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1964Nobel Prize in Physics - 1980 Evidence for the 2π decay of the Κ20 Meson
J. H. Christenson, J. W. Cronin, V. L. Fitch, and R. Turlay
Phys. Rev. Lett. 13, 138 (1964)
More Information | Read Letter | K mesons were discovered and studied through the 1950s and, because of the odd way they decayed, came to be called "strange" particles and assigned a strangeness quantum number. The neutral Κ meson (Κ0), with strangeness +1, can mix through the weak interaction with its antiparticle the Κ0, with strangeness -1, to form the mass eigenstates ΚS0 and ΚL0. Both these eigenstates decay through the weak interaction into pions. It was known at the time of this Letter that the weak interaction violated parity P and charge conjugation C, but it was believed that it conserved charge parity CP. Conservation of CP requires that the ΚS0 meson can only decay into an even-pion state (which has CP = +1), and the ΚL0 only into an odd-pion state (CP = -1). This Letter presented experimental evidence that the ΚL0 meson (called Κ20 at the time) also has a small probability of decaying into 2 pions, so that the weak interaction violates charge parity as well.
For the discovery of CP violation in the decay of neutral K mesons, Cronin and Fitch were awarded the 1980 Nobel Prize in Physics.
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Broken Symmetry and the Mass of Gauge Vector Mesons
F. Englert and R. Brout
Phys. Rev. Lett. 13, 321 (1964)
More Information | Read Letter | Broken Symmetries and the Masses of Gauge Bosons
Peter W. Higgs
Phys. Rev. Lett. 13, 508 (1964)
More Information | Read Letter | Global Conservation Laws and Massless Particles
G. S. Guralnik, C. R. Hagen, and T. W. Kibble
Phys. Rev. Lett. 13, 585 (1964)
More Information | Read Letter | These Letters contain an explanation that shows how mass could arise in local gauge theories. Gauge symmetries explain how the strong and electroweak forces arise, but such symmetries forbid vector boson mass terms. The authors showed how gauge symmetries could be spontaneously broken in such a way that the vector bosons of the theory acquire mass. A number of earlier Physical Review papers foresaw different aspects of this mechanism. The Large Hadron Collider at CERN will be searching for a particle (generally called the “Higgs”) that will constitute evidence for these theories.
The 2004 Wolf Prize was awarded to Englert, Brout, and Higgs for their contributions to the theories.
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1963Nobel Prize in Physics - 2005 Photon Correlations
Roy J. Glauber
Phys. Rev. Lett. 10, 84 (1963)
More Information | Read Letter | This Letter first introduced Glauber’s treatment of the quantum properties of light and its interactions with atoms. He developed this extensively in articles in Physical Review, and presented seventeen(!) lectures on the subject at the 1964 Les Houches summer school (published in the book Quantum Optics and Electronics, Gordon and Breach, 1965). There was much disagreement over the need for a quantum treatment. Glauber argued that the then recent development of the laser and of detectors that could measure a single optical photon made more than a classical treatment essential. Ultimately his view prevailed, and was recognized with the 2005 Nobel Prize. (See also Phys. Rev. Focus 16, story 13.) |
Gravitational Field of a Spinning Mass as an Example of Algebraically Special Metrics
Roy P. Kerr
Phys. Rev. Lett. 11, 237 (1963)
More Information | Read Letter | In this Letter Kerr presented a new exact solution of the Einstein gravitational field equations, only the third such solution up to that time. The expression for the metric tensor, now known as the Kerr metric, describes the space-time geometry, called frame dragging, in the vicinity of an uncharged rotating point mass (or a black hole). It also describes, approximately, the geometry outside an extended rotating body such as the Earth. In spite of its seemingly impenetrable mathematics and terminology the paper was understood, appreciated, and built upon by physicists working in the field. An experimental test of predictions based on the metric has been a major goal of Gravity Probe B, a NASA/Stanford satellite mission launched in 2004, which collected data until 2005. (See also Physics News Update 820 #2.)
