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


GISAXS of selective solvent annealed PS-PMMA films

GISAXS of selective solvent annealed PS-PMMA films

Following our in-situ GISAXS experiment at DESY to study the morphological changes to diblock films during selective solvent vapour annealing (SVA), we really needed a few more data points to fill in the parameter space of polymer weight ratios and solvent polarity, at least with ex-situ data of the end product of the SVA process. When Paul Staniec at I22 was looking for a few ex-situ samples to commission his new GISAXS sample environment and beamstop assembly, we had an opportunity to get some of these additional samples measured. [more] [beamtimes]

Teaching materials


ph327 - Atomic Physics

ph327 - Atomic Physics

In this lecture, we're looking at the internal structure of the electron cloud of an atom, investigate how we can interact with it by triggering transitions between the different electronic states using spectroscopic methods, and derive the shape of the periodic table from the states available in atoms of the different chemical elements. Interactions between electronic states and forces internal and external to the atom are also considered, and mathematical methods which enable us to predict transitions and explain spectra. [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


Basic MySQL syntax

Basic MySQL syntax

I keep forgetting the arcane syntax of MySQL queries, so I've put a cribsheet of the most common commands together. [more] [other diversions]