News


A small circuit into Cwm Rheidol from Pontarfynach/Devil's Bridge

A small circuit into Cwm Rheidol from Pontarfynach/Devil's Bridge

August 2018 - A quick evening wander into the Rheidol gorge, starting from the centre of Pontarfynach/Devil's Bridge, where there is usually ample parking space by the side of the main road. After following the road in the direction of Aberystwyth up to the edge of the village, we took a gate to follow the path over grassland to the edge of the gorge, just above the Vale of Rheidol trackbed. The path then follows along the edge of the wooded slope and alternates between grassland and broadleaf forest. ... [more] [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


A small circuit into Cwm Rheidol from Pontarfynach/Devil's Bridge

A small circuit into Cwm Rheidol from Pontarfynach/Devil's Bridge

Cwm Rheidol from Pontarfynach/Devil's Bridge
A quick evening wander into the Rheidol gorge, starting from the centre of Pontarfynach/Devil's Bridge, where there is usually ample parking space by the side of the main road. After following the road in the direction of Aberystwyth up to the edge of the village, we took a gate to follow the path over grassland to the edge of the gorge, just above the Vale of Rheidol trackbed. The path then follows along the edge of the wooded slope and alternates between grassland and broadleaf forest. ... [more]
Elenydd  5.4km  230m  2hrs   [more] [walks]

Other diversions


Swapping images with JavaScript

Swapping images with JavaScript

This is a JavaScript function to swap one image for another when the viewer clicks the picture. Repeated clicks toggle between the two images. [more] [other diversions]