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Cosmic 100: University of Bristol at Royal Society Summer Science Exhibition

2 July 2012

University of Bristol particle physicists are presenting an interactive display on cosmic rays at the Royal Society Summer Science Exhibition this week.

The exhibit, entitled ‘A one hundred year old cosmic mystery’, explores advances in our knowledge of cosmic rays and particle physics through hands-on activities. The display includes a live link-up to a cosmic ray observatory in Argentina, as well as a spark chamber that can detect cosmic rays hitting the room in which visitors are standing.

Cosmic rays were discovered 100 years ago, but their origin still remains a mystery. In 1912, Nobel Prize Victor Hess made his discovery by taking simple radiation detectors up in a hydrogen balloon and showing that radiation levels increased, rather than decreased, with altitude.

Fellow Nobel Prize winner Cecil F Powell (1903-69), who came to the University of Bristol in 1927 as a Research Assistant in the Physics Laboratory, used cosmic rays to make important discoveries about nuclear particles.

A naturalist at heart, not content with the more abstract quantum theory research being carried out by his peers, Powell became interested in pioneering new methods of directly getting in touch with nature. He used weather balloons to send plates coated in photographic emulsion into the upper atmosphere. By studying the tracks left by cosmic rays in these plates, it was possible to determine what particles had been present. These pioneering studies of cosmic rays led to the discovery of the TT (pi) meson – a combination of an up and down quark.

Powell received the Nobel Prize in Physics in 1950 ‘for his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method’. His discovery is considered by many to be the birth of modern particle physics. He went on to establish an elementary particle physics group at the University of Bristol – one of the first in the country. Today the group plays a key role in many experiments around the world, in particular at the Large Hadron Collider in CERN.

The Royal Society exhibit is a collaboration between the University of Birmingham, School of Physics and Astronomy; Boulby Underground Laboratory; University of Bristol, School of Physics; The Cerenkov Telescope Array; Durham University, Department of Physics; Highgate School , Ilford County High School, Essex; King’s College, London, Department of Physics; University of Leeds, School of Physics and Astronomy; Prior Pursglove College; University of Sheffield, Department of Physics and Astronomy; and Simon Langton Grammar School for Boys, Canterbury.

The Summer Exhibition runs from 3 to 8 July at the Royal Society in London.

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