Sophie began by outlining the work she does at Cranfield, although she said this was difficult to define – it involves a lot of different things.  She started as a chemist, later took a Ph.D at Cranfield.  There are no undergraduate students at Cranfield – it starts at Masters level.  She met RAS member Martin Hatton while working at SHARP (on Anglo-Saxon urinary stones), and they did a talk together for RAS in May 2010 on Anglo-Saxons at Sedgeford.  She is now manager of Cranfield’s new laboratory for analysis.  She went on to describe her work with CT (computed tomography) analysis, which besides being used for research, includes quite a bit of commercial work, for example for engineering companies who may want to know the reason behind failures, e.g. of circuit boards: are there voids in the material?

CT scanning is commonplace within the NHS: it is the same technique she is using, using X-rays to digitally reconstruct the volume of an object.  The technique came into use in archaeology later, but is now widely used.  There are more and more requests for scans, and more papers being produced.  This is because the technique is now more accessible, and more affordable, people are more aware of it, and more laboratories are doing this work.  The objects studied have to be held very still, which is difficult when they are fragile.  They have to be propped up in various ways using mounts etc. to be gradually turned through 360 degrees between an X-ray beam and an X-ray detector which produces a digital image, like a dentist who places a piece of film by a tooth, then uses an X-ray machine to produce an image of the tooth on the film.  At each position, a 2D radiograph of the object is taken, giving slices through the object in different planes, and these are added together to produce a 3D image, showing external and internal structure.  A high, 40 micron, resolution can be achieved on small samples. A video can be produced of the rotating object.  So they can look inside an object without having to damage it.

Sophie then went on to give a few case studies involving objects submitted to her laboratory:

The Hanney Brooch – found in Oxfordshire, submitted from Oxfordshire Museum Services and now on public display.  It was quite a rare find, a composite disc brooch, 610-660AD, probably an exotic import.  There are perhaps about 20 in the UK, the majority having been found in Kent; there are others in the Ashmolean Museum.  Sophie showed a video of the brooch turning, its various layers and components revealed.  In the lab they looked at the composition of various components in the brooch, such as garnets.  Under the frontal metal disc is a layer of paste containing calcium carbonate, then more metal underneath that.  One thing the scan revealed was an unsuspected void inside a raised feature on the front of the brooch; they will look at other brooches to compare this structure.

Cremation Urn – from the Birdoswald Roman cemetery, submitted by English Heritage. The urn had been excavated down to the material contained inside.  This+ossibly contained pieces of chainmail, plus some larger objects.  Were these part of the same material, or wrapped in it?  The CT scan cannot say what the material is but can give its density, and can show slices through the objects in the urn, in different planes.

Skull – from a churchyard excavation.  One of the skeletons found was very interesting, possibly a female, approximately 40+ years old, perhaps post-medieval.  There were three noticeable holes in the skull with well-defined edges – they had not healed.  The skeleton’s pelvis was also riddled with holes.  Had the holes been caused by the burial environment, or had the person had cancer of the marrow?  It was thought that this was very likely a case of multiple myeloma.  The request for the CT scan was to find out if there were any other, invisible, holes or lesions within the bone, and indeed more holes were found entirely contained within the bone.

Yvonne Masson