News


Half the Alltfedw circuit

Half the Alltfedw circuit

April 2018 - National Resources Wales provide a car park by the Afon Ystwyth near Trawsgoed with two waymarked paths. One of them leads onto Alltfedw, a low ridge to the east of Llanilar and ending fairly abruptly at Trawsgoed. It is mostly covered in forest (Coed Alltfedw). Unfortunately, there had been significant storm damage recently, which hasn't been cleared yet. However, the lower part is accessible with care, while I had to turn round near the summit because the toppled trees were piled up or l... [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


ph375 fg375 ph356 - 3rd-year project

ph375 fg375 ph356 - 3rd-year project

Third-year lab consists of a project for all physics students. This is usually a year-long effort, although joint students do a shorter version in the second semester only. Students generally work in pairs, although finalists are expected to write an individual report at the end.
A wide range of projects is available to choose from on the website, and we are also happy to consider students' own ideas if they fit with the goals of the module. Please speak to potential supervisors!
Each project is structured into a literature review, project planning, experimental and dissemination phase. Projects can be experimental, observational, theoretical or software development.
Dyma fersiwn Cymraeg y ddogfennaeth prosiect BSc hefyd. [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 Maes-llyn layby on the B4343 south of Pontrhydfendigaid
A short lunch-time walk to stretch the legs on a crisp winter day. Totally flat, the walk begins at a layby near Maes-llyn farm on the road from Pontrhydfendigaid to Tregaron, where there is a gate leading onto the former railway trackbed (now cycle path) through the raised bog of Cors Caron. After heading south for a kilometre or so, the continuation of the track is gated off (with the cycle path returning to the road) and the boardwalk circuit branches off to the right and into the bog prope... [more]
Elenydd  4.3km  25m  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]