A cloud chamber and the birth of helium atoms.

The tracks here show the natural radiation in the atmosphere around us. Thicker tracks are big heavy alpha particles, whispy ones are beta particles, but they all work in the same way.

The atmosphere in the chamber contains a lot of alcohol vapour. When charged particles fire through the atmosphere they cause little droplets to form, and these are the clouds you can see.

This is similar to how a track forms behind an aeroplane, where the exhaust can help the droplets of moisture form together into a cloud.

When you then add an Americium pole into the chamber, the alpha particles emitted (with their two protons and two neutrons) grab electrons and form Helium atoms. 

Watch the full video with Dr Peter Wothers on YouTube.

Medical radiation may be reduced to one-sixth with new mathematical discovery

One of this century’s most significant mathematical discoveries may reduce the number of measuring points to one-sixth of the present level. This means reduced exposure to radiation and faster medical imaging diagnostics.

Eight years ago Australian-born mathematician Terence Taolaunched a completely new and highly sophisticated mathematical theory which may be set to bring about enormous savings in the health sector as well as in the oil industry. The theory is called compressed sensing, and enables compressive sampling without having to look at the raw data first. Physicists at the University of Oslo, Norway refer to the method as one of this century’s most significant mathematical discoveries.

“The idea is to solve a task by involving as few measurements as possible. Whenever data capture is expensive, investment in this new mathematical approach may soon prove cost effective,” says Professor Anders Malthe-Sørenssen at the University of Oslo’s Department of Physics to the research magazine Apollon. He was completely bowled over by the theory when he happened to attend a talk given by Tao a few years back. Today, Tao is considered one of the world’s most eminent mathematicians. He was only 24 when he, as the youngest person in history, was made Professor of Mathematics at the University of California fifteen years ago. His theory is now generating interest among mathematicians all over the world.

SIX TIMES FASTER: The new mathematical method will make it possible to perform an MR examination six times faster than today. This means that hospitals will be able to perform far more examinations without having to buy any more MR scanners. Credit: Illustration: Knut Løvås

Brown bears return to Chernobyl after a century away

Scientists have captured what is believed to be the first photographic evidence of brown bears within the Chernobyl Exclusion Zone (CEZ).

Camera traps, used by a project assessing radioactive exposure impacts on wildlife, recorded the images.

Brown bears had not been seen in the area for more than a century, although there had been signs of their presence.

The exclusion zone was set up after an explosion at the Chernobyl nuclear power plant in Ukraine in April 1986.

“Our Ukrainian colleague, Sergey Gashchak, had several of his camera traps running in one of our central areas over the past few months in order to start to get a feel for what (wildlife) was there,” explained project leader Mike Wood from the University of Salford.

He told BBC News that data retrieved from one of the cameras in October contained images of a brown bear.

“There have been suggestions that they have existed there previously but, as far as we know, no-one has got photographic evidence of one being present on the Ukrainian side of the exclusion zone,” Dr Wood said.

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The UN International Year of Light and Light-based Technologies officially begins today with the opening ceremony in Paris, France. This international event is part of a collaborative effort between UNESCO and other scientific bodies wishing to promote the study of light science as a potential solution to the current global challenges in energy, education, agriculture and health. Oxford Medicine Online has celebrated this momentous event by exploring some of the innovative ways light is already being harnessed to solve medical challenges in this infographic. You can also view the infographic as a PDF to learn more about the medical applications of light.

To discover thought provoking content about radiation from Oxford Journals, explore the Journal of Radiation Research, Radiation Protection Dosimetry, and the Journal of the ICRU today.


Pierre Curie was born on this day in 1859.

Pierre Curie was a French physicist famous for his research in crystallography and magnetism. Together with his wife Marie, they isolated radium and polonium in 1898 and later discovered the properties of radium and its transformation products. Together they were awarded half of the Nobel Prize for Physics in 1903 for their work on the spontaneous radiation discovered by Becquerel, who was awarded the other half of the Prize.

On the 19 June 1903 Pierre, accompanied by his Marie, lectured at the Royal Institution during a Friday Evening Discourse on Radium. These photos show the copper alloy pot and box which held an early sample of radium that he demonstrated - still radioactive to this day.