Jack Steinberger

Infobox Scientist
name = Jack Steinberger
box_width =


imagesize =150px
caption = Jack Steinberger
birth_date = May 25, 1921 (age 87)
birth_place = Bad Kissingen
nationality = Germany-United States
ethnicity =
field = Physics
known_for = Discovery of the Muon neutrino
prizes = Nobel Prize in Physics in 1988 Jack Steinberger (born May 25, 1921) is a German-American physicist currently residing near Geneva, Switzerland. He co-discovered the muon neutrino, for which he was given the Nobel Prize in Physics in 1988.

Childhood and Emigration to the United States

Steinberger was born in the city of Bad Kissingen in Bavaria, Germany, in 1921. The rise ofthe Nazi party in Germany, with its open anti-Semitism, prompted his parents to send himout of the country.

Steinberger emigrated to the United States at the age of 13,making the trans-Atlantic trip with his brother Herbert.Barnett Farroll cared for him as a foster child, theconnection was made by Jewish charities in the United States.During this period, Steinberger attended New Trier Township High School, in Winnetka, Illinois.

Steinberger obtained a bachelor's degree in Chemistryfrom the University of Chicago, in 1942. Shortly thereafter,he joined the Signal Corps at MIT. With the help of the
G.I. Bill, he returned to graduate studies at the University of Chicago in 1946, where he studied under Edward Tellerand Enrico Fermi. His Ph.D. thesis concerned the energyspectrum of electrons emitted in muon decay; his resultsshowed that this was a three-body decay, and implied theparticipation of "two" neutral particle in the decay(later idenfified as the electron and muon neutrinos).

Early Work

After receiving his doctorate,Steinberger attended the Institute for Advanced Studyat Princeton for a year. In 1949 he published a calculationof the lifetime of the neutral pion [ [http://www.slac.stanford.edu/spires/find/hep/www?j=PHRVA,76,1180 On the Use of subtraction fields and the lifetimes of some types of meson decay by J. Steinberger, in "Physical Review 76 (1949) p. 1180"] ] , which anticipated the study of anomalies in quantum field theory.

Following Princeton, Steinberger went to the Radiation Labat the University of California at Berkeley, where heperformed an experiment which demonstrated the productionof neutral pions and their decay to photon pairs. Thisexperiment utilized the 330 MeV synchrotron and the newly-inventedscintillation counters [ [http://www.slac.stanford.edu/spires/find/hep/www?j=PHRVA,78,802 Evidence For The Production Of Neutral Mesons By Photons by J. Steinberger, W.K.H. Panofsky and J. Steller, "Physical Review 78 (1950) p. 802"] ] .Despite this and other achievements, he was asked to leavethe Radiation Lab at Berekely due to his refusal to signthe so-called "Non-Communist Oath."

Steinberger accepted a faculty position at Columbia in 1950.The newly commissioned meson beam at Nevis Labsprovided the tool for several important experiments.Measurements of the production cross section of pions on variousnuclear targets showed that the pion has odd parity [ [http://www.slac.stanford.edu/spires/find/hep/www?j=PHRVA,82,958 Total cross-sections of pi-minus mesons on protons and several other nuclei by C. Chedester, P. Isaacs, A. Sachs and J. Steinberger, "Physical Review 82 (1951), p. 958"] ] .A direct measurement of the production of pions on a liquidhydrogen target, then not a common tool, provided the dataneeded to show that the pion has spin zero.The same target was used to observe the relative rare decayof neutral pions to a photon, an electron and a positron.A related experimentmeasured the mass difference between the charged and neutralpions based on the angular correlation between the neutralpions produced when the negative pion is captured by the protonin the hydrogen nucleus [The Mass Difference of Neutral and Negative pi Mesons by W. Chinkowsky and J. Steinberger,"Physical Review 93 (1954), p. 586"] . Other importantexperiments studied the angular correlation betweenelectron-positron pairs in neutral pion decays, and establishedthe rare decay of a charged pion to an electron and neutrino;the latter required use of a liquid-hydrogen bubble chamber [beta Decay of the Pion by G. Impeduglia, R. Plano, A. Prodell, N. Samios, M. Schwartz and J. Steinberger, "Physical Review Letters 1 (1958), p. 249"] .

