Category: AQA Unit 1 Particles/ Quantum/ Elec

Physicist’s atom struggles revealed

Physicist’s atom struggles revealed

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New Scientist: Drone-wrecking laser gun to sail on US warship

New Scientist: Drone-wrecking laser gun to sail on US warship.

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Donald Glaser obituary

Donald Glaser Obituary

Scientist who won the Nobel prize for physics in 1960 for the invention of the bubble chamber…..

Donald Glaser, who has died aged 86, won the Nobel prize for physics in 1960 for his invention of the bubble chamber, which made the world of subatomic particles visible and led to many further discoveries. In the 1950s and 60s, before the advent of modern electronics, which dominate high-energy physics today, Glaser’s bubble chamber was one of the most powerful tools for revealing the ephemeral existence of a plethora of subatomic particles. The discovery of hordes of novel particles, whose behaviours showed them to be cousins of the more familiar proton, neutron or pion, revealed that these families are made of more fundamental constituents – the quarks. The quark model has become a foundation of the current “standard model” of the fundamental particles and forces.

Glaser was a 25-year-old faculty member at the University of Michigan when he conceived of the bubble chamber. A homely example of the effect that Glaser developed is that of opening a bottle of beer. Releasing the bottle’s cap causes a sudden drop in pressure, whereby bubbles start to rise through the liquid. Glaser’s idea was to keep a liquid at high pressure, near to its boiling point. In such circumstances, a gentle drop in pressure will cause the liquid to start boiling, an effect well known to mountaineers who, at altitude, can brew a cup of tea at lower temperatures than at sea level.

However, if the pressure drop is sudden, the liquid remains liquid even though it is above its boiling point. This “superheated liquid” is unstable and can be maintained only if left undisturbed.

Glaser’s genius was to realise that if electrically charged particles shoot through a superheated liquid, a trail of bubbles forms as they ionise atoms along their paths. Initially too small to see, they rise up, growing to be large enough to be photographed. The process is very delicate; wait too long and the whole liquid will boil, so Glaser’s idea was to release the pressure and then restore it quickly. Particles entering the liquid during the critical moments of lowered pressure could be photographed.

Initially he made a minute demonstration device, a small glass phial containing a mere 3cl of diethyl ether. This delicate apparatus was able to show the trails left when cosmic rays or particles emitted by a radioactive source passed through.

His idea was, at first, regarded with less than enthusiasm. The US Atomic Energy Commission, and the National Science Foundation, both refused financial support, regarding his scheme as too speculative. His first paper on the subject was apparently rejected because it used the word “bubblet”, which was not in the dictionary. When he asked to speak about his invention at a meeting of the American Physical Society in Washington in April 1953, he received similar lack of enthusiasm, but then had a slice of good fortune.

The organisers had assigned Glaser a slot at the end of the meeting’s final day – a Saturday – when many participants would already have left. On the first day, however, his luck turned by a chance meeting over lunch with Luis Alvarez, a leading nuclear physicist from Berkeley.

Alvarez asked Glaser if he was speaking at the meeting and Glaser said that his 10-minute talk was the final slot when many would have gone home. Alvarez admitted that he too would be unable to be present, and asked Glaser what he was going to report on. Alvarez was immediately impressed, realised that here was a breakthrough, and arranged for a colleague to hear the talk.

In 1959, Glaser moved to Berkeley and the bubble chamber became a practical device in high energy particle physics. It was here that Alvarez’s team developed large versions of Glaser’s device, eventually 2m long, filled with liquid hydrogen, constructed of metal and with glass windows, through which trails of subatomic particles could be photographed. The iconic images adorned the walls of physicists’ offices during the latter half of the 20th century, and the discoveries of particles using this device led Alvarez himself to a Nobel prize.

Glaser was born in Cleveland, Ohio, the son of William, a businessman, and his wife Lena. He received his early education in the public schools of Cleveland Heights, Ohio, and took his BSc in physics and mathematics at the Case Institute of Technology in 1946. After completing his PhD at the California Institute of Technology in 1949, he joined the faculty at Michigan.

After winning the Nobel prize, Glaser shifted his interests to molecular biology, and into applying biotechnology to medicine and agriculture. He also revealed the true version of a popular misconception about his discovery. An oft-told story is that Glaser had his inspiration for the bubble chamber when watching the bubbles rise in a beer glass at the student union. The reality was subtly different. Having made the discovery, and become famous, he would be asked over drinks by colleagues, as if puzzled, what was so profound in such a trivial phenomenon?

He is survived by his second wife, Lynn, whom he married in 1975; and a son, William, and daughter, Louise, from his first marriage, which ended in divorce.

• Donald Arthur Glaser, physicist, born 21 September 1926; died 28 February 2013

• This article was amended on 11 March 2013. The original gave the date of Glaser’s second marriage as 1960. Amendments have also been made to a section on the development of the bubble chamber at Berkeley.

