided to leave the notes online for general reference. These pages give an overview of simple quantum systems which can be solved analytically, increasing in complexity up to the hydrogen-like atom, while delivering the necessary mathematics in examples. The concept of approximating solutions to the Schrödinger equation by linear combination is introduced and applied to atoms more complex than hydrogen and to molecules and solids made up of many atoms. The quantum-mechanical property of spin is discussed in terms of its implications for experimental physics. [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


Boardwalk circuit in Cors Caron

Boardwalk circuit in Cors Caron

Cors Caron from Lay-by below Allt Ddu
Just a short walk to stretch the legs on a Saturday afternoon. Starting from the old reserve car park, effectively a lay-by on the B4343, we followed the alignment of the abandoned Aberystwyth-Caerfyrddin/Carmarthen railway, which now serves as a long-distance cycle path. After passing the new-ish visitor centre, a small boardwalk circuit leads into the bog and past some ponds, remnants from the times when peat was dug here. A short branch leads to the massive glass-fronted bird hide, althoug... [more]
Elenydd  4.4km  20m  1hrs   [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]