Investigations of Strange Particles

In 1954-5, Steinberger contributed to the development of the bubble chamberwith the construction of a 15 cm device for use with the Cosmotron atBrookhaven. The experiment used a pion beam to produce pairs of hadronswith strange quarks in order to elucidate the puzzling production anddecay properties of these particles ["'Properties of Heavy UnstableParticles Produced by 1.3 BeV pi-minus Mesons"' by Budde, Chretien,Leitner, Samios, Schwartz and Steinberger "Physical Review 103 (1956)p. 1827"] . Somewhat later, in 1956, a 30 cm chamber outfitted withthree cameras was used in the discovery of the neutral Sigma hyperonand a measurement of its mass ["'Demonstration of the Existence ofthe Sigma-zero Hyperon and a Measurement of Its Mass" by E. Plano,N. Samios, M. Schwartz and J. Steinberger "Nuovo Cimento V (1957) p. 216"] .This observation was important for confirming the existence ofthe SU(3) flavor symmetry which hypothesizes the existence ofthe strange quark.

An important characteristic of the weak interaction is itsviolation of parity symmetry. This characteristic was establishedthrough the measurement of the spins and parities of many hyperons.Steinberger and his collaborators contributed several such measurementsusing large (75 cm) liquid-hydrogen bubble chambers and separatedhadron beams at Brookhaven. One example is the measurement of theinvariant mass distribution of electron-positron pairs produced inthe decay of Sigma-zero hyperons to Lambda-zero hyperons [Cynthia Alfet al., "Siena 1963 Conference Report, p. 205"] .

Neutrinos and the Weak Neutral Current

In the 1960s, the emphasis in the study of the weak interactionshifted from strange particles to neutrinos. Steinberger and
Schwartz built large spark chambers at Nevis Laband exposed them in 1961 to neutrinos produced in association with muonsin the decays of charged pions and kaons. They used the "AlternatingGradient Synchrotron" (AGS) at Brookhaven, and obtained a number of convincing events in which muons were produced, but no electrons [ [http://www.slac.stanford.edu/spires/find/hep/www?j=PRLTA,9,36 Observation of High-Energy Neutrino Reactions and The Existence of Two Kinds Of Neutrinos by G. Danby, J.M. Gaillard, Konstantin Goulianos, L.M. Lederman, Nari B. Mistry, M. Schwartz, J. Steinberger, "Physical Review Letters 9 (1962) p.36"] ] .This result, for which they received the Nobel Prize in 1988,proved the existence of a type of neutrino associatedwith the muon, distinct from the neutrino produced in beta decay.

tudy of CP Violation

The violation of CP (charge conjugation and parity) was establishedin the neutral kaon system in 1964. Steinberger recognized thatthe phenomenological parameter epsilon (ε) which quantifies the degree of CP violation could be measured in interference phenomena. In collaboration with Carlo Rubbia, he performedan experiment while on sabbatical at CERN during 1965 whichdemonstrated robustly the expected interference effect, andalso measured precisely the difference in mass of the short-livedand long-lived neutral kaon masses ["'KS and KL Interferencein the pi+pi- Decay Mode, CP Invariance and the KS-KL Mass Difference"'C. Alff-Steinberger et al "Physics Letters 20 (1966) p. 207"and "Physics Letters 21 (1966) p. 595"] .

Back in the United States, Steinberger conducted an experimentat Brookhaven to observe CP violation in the semi-leptonic decaysof neutral kaons. The charge asymmetry relates directly to theepsilon parameter, which was thereby measured precisely ["Measurementof the Charge Asymmetry in the Decay KL to pion electron neutrino"Bennett, Nygren, Saal, Steinberger and Sutherland"Physical Review Letters 19 (1967) p. 993] .This experiment also allowed the deduction of the phase of epsilon,and confirmed that CPT is a good symmetry of nature.