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Dark matter as elusive as ever – despite space station results | Stuart Clark

Dark matter as elusive as ever – despite space station results | Stuart Clark

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LHC to enter ‘new realm of physics’

LHC to enter ‘new realm of physics’

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Synchrotron yields ‘safer’ vaccine

Synchrotron yields ‘safer’ vaccine

Producing vaccines against viral threats is a potentially hazardous business and that’s why manufacturers have to operate strict controls to ensure that no pathogens escape.

British scientists have developed a new method to create an entirely synthetic vaccine which doesn’t rely on using live infectious virus, meaning it is much safer.

What’s more the prototype vaccine they have created, for the animal disease foot-and-mouth, has been engineered to make it more stable.

That means it can be kept out of the fridge for many hours before returning to the cold chain – overcoming one of the major hurdles in administering vaccines in the developing world.

The research, published in the journal PLOS pathogens, was a collaboration between scientists at Oxford and Reading Universities, the Pirbright Institute, and the UK’s national synchrotron facility, the Diamond Light Source near Oxford.

Diamond is a particle accelerator which sends electrons round a giant magnetic ring at near light speeds.

The electrons emit energy in the form of intense X-rays which are channelled along “beamlines” – into laboratories where they are used to analyse structures in extraordinary detail.


Synchrotrons have been used before to analyse viruses at the atomic level, but the technology has advanced considerably to enable scientists to create a stable synthetic vaccine.

“What we have achieved here is close to the holy grail of foot-and-mouth vaccines.

Unlike traditional vaccines, there is no chance that the empty shell vaccine could revert to an infectious form,” said Dave Stuart, Life Sciences Director at Diamond, and MRC Professor of Structural Biology at the University of Oxford.

“This work will have a broad and enduring impact on vaccine development, and the technology should be transferable to other viruses from the same family, such as poliovirus and hand-foot-and-mouth disease, a human virus which is currently endemic in South-East Asia.”

These human disease threats, like foot-and-mouth, are all picornaviruses.

Viruses are inherently unstable and fragile, but picornaviruses can be studied using X-ray crystallography.

Diamond Light Source The Crystal Lab uses robots

This enables the protein shell of the virus to be analysed at the atomic level – something a billion times smaller than a pinhead.

As with any vaccine, the aim is to prompt the immune system to recognise this outer shell and destroy the pathogen before it has time to lock onto cells and infect them with its genetic material.

In this research the scientists created a synthetic viral shell, but lacking its pathogenic RNA interior – the genetic material the virus uses to replicate itself.

Crucially they were able to reinforce the structure of the viral shell to make it stronger, to improve the stability of the vaccine.

Pre-clinical trials have shown it to be stable at temperatures up to 56C for at least two hours. Foot-and-mouth is endemic in central Africa, parts of the Middle East and Asia, so this would be a significant improvement over existing vaccines.

With current foot-and-mouth vaccines it is difficult to distinguish between immunised livestock and those which have been infected.

That proved to be a major hurdle in controlling the foot-and-mouth outbreak in the UK in 2001 because it would have prevented the export of livestock.

But the synthetic vaccine should allow scientists to show the absence of infection in vaccinated animals.

“The foot-and-mouth-disease virus epidemic in the UK in 2001 was disastrous and cost the economy billions of pounds in control measures and compensation,” explained Dr Bryan Charleston, Head of Livestock Viral Diseases Programme at the Pirbright Institute.

“This important work has been a direct result of the additional funding that was provided as a result of the 2001 outbreak to research this highly contagious disease.”

The potential hazards of working with viruses was underlined in 2007 when the Pirbright laboratory site was identified as the source of a leak which led to an outbreak of foot-and-mouth disease.

Polio, another picornavirus, which exclusively affects humans, has been eliminated from nearly every country in the world, although it stubbornly persists in Nigeria, Pakistan and Afghanistan.

The need for secure vaccine production will become even more vital should polio be wiped out.

“Current polio vaccines, which use live virus for their production, pose a potential threat to the long-term success of eradication if they were to re-establish themselves in the population.

“Non-infectious vaccines would clearly provide a safeguard against this risk”, said Dr Andrew Macadam, a virologist specialising in polio at the National Institute for Biological Standards and Control in Hertfordshire.

“This technology has great potential in terms of cost and biosafety.

“Any design strategy that minimises the chances of accidental virus release would not only make the world a safer place but would lower the bio-containment barriers to production allowing vaccines to be made more cheaply all over the world.”

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Planck telescope maps light of the big bang scattered across the universe

Planck telescope maps light of the big bang scattered across the universe

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LHC wraps up antimatter ‘flip’ story

LHC wraps up antimatter ‘flip’ story

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