Steinberger was born in the city ofBad Kissingen inBavaria,Germany, on May 25, 1921, into aJewish[6] family.[7] The rise ofNazism in Germany, with its openanti-Semitism, prompted his parents, Ludwig Lazarus (acantor and religious teacher) and Berta May Steinberger,[8][9] to send him out of the country.[7]
Steinberger emigrated to theUnited States at the age of 13, making the trans-Atlantic trip with his brother Herbert. Jewish charities in the U.S. arranged for Barnett Farroll to care for him as a foster child. Steinberger attendedNew Trier Township High School, inWinnetka, Illinois.[10] He was reunited with his parents and younger brother in 1938.[8]
Steinberger studied chemical engineering at Armour Institute of Technology (nowIllinois Institute of Technology) but left after his scholarship ended to help supplement his family's income.[7] He obtained a bachelor's degree in chemistry from theUniversity of Chicago, in 1942.[7] Shortly thereafter, he joined theSignal Corps atMIT.[11] With the help of theG.I. Bill, he returned to graduate studies at theUniversity of Chicago in 1946, where he studied underEdward Teller andEnrico Fermi.[7][8] His Ph.D. thesis concerned the energy spectrum of electrons emitted inmuondecay; his results showed that this was a three-body decay, and implied the participation of two neutral particles in the decay (later identified as theelectron () andmuon () neutrinos) rather than one.[12]
After receiving his doctorate, Steinberger attended theInstitute for Advanced Study inPrinceton for a year. In 1949 he published a calculation of the lifetime of the neutralpion,[13] which anticipated the study of anomalies in quantum field theory.[14]
Following Princeton, in 1949, Steinberger went to theRadiation Lab at theUniversity of California at Berkeley, where he performed an experiment which demonstrated the production of neutral pions and their decay to photon pairs. This experiment utilized the 330 MeV synchrotron and the newly invented scintillation counters.[15] Despite this and other achievements, he was asked to leave the Radiation Lab at Berkeley in 1950, due to his refusal to sign the so-called non-Communist Oath.[16][8]
Steinberger accepted a faculty position atColumbia University in 1950. The newly commissionedmeson beam atNevis Labs provided the tool for several important experiments. Measurements of the production cross-section of pions on various nuclear targets showed that the pion has odd parity.[17] A direct measurement of the production of pions on aliquid hydrogen target, then not a common tool, provided the data needed to show that the pion has spin zero. The same target was used to observe the relatively rare decay of neutral pions to a photon, an electron, and apositron. A related experiment measured the mass difference between the charged and neutral pions based on the angular correlation between the neutral pions produced when the negative pion is captured by the proton in the hydrogen nucleus.[18] Other important experiments studied the angular correlation between electron–positron pairs in neutral pion decays, and established the rare decay of a charged pion to an electron and neutrino; the latter required use of a liquid-hydrogenbubble chamber.[19]
During 1954–1955, Steinberger contributed to the development of thebubble chamber with the construction of a 15 cm device for use with theCosmotron atBrookhaven National Laboratory. The experiment used a pion beam to produce pairs ofhadrons withstrange quarks to elucidate the puzzling production and decay properties of these particles.[20] In 1956, he used a 30 cm chamber outfitted with three cameras to discover the neutralSigma hyperon and measure its mass.[21] This observation was important for confirming the existence of the SU(3) flavor symmetry which hypothesizes the existence of the strange quark.[22]
An important characteristic of theweak interaction is its violation ofparity symmetry. This characteristic was established through the measurement of the spins and parities of manyhyperons. Steinberger and his collaborators contributed several such measurements using large (75 cm) liquid-hydrogen bubble chambers and separated hadron beams at Brookhaven.[23] One example is the measurement of the invariant mass distribution of electron–positron pairs produced in the decay ofSigma-zero hyperons toLambda-zero hyperons.[24]
In the 1960s, the emphasis in the study of the weak interaction shifted from strange particles to neutrinos. Leon Lederman, Steinberger andSchwartz built large spark chambers atNevis Labs and exposed them in 1961 to neutrinos produced in association with muons in the decays of charged pions and kaons. They used theAlternating Gradient Synchrotron (AGS) at Brookhaven, and obtained a number of convincing events in which muons were produced, but no electrons.[25] This result, for which they received the Nobel Prize in 1988, proved the existence of a type of neutrino associated with the muon, distinct from the neutrino produced in beta decay.[26]
