Obituary Jack Steinberger (1921–2020) Particle physicist who shared Nobel for discovering muon neutrinos. hen particle physicist Jack harnessed a new accelerator at the Brookhaven Steinberger began his career in National Laboratory, New York, and built a 1945, scientists knew about only fast-acting detector that made particle tracks a handful of subatomic particles. visible as trails of sparks. It was on a massive Today, dozens are evident, and scale. A 13.5-metre-thick steel shield, made Wtheir basic building blocks are codified in the from armour plates from scrapped warships, standard model of particle physics. Stein- was used to block all particles except neutri- berger, who has died aged 99, contributed nos, and a 10-tonne spark chamber was con- throughout — from discovering particles to structed to spot the ones produced. grouping them. He shared the Nobel Prize Steinberger moved to Europe in 1968 to in Physics in 1988 (with Melvin Schwartz and CERN, the particle-physics laboratory near Leon Lederman) for a 1962 experiment that Geneva, Switzerland. The multiwire chamber, revealed the existence of two distinct types of which had just been invented there, was able an enigmatic particle: the neutrino. to collect data thousands of times faster than Neutrinos barely interact — they can pass a bubble chamber could. Steinberger used it right through Earth. They have no electric to extend his studies of strange particles. In charge and respond to the ‘weak’ nuclear 1983, he led the design and construction of force, which acts within atomic nuclei and a large experiment called ALEPH to exploit governs radioactivity. They were predicted CERN’s Large Electron–Positron collider. In in the 1930s, to account for the unexplained 1989, ALEPH helped to demonstrate that there energy released alongside electrons in radio- can be no more than three types of neutrino active decay. Steinberger and his colleagues — the electron and the muon neutrinos, and a SOPHIA ELIZABETH BENNETT/CERN SOPHIA ELIZABETH showed that there was more than one type of third associated with the tau particle, another neutrino. They found a second, associated with The desire to exploit new facilities and ‘heavy electron’ discovered in 1975. This neatly the muon — a particle similar to the stable elec- techniques was a hallmark of Steinberger’s completed the story that Steinberger had tron but 200 times heavier and with a shorter research. In 1949, he joined the Radiation begun with his PhD thesis. lifetime. Steinberger also helped to pin down Laboratory at the University of California, Steinberger retired from CERN in 1986, but the properties of quarks, the ultimate constit- Berkeley, where he used an innovative accel- continued to work with ALEPH researchers uents of protons and neutrons. erator to study another cosmic-ray particle, until the mid-1990s. He extended his inter- Born into a Jewish family in Germany, Stein- the pion. He showed the existence of the short- ests to astrophysics and climate change, and berger was evacuated soon after the Nazis came lived electrically neutral pion, the lifetime of in 2015 joined other Nobel prizewinners in to power, arriving in the United States in 1934. which he had earlier calculated theoretically. signing the Mainau Declaration, urging gov- His foster parents in Chicago, Illinois, ensured ernments to limit greenhouse-gas emissions. that he received a high-school education and “After losing one bet with Jack Steinberger was admired for his instinct reunited his family there in 1938. Steinberger and prowess as an experimental physicist, his first studied chemistry at the University of Chi- theorist friends about an intellect as a teacher and supervisor, and for cago. He joined the US Army on his graduation aspect of physics, he paid being a great friend. He was not always right — in 1942, less than a year after the United States up with good wine.” after losing one bet with theorist friends about entered the Second World War. He worked an aspect of physics, he paid up with good wine. with physicists at the Massachusetts Institute He had a deep interest in how nature works, and of Technology in Cambridge on the use of radar But he left for Columbia University in New York enjoyed mountaineering and sailing. to improve the accuracy of aircraft bombing. City in 1950, owing in part to his refusal to sign Uninterested in prizes, he often reiterated After the war, Steinberger returned to an anti-communist oath. There, he exploited his belief that “the pretension that some of us the University of Chicago to pursue physics the newly invented bubble chamber — which are better than others [is not] a good thing”. research. He was supervised by Nobel laureate reveals trails of fast-moving particles in liquid He felt he been dealt lucky cards in his life, and Enrico Fermi, who had demonstrated the first propane or hydrogen — to make discoveries expressed his deep gratitude to the Chicago nuclear chain reaction. Fermi, who had also about the plethora of new particles that were family who gave him opportunities as a child. worked on the theory of the neutrino and being unearthed. These included ‘strange’ In his words: “You have only one life: whatever coined its name, pointed him to a puzzle con- particles, so called because they decay more crops up, crops up.” cerning the decay of the muon, which had been slowly than expected. found in cosmic rays in 1936. The particle broke It was at Columbia that Steinberger and Christine Sutton is a science writer in down into an electron and missing energy. his colleagues conducted their Nobel-prize- Oxfordshire, UK. She is a former researcher in Steinberger attributed the energy to not one winning experiment. Steinberger’s former particle physics and was editor of the CERN but two neutrinos, a hypothesis he confirmed student Schwartz worked out how to make Courier from 2003 to 2015. experimentally in 1948. a beam of high-energy neutrinos. The team e-mail: [email protected] 194 | Nature | Vol 589 | 14 January 2021 ©2021 Spri nger Nature Li mited. All rights reserved. .