Donald Glaser obituary

Publié le par The Guardian - Frank Close

The Guardianpublished 05/03/2013 at 16:00 GMT by Frank Close

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

Donald Glaser

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, af 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. From this, Alvarez developed Glaser's basic idea, turning it into the practical device for revealing the trails of subatomic particles, and creating iconic images, which adorned the walls of physicists' offices during the latter half of the 20th century, and which 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.

In 1959, Glaser moved to Berkeley and worked closely with Alvarez and bubble chambers. 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, over drinks colleagues would ask him, as if puzzled, what was so profound in such a trivial phenomenon?

He is survived by his wife, Lynn, whom he married in 1960, and a son and daughter from his first marriage, which ended in divorce.

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

Publié dans Avis de décès

Pour être informé des derniers articles, inscrivez vous :
Commenter cet article