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Particle physics at the Bristol International Balloon Fiesta

19 September 2012

In the summer of 2012 the Centre for Public Engagement was involved with an iconic local festival for the first time – the Bristol International Balloon Fiesta. We joined forces with the School of Physics, the Science and Technology Facilities Council (STFC) and the Institute of Physics to deliver a stand on particle physics with a ballooning twist.

Victor Hess (played by Paolo Baesso) and his apprentice (played by Gabriel Penn) prepare to take flight

Victor Hess (played by Paolo Baesso) and his apprentice (played by Gabriel Penn) prepare to take flight
Image by Beth Cotterell

One hundred years ago particle physicist Victor Hess discovered a form of radiation from outer space known as cosmic rays, sparking a century of particle physics research which has been instrumental in the recent discoveries at the Large Hadron Collider (LHC) in CERN, Switzerland. Hess’s discovery was made by taking an electroscope up to 10,000 ft in a hot air balloon where he noticed that radiation levels increased as he moved away from the Earth, contrary to the accepted hypothesis that the Earth was the source of all radiation. He announced that their origins lay in space – and we now know cosmic rays come from sources such as dying stars and the sun.

Particle physicists from the University manned the exhibition throughout the Fiesta explaining their research and engaging in avid discussion with the public on the elusive Higgs boson.

Rebecca Jones
To celebrate the centenary of his discovery we decided to launch a balloon at the Fiesta up to 10,000 ft, and bring on board a cosmic detector built by local sixth form students to collect live data. Better still we decided to re-enact Hess’s flight in period costume, and record a commemorative video. Our activities were part of the LHC road show tent at the Fiesta run by the STFC. Particle physicists from the University and volunteers from the Institute of Physics manned the exhibition throughout the Fiesta explaining their research and engaging in avid discussion with the public on the elusive Higgs boson. Exhibits included an impressive “HiStrike” machine with a mallet to hit a weight up a cord – signifying the energy of different strength cosmic rays. The exhibition also allowed us to highlight the advances Bristol physicists such as Nobel Prize winner Cecil Powell made to the field since Hess’s discovery.

Visitors enjoying the model of the LHC tunnel

Visitors enjoying the model of the LHC tunnel
Image by Beth Cotterell

For the re-enactment of the flight, we recruited some keen students and physicists to play the role of Hess and his apprentice, with the Drama department providing the authentic costumes. The University Hot Air Balloon Society also kindly agreed to do a tethered launch in the Fiesta arena to allow us to get our shots of the balloons ascent “into space”.

However the main feature was the centenary balloon flight which was scheduled for the morning of Day 2. As this flight would be going way above the usual flight limit of a hot air balloon, to 10,000 ft, we had to get special permission from the Civil Aviation Authority and alert Bristol Airport. We also had two competition prize winners joining us for the flight, one coming from London, and a film crew from Physics World filming the ascent. Due to changing weather conditions, the flight was changed with 3 hours’ notice, allowing just enough time for both prize winners to still make it and causing Physics World to run across Ashton Court in time to get their footage.

For the re-enactment of the flight, we recruited some keen students and physicists to play the role of Hess and his apprentice, with the Drama department providing the authentic costumes.

Rebecca Jones
We took to the skies with the cosmic ray detector in tow, accompanied by three Nuffield Foundation bursary sixth form students who had built the detector as their summer project. Proudly they watched, poised to see their detector collecting the superbly clean data that can be achieved at altitudes of 10,000 ft, only to find out the battery of the detector was dead – having been mistakenly left on all day. “Not to fear – that’s experimental physics for you!” was the comment from one of the physicists, and as a testament to their resilience, their re-charged detector returned the following day for a less glamorous low altitude flight (with on/off switch clearly marked) which proved a great success - gathering real cosmic ray data from the skies!

Rebecca Jones, School of Biochemistry

Please contact The Public Engagement Officer for further information.