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1962Nobel Prize in Physics - 1988 Observation of High-Energy Neutrino Reactions and the Existence of Two Kinds of Neutrinos
G. Danby, J-M. Gaillard, K. Goulianos, L. M. Lederman, N. Mistry, M. Schwartz, and J. Steinberger
Phys. Rev. Lett. 9, 36 (1962)
More Information | Read Letter | This Letter reported an experiment that demonstrated a difference in neutrinos produced in the decay of π-mesons into muons, and neutrinos from those produced in β-decay, the decay of nuclei into electrons and neutrinos. The π-mesons were produced by a beam of protons striking a target; the π-mesons then decayed in flight into muons and neutrinos. After passing through shielding to remove all other particles the neutrinos interacted with the matter in the plates of an aluminum spark chamber, where they produced muons but not electrons. For this discovery of the muon neutrino and the development of the neutrino-beam method that made it possible the 1988 Nobel Prize was given to three of the authors of this Letter: Leon Lederman, Melvin Schwartz, and Jack Steinberger. |
Nobel Prize in Physics - 2002 Evidence for X Rays from Sources Outside the Solar System
Riccardo Giacconi, Herbert Gursky, Frank R. Paolini, and Bruno B. Rossi
Phys. Rev. Lett. 9, 439 (1962)
More Information | Read Letter | Riccardo Giacconi shared the 2002 Nobel Prize with Raymond Davis and Masatoshi Koshiba; Davis and Koshiba for the development of neutrino astronomy, and Giacconi for the discovery of cosmic x-ray sources. This Letter reports the first observation of an x-ray source outside the Solar System. The x-ray detector was launched on a rocket to look for x-ray emissions from the Moon; instead they found a bright source of soft x-rays in the constellation Scorpius. This source, now known as Scorpius X-1, is the brightest x-ray source in the sky after the Sun. It has since been identified as a neutron star in a binary-star system some 9,000 light years away. (See also Phys. Rev. Focus 10, story 18.) |
Coherent Light Emission from GaAs Junctions
R. N. Hall, G. E. Fenner, J. D. Kingsley, T. J. Soltys, and R. O. Carlson
Phys. Rev. Lett. 9, 366 (1962)
More Information | Read Letter | This Letter reports the first observation of laser action in a solid-state device; it was followed (very) closely by groups at IBM, Lincoln Laboratory of MIT, and by others at General Electric. All of the latter publications appeared in the first volume of Applied Physics Letters. Further development of diode lasers, producing high collimation and intensity and with ease of fabrication, ultimately made possible the optical storage of data, music, and video. |
1961Generation of Optical Harmonics
P. A. Franken, A. E. Hill, C. W. Peters, and G. Weinreich
Phys. Rev. Lett. 7, 118 (1961)
More Information | Read Letter | After the successful demonstration of the ruby laser by Maiman it was realized that focusing of the laser beam could produce a very strong electric field in a dielectric. This clearly written Letter is widely recognized as a pioneering demonstration of a nonlinear optical effect, where the intense laser beam produces a second beam at twice the laser light frequency. The paper contains a theoretical outline and experimental example of the second harmonic generation of light in quartz, and it is still heavily read and cited. |
Experimental Evidence for Quantized Flux in Superconducting Cylinders
Bascom S. Deaver and William M. Fairbank
Phys. Rev. Lett. 7, 43 (1961)
More Information | Read Letter | Theoretical Considerations Concerning Quantized Magnetic Flux In Superconducting Cylinders
N. Byers and C. N. Yang
Phys. Rev. Lett. 7, 46 (1961)
More Information | Read Letter | In the first of these two Letters, Deaver and Fairbank reported their observation that the magnetic flux trapped in hollow superconducting tin cylinders was quantized in units of hc/2e. Earlier, in 1950, Fritz London had predicted this quantization effect but in units of hc/e, twice the result of Deaver and Fairbank. In the second Letter Byers and Yang interpreted Deaver and Fairbank's results. They showed that the quantization of magnetic flux through a superconducting ring is closely related to the Meissner effect, in which a superconductor expels magnetic flux from its interior, and that the factor of 1/2 is an indication of the Bardeen-Cooper-Schrieffer pairing of the electrons in the superconducting state. |
1960Apparent Weight of Photons
R. V. Pound and G. A. Rebka
Phys. Rev. Lett. 4, 337 (1960)