CERN

In 1968, Steinberg left Columbia University and accepted a position as a department director at CERN.He constructed an experiment there utilizing multi-wire proportionalchambers (MWPC), recently invented by Georges Charpak. TheMWPC's, augmented by micro-electronic amplifiers, allowed muchlarger samples of events to be recorded. Several results forneutral kaons were obtained and published in the early 1970's, including the observation of the rare decay of the neutral kaonto a muon pair, the time-dependence of the asymmetryfor semi-leptonic decays, and a more precise measurement of theneutral kaon mass difference. A new era in experimentaltechnique was opened.

These new techniques proved crucial for the first demonstration ofdirect CP-violation. A new experiment "NA31" at CERN was built in theearly 1980's using the CERN SPS 400 GeV proton synchrotron. Asidefrom banks of MWPC's and a hadron calorimeter, it featured a liquid-Argonelectromagnetic calorimeter with exceptional spatial and energy resolution.NA31 showed that direct CP violation is real ["'First Evidencefor Direct CP Violation" by H. Burkhardt et al., "Physics LettersB206 (1988) p. 169"] .

Nobel Prize in Physics

Jack Steinberger was awarded the Nobel Prize in Physics in the year 1988, "for the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino". He shares this prize with Leon M. Lederman and Melvin Schwartz. At the time, all three experimenters were at Columbia University.

The experiment used charged pion beams generated with the "Alternating Gradient Synchrotron" (AGS) at Brookhaven National Laboratory. The pions decayed to muons which were detected in front of a steel wall; the neutrinos 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 in Physical Review Letters in 1962 [ [http://www.slac.stanford.edu/spires/find/hep/www?j=PRLTA,9,36 Observation of High-Energy Neutrino Reactions and The Existence of Two Kinds Of Neutrinos by G. Danby, J.M. Gaillard, Konstantin Goulianos, L.M. Lederman, Nari B. Mistry, M. Schwartz, J. Steinberger, "Physical Review Letters 9 (1962) p.36"] ] .

He gave his Nobel medal to New Trier High School in Winnetka, Illinois (USA), of which he is an alumnus.

References

Publications

*Steinberger, J. & A. S. Bishop. [http://www.osti.gov/cgi-bin/rd_accomplishments/display_biblio.cgi?id=ACC0219&numPages=10&fp=N "The Detection of Artificially Produced Photomesons with Counters"] , Radiation Laboratory, University of California-Berkeley,United States Department of Energy (through predecessor agency the Atomic Energy Commission), (March 8, 1950).
*Steinberger, J., W. K. H. Panofsky & J. Steller. [http://www.osti.gov/cgi-bin/rd_accomplishments/display_biblio.cgi?id=ACC0220&numPages=19&fp=N "Evidence for the Production of Neutral Mesons by Photons"] , Radiation Laboratory, University of California-Berkeley,United States Department of Energy (through predecessor agency the Atomic Energy Commission), (April 1950).
*Panofsky, W. K. H., J. Steinberger & J. Steller. [http://www.osti.gov/cgi-bin/rd_accomplishments/display_biblio.cgi?id=ACC0221&numPages=44&fp=N "Further Results on the Production of Neutral Mesons by Photons"] , Radiation Laboratory, University of California-Berkeley,United States Department of Energy (through predecessor agency the Atomic Energy Commission), (Oct. 1, 1950).
*Steinberger, J. [http://www.osti.gov/cgi-bin/rd_accomplishments/display_biblio.cgi?id=ACC0222&numPages=58&fp=N "Experimental Survey of Strange Particle Decays"] , Columbia University, Nevis Laboratories,United States Department of Energy (through predecessor agency the Atomic Energy Commission), (June 1964).

External links

* [http://www.osti.gov/accomplishments/steinberger.html Biography and Bibliographic Resources] , from the Office of Scientific and Technical Information, United States Department of Energy
* [http://nobelprize.org/physics/laureates/1988/steinberger-autobio.html Autobiography (at the Nobel Prize web site)]
* [http://nobelprize.org/nobel_prizes/physics/ official web site for the Nobel Prize in Physics]
* [http://public.web.cern.ch/PUBLIC/en/People/Steinberger-en.html CERN web site for Jack Steinberger] ]