George Pickett, scientist who worked at record temperatures

With more than a dozen aluminium beer barrels stacked in racks against the wall and a complicated arrangement of pipes and valves, George Pickett’s laboratory at Lancaster University looked like a typical student union bar. In fact, it was just a couple of steps away from the coldest known spot in the universe and the barrels contained helium gas, a fluid even more precious than student beer.
Pickett was by any literal measure the coolest scientist in the country. In 1993 he used nuclear refrigeration techniques to chill a small piece of copper to a record low of seven-millionths of a degree above absolute zero (-273.15C), below which temperatures can drop no further.
The purpose of Pickett’s work was to observe how materials lose their usual characteristics at unusually low temperatures and his “cryostat” device used several different methods for cooling. “It’s like a series of Chinese boxes. The further in you go, the colder it gets,” he told The Observer. The cryostat is first bathed in liquid helium, which is kept at four degrees above absolute zero; the helium is then cooled further using a “dilution refrigerator”; finally, an enveloping magnetic field is switched off, kicking temperatures down a final few millionths of a degree.
In the laboratory Pickett was acutely aware that every external source of energy threatened to produce a pulse of heat that might raise the temperature. As a result, his refrigerator sat inside a vacuum flask, known as a Dewar (after Sir James Dewar, the Scottish scientist and pioneer of low-temperature studies), to insulate the material from everything around it. Meanwhile, the room’s tin-plated walls acted as a “Faraday cage” to exclude any stray electric fields and radio waves that might unwittingly increase the temperature.
In addition, visitors were warned not even to nudge the two pillars supporting the beam from which the Dewar hung. Those pillars sat on air springs, taken from tanker lorries, to dampen any vibrations that might be translated into heat. Although it was impossible to isolate the apparatus completely, Pickett reckoned that he got the rate at which heat is absorbed down to a millionth of a millionth of a watt.
While other researchers were accelerating particles close to the speed of light and smashing them together to try recreating conditions close to the Big Bang, Pickett and his team were heading in the opposite direction. “Stephen Hawking and his like are historians of the universe. What we are doing has never happened before,” he told The Independent. Indeed, one of his experiments was described as “the Big Bang in a drop of helium” and resulted in an article in the journal Nature, one of many published papers.
When David Lee, an American academic, shared the Nobel prize in physics in 1996 for his work on superfluidity in the isotope helium-3, the citation gave credit to Pickett and his research group.
George Richard Pickett was born in Bedford in 1939, the son of George Pickett and his wife Sarah (née Okell). He was educated at Bedford Modern School and Magdalen College, Oxford, before taking his DPhil at the Clarendon Laboratory. Rumours, never substantiated, suggest that he never graduated from Oxford because of an unpaid library fine that he stubbornly refused to settle. His early heat-capacity measurements at Oxford were followed by investigations at Helsinki University of Technology in Finland, where he worked with Olli Lounasmaa, one of the founders of European low-temperature physics.
In 1965 he married Deborah Fonge. She died in 2000. He is survived by their daughters, Elizabeth and Catherine. His subsequent partner, Cora Martin, a former administrator in the physics department with whom he hosted many legendary parties, died in 2022.
Pickett joined Lancaster University as a senior visiting fellow in 1970 and remained there for more than half a century. In the early days much of his equipment and the low-temperature environment he created had a Heath Robinson feel, with holes cut in the roof and pits dug by hand. In fact, he was developing a new type of nuclear demagnetisation refrigerator designed for cooling superfluid helium-3 at ultra-low temperatures. He first broke the record for a low temperature in 1984, reaching 12 millionths of a degree above absolute zero. A German group claimed also to have reached this figure, spurring him on to break it again in 1993, though lower temperatures have since been achieved elsewhere.
In 1988 he was awarded a personal chair in low-temperature physics. Yet even when promoted to professor he eschewed a grand office, preferring instead a cubby-hole under the departmental stairs where he could personally solder the wires on his cryostat. Not that such humility prevented him from grandly sweeping through corridors on urgent departmental business. He continued working in the Lancaster ultra-low temperature laboratory until his last days, continually seeking the lowest temperatures and making pioneering contributions to the understanding of quantum fluids.
Former students recalled a man of huge knowledge, immense charm and great wit who was known for addressing students of many nationalities in their own languages. Others described his withering stare and innate scepticism of anything and everything. One recalled being probed for his understanding of an issue, adding: “When I ventured a response to one of his questions, his response was ‘Like **** it is’, before going on to deconstruct and then reconstruct my understanding.”
Pickett had a gift for explaining physics, sometimes on the back of a napkin in the Sultan of Lancaster Indian restaurant. He also imparted the well-known academic wisdom that there are only two types of people in this world, “big shits and little shits”. He regarded himself as one of the former.
George Pickett, professor of low-temperature physics, was born on April 10, 1939. He died on July 21, 2024, aged 85