More Information | Read Letter | After the discovery in 1958 of recoil free absorption of gamma rays in iridium by Rudolf Mössbauer there was much interest in performing experiments with different isomers. Attention focused on Fe 57, with the expectation that an experiment to detect the effect of gravity on gamma radiation, as predicted by Einstein in 1911, could be carried out. Several groups made efforts to observe the resonance in Fe 57, and once this was accomplished there was an explosion of experiments that led to the observation and application of nuclear hyperfine magnetic and quadrupole splittings and the chemical isomer shift. In this Letter Pound and Rebka describe the results of their experiment, which was the most definitive of the efforts to observe gravitational effects. They had to account for many possible differences between the source and the absorber that could mask the gravitational shift of the frequency, and the results were in agreement with Einstein's prediction. (See also Phys. Rev. Focus 16, story 1.) |
Nobel Prize in Physics - 1973 Energy Gap in Superconductors Measured by Electron Tunneling
Ivar Giaever
Phys. Rev. Lett. 5, 147 (1960)
More Information | Read Letter | Electron Tunneling Between Two Superconductors
Ivar Giaever
Phys. Rev. Lett. 5, 464 (1960)
More Information | Read Letter | Ivar Giaever shared the 1973 Nobel Prize with Leo Esaki and Brian Josephson; Esaki for the junction diode based on tunneling in semiconductors, and Josephson for the tunneling of BCS electron pairs between superconductors. The two Letters shown here were the basis for the award to Giaever. In these experiments he demonstrated the change in the electron density of states (the appearance of a gap) on going from the normal to the superconducting state, in agreement with the BCS theory. |
1959Lattice Vibrations in Silicon and Germanium
B. N. Brockhouse
Phys. Rev. Lett. 2, 256 (1959)
More Information | Read Letter | Bertram Brockhouse and Clifford Shull shared the physics Nobel Prize in 1994 for their researches using neutron scattering. Brockhouse was cited for his experiments using inelastic scattering, which enabled the study of excitations in solids, while Shull received the award for his elastic scattering studies, which gave information on structure, both magnetic and physical, of condensed matter. It is difficult to cite a single paper that led to this prize, but we give here an example of the work of Brockhouse that uses the techniques (particularly the "triple axis spectrometer") for which he was cited. The phonon spectra of silicon and germanium are of particular interest because of their considerable practical as well as theoretical importance. |
Calculation of Partition Functions
J. Hubbard
Phys. Rev. Lett. 3, 77 (1959)
More Information | Read Letter | This very mathematical Letter has had a significant impact in all areas of physics and chemistry. The formalism enables the calculation of the thermodynamic properties of quantum-mechanical systems in condensed matter and in quark matter. Hubbard outlines a rederivation of results for the correlation energy of an electron gas, of the Bardeen-Cooper-Schrieffer theory of superconductivity, and of correlations in nuclear matter. The mathematical techniques have also made possible numerical Monte Carlo calculations of the properties of quantum-mechanical systems. After nearly fifty years it is still very frequently downloaded from the APS PROLA archive. |
1958Element No. 102
A. Ghiorso, T. Sikkeland, J. R. Walton, and G. T. Seaborg
Phys. Rev. Lett. 1, 18 (1958)
More Information | Read Letter | This Letter announced the first synthesis of an isotope of the transuranic element 102 and described a then-new technique to identify high-Z elements. A year earlier researchers at the Nobel Institute in Sweden had claimed to have discovered an isotope of this element with a 10-minute half-life and proposed the name "nobelium" for it [P. R. Fields et al., Phys. Rev. 107, 1460 (1957)]. This claim could not be confirmed, either by these authors at UC Berkeley [ PRL 1, 17 (1958)] or by a group at the Joint Institute for Nuclear Research in Dubna, Russia. The Dubna group did confirm the Berkeley group's work and further confirming experiments were done at Berkeley in 1966. The Berkeley group eventually got credit for the discovery and the right to name it, but recommended that the name nobelium be retained. |
Two-Fluid Model of Superconductivity
John Bardeen
Phys. Rev. Lett. 1, 399 (1958)
More Information | Read Letter | The famous Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity, for which the Nobel prize was awarded in 1972, was announced in 1957, before the creation of Physical Review Letters. Many papers following up on that theory subsequently appeared in PRL. In this paper Bardeen raises the question of the oft-made comparison between superconductivity and the superfluidity of liquid helium 4. The phenomenological two fluid (normal and superfluid) model of helium 4 introduced by Fritz London was applied to superconducting electrons as well, but the BCS theory justification for this was not obvious. Bardeen here shows that there is a basis for that comparison, based on reasonable approximations. |
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