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Atomic Weapons Establishment at Physics at Work 2018

Atomic Weapons Establishment

What will students see at your exhibit?

Students will have a chance to see the way in which our forensic seismology and structural dynamics teams make use of different wave properties to help underpin our mission of maintaining the UK’s nuclear deterrent. This will mainly be shown through the use of a Rubens tube and a Chladni plate, which will allow the everyday unseen to be seen.

What physics is used?

The exhibit focuses on the physics of waves. Transverse and longitudinal waves are both shown by the Rubens tube. Sound waves from a frequency generator create a moving longitudinal pressure wave. These pressure waves form standing waves at certain resonant frequencies. The gas leaks out of the holes, more so in the ‘nodes’ of the longitudinal standing wave, as these are the compressions so the particles are tightly packed. This causes a higher flame than areas where there are rarefactions, causing the shape of a transverse wave.

The Chladni plate also uses the concept of standing waves, nodes and antinodes. The plate is vibrated at its resonant frequency. Sand bounces away from the areas moving lots – the nodes – and falls into the areas that are not moving - the antinodes. Many patterns can be created, as the plate has many resonant frequencies.

Primarily our presentation will focus on waves, and the phenomena that occur as a result of them. By looking at the behaviour of both transverse and longitudinal waveforms we can show how it is possible to tell the difference between a range of seismological events.

Through our experiments we can expand to demonstrate the way in which basic principles come into play with even the most high-end of systems.

Why is it useful?

Understanding waves within Forensic Seismology is a fundamental requirement to help differentiate earthquakes from nuclear explosions. AWE uses this to provide international collaboration in the upholding and enforcement of the Comprehensive nuclear Test Ban Treaty (CTBT), which was ratified by the UK in 1998.

As our product will potentially be subjected to extreme environments, our Structural Dynamics team provides analysis on how this affects the product and its capability. Understanding waves is a vital element to our understanding in this area as they can cause materials to bend and contort.