TheCP violation (charge conjugation andparity) was established in the neutral kaon system in 1964. Steinberger recognized that the phenomenological parameter epsilon (ε) which quantifies the degree of CP violation could be measured in interference phenomena (See CP violation). In collaboration withCarlo Rubbia, he performed an experiment while on sabbatical atCERN during 1965 which demonstrated robustly the expected interference effect, and also measured precisely the difference in mass of the short-lived and long-lived neutral kaon masses.[27][28][independent source needed]
Back in the United States, Steinberger conducted an experiment at Brookhaven to observe CP violation in the semi-leptonic decays of neutral kaons. The charge asymmetry relates directly to the epsilon parameter, which was thereby measured precisely.[29] This experiment also allowed the deduction of the phase of epsilon, and confirmed thatCPT is a good symmetry of nature.[30]
In 1968, Steinberger left Columbia University and accepted a position as a department director atCERN.[31] He constructed an experiment there utilizing multi-wire proportional chambers (MWPC), recently invented byGeorges Charpak.[32] The MWPCs, augmented by micro-electronic amplifiers, allowed much larger samples of events to be recorded. Several results for neutral kaons were obtained and published in the early 1970s, including the observation of the rare decay of the neutral kaon to a muon pair, the time dependence of the asymmetry for semi-leptonic decays, and a more-precise measurement of the neutral kaon mass difference. A new era in experimental technique was opened.[33]
These new techniques proved crucial for the first demonstration of directCP-violation. TheNA31 experiment at CERN was built in the early 1980s using the CERNSPS 400 GeV proton synchrotron. As well as banks of MWPCs and a hadron calorimeter, it featured a liquidargon electromagnetic calorimeter with exceptional spatial and energy resolution. NA31 showed that direct CP violation is real.[34]
He retired from CERN in 1986, and went on to become a professor at theScuola Normale Superiore di Pisa in Italy.[8] He continued his association with the CERN laboratory through his visits into his 90s.[37][7]
Steinberger was awarded theNobel Prize in Physics in 1988, "for the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino".[38] He shared the prize withLeon M. Lederman andMelvin Schwartz; at the time of the research, all three experimenters were atColumbia University.[39]
The experiment used chargedpion beams generated with the Alternating Gradient Synchrotron atBrookhaven National Laboratory. The pions decayed tomuons which were detected in front of a steel wall; theneutrinos were detected in spark chambers installed behind the wall. The coincidence of muons and neutrinos demonstrated that a second kind of neutrino was created in association with muons. Subsequent experiments proved this neutrino to be distinct from the first kind (electron-type). Steinberger, Lederman and Schwartz published their work inPhysical Review Letters in 1962.[25]
Steinberger's first marriage to Joan Beauregard ended in a divorce, after which he married his former student, biologist Cynthia Alff.[42][8] He had four children, two from each of his marriages.[42] His sonNed Steinberger is the founder of theeponymous company for headless guitars and basses, and his daughterJulia Steinberger is an ecological economist at theUniversity of Lausanne.[43] As anatheist and ahumanist, Steinberger was a Humanist Laureate in theInternational Academy of Humanism.[44][45] In his own words, he is noted to have enjoyed tennis, mountaineering and sailing.[8]
In the 1980s Steinberger resumed relations with his native town Bad Kissingen. He often visited Bad Kissingen after that. The school he had attended there was namedJack-Steinberger-Gymnasium in 2001. In 2006 Steinberger was made honorary citizen of Bad Kissingen. "I feel welcome in Bad Kissingen. This is my hometown and I was raised there. I feel as a German again now" he told the Bavarian broadcasting companyBayerischer Rundfunk in 2013.[46]
He died on December 12, 2020, at his home inGeneva. He was aged 99.[16]
^F. Eisler, R. Plano, A. Prodell, N. Samios, M. Schwartz, J. Steinberger, P. Bassi, V. Borelli,G. Puppi, G. Tanaka, P. Woloschek, V. Zoboli, M. Conversi, P. Franzini, I. Mannelli, R. Santangelo, V. Silvestrini, D. A. Glaser, C. Graves, and M. L. PerlDemonstration of Parity Nonconservation in Hyperon Decay.Phys. Rev. 108, 1353 – Published December 1, 1957
^C. Alff-Steinberger; et al. (1963).Siena 1963 Conference Report: 205.{{cite journal}}:Missing or empty|title= (help)
^Istva ́n Hargittai, Magdolna Hargittai (2006).Candid Science VI: More Conversations with Famous Scientists. Imperial College Press. p. 749.ISBN9781860948855.Jack Steinberger: "I'm now a bit anti-Jewish since my last visit to the synagogue, but my atheism does not necessarily reject religion."
