vol IV chap 13 sect 2
Previous: 13.1. Steps in the development of Nuclear Physics.
13.2. Timeline of the main developments in high energy physics.¶
In what follows, according to the documents called WORK published in the Nobel Prize web page, we indicate the year each laureate started working on the subject, introduced a new concept or procedure, made a critical discovery, initiated a long-term project or started a pioneering contribution to the development or invention of a practical instrument or an experimental setting.
Around 1895 Wilhelm Conrad Röntgen (1845-1923) discovered X-rays when he was experimenting with a Crookes tube. This type of radiation was generated because fast-moving electrons suddenly decelerated during their collision and interaction with the target anode.
In 1896 Antoine Henri Becquerel (1852-1908) discovered spontaneous radioactivity when he analyzed the image formed in a sensitive photographic plate by a sort of radiation produced by certain salts of uranium, despite of covering the plate with aluminum foils; such radiation also made air conduct electricity.
In 1897 Joseph John Thomson (1856-1940) showed that cathode rays consisted of particles that conduct electricity and were part of atoms: the electrons.
In 1898 the Curies Pierre (1859-1906) and Marie (1867-1934) provided experimental proof of the existence of radioactive elements such as polonium and radium. They also examined many substances and minerals for signs of radioactivity as in actinium. They described the radioactive properties of these elements and demonstrated that radioactivity was a specific atomic property.
In 1899 Ernest Rutherford (1871-1937) demonstrated that there were at least two distinct types of radiation emanating from a radioactive element: alpha radiation and beta radiation, afterwards interpreted respectively as ionized helium atoms He-4 (composed of two protons and two neutrons) and as electrons.
In 1902 Rutherford and Frederick Soddy (1877-1956) proposed a transmutation theory explaining the transformation of elements. In between 1908 and 1913, Hans Geiger (1882-1945) and Ernest Marsden (1989-1970) performed a series of experiments for testing Thomson atomic model called the “plum pudding”.
In 1910 Marie Curie (1867-1934) produced radium as a pure metal and also worked on the theory of atomic radioactive transformations.
In 1910 Robert Andrews Millikan (1868-1953) determined the magnitude of the electron’s charge by experimenting with small electrically charged drops subjected to the downward force of gravity and the upward attraction of an electrical field.
In 1911 Charles Thomson Rees Wilson (1869-1959) constructed a cloud chamber which was a glass container with air and water vapor; an increase in the volume of this mixture of air and water vapor produced small water drops. If the air contained electrically charged particles—ions—then the droplets surrounded these charges. The traces left by ionizing radiation and particles that pass through the chamber become visible to be photographed.
In 1919 Rutherford produced transmutations of atomic nuclei by bombarding nitrogen with helium nuclei obtained from a radium source. This transformation of nitrogen into oxygen was the first case of transmutation of elements by external means, the dream of alchemists.
In 1919 Francis William Aston (1877-1945) developed the mass spectrograph and build a map of different isotopes.
In 1922 Arthur Holly Compton (1892-1962) directed X-ray photons onto a metal surface and observed that the X-rays’ wavelength increased because some of the incident photon energy was transferred to the electrons, confirming that electromagnetic radiation could be described as photon particles.
In 1924 Prince Louis-Victor Pierre Raymond de Broglie (1892-1987) proposed that electrons could be understood both as particles and as waves, meaning that particles have an associated wave function describing their propagation and interactions.
In 1925 Wolfgang Pauli (1900-1958) formulated the exclusion principle, which implies that no two electrons in an atom could have identical sets of quantum numbers.
In 1927 Clinton Joseph Davisson (1881-1958) and George Paget Thomson (1892-1975) demonstrated, independently of one another, that electrons could be described as waves and present diffraction patterns.
In 1929 Ernest Orlando Lawrence (1901- 1958) started thinking in the construction of a cyclotron for accelerating protons to high velocities.
In 1932 James Chadwick (1891-1974) experimentally confirmed the existence of neutrons as a new fundamental building-stone of matter. He also determined the neutron mass and the atomic weights of some elements.
In 1932 Carl David Anderson (1905-1991) discovered of the positron: a particle with a similar mass as the electron and a positive charge, confirming Dirac prediction about the existence of antimatter.
In 1932 Patrick Maynard Stuart Blackett (1897-1974) in collaboration with Giuseppe Occhialini (1907-1993) connected a cloud chamber to a Geiger counter and detected the passage of particles. They also described how pairs of electrons and positrons could be formed out of photons. Blackett developed both the method and the apparatus.
In 1932 John Douglas Cockcroft (1897-1967) and Ernest Thomas Sinton Walton (1903-1995) bombarded lithium with high velocity protons, causing their nuclei to split and to produce two alpha particles. This was the first nuclear transmutation produced by artificial acceleration of particles under human controls.
In 1933 Eugene Wigner (1902-1995) discovered that the force binding the nucleons together is weak at great distances and strong at short distances. The force between two nucleons is the same, regardless of whether they are protons or neutrons. Wigner also show that most essential properties of the nuclei follow from generally valid symmetries of the laws of motion.
In 1934 Frédéric Joliot (1900-1958) and Irène Joliot-Curie (1897-1956) bombarded a thin piece of aluminum with alpha particles obtained from polonium and discovered that the radiation from the aluminum continued even after the source of radiation was removed. They created artificially the first radioactive element when aluminum atoms were converted into a radioactive isotope of phosphorus.
In 1934 Enrico Fermi (1901-1954) and collaborators observed that when neutrons were used as projectiles and slowed down by a shield of paraffin, the interaction rate with nuclei increases. Fermi discovered radioactivity induced by neutrons and applied it to 22 different elements. Fermi also obtained nuclear synthesis and produced two new elements: Ausenium and Hesperium, corresponding to atomic numbers 93 and 94.
In 1934 Hideki Yukawa (1907-1981) predicted the existence of a new particle, the meson, responsible of the strong nuclear force that maintained together protons and neutrons inside the atomic nucleus. The meson has a mass of nearly 200 times the mass of an electron, it is exchanged between nucleons, and when transformed it generates an electron and a neutrino, a very light particle without charge that was proposed in 1930 by Wolfgang Pauli (1900-1958).
In 1938 and 1939 Hans Albrecht Bethe (1906-2005) revealed how the Sun behaves like a giant nuclear reactor in which two kinds of nuclear reactions produce energy.
In 1939 Otto Hahn (1879-1968) in collaboration with Fritz Strassman (1902-1980) irradiated uranium with neutrons and created barium. Hahn received this Prize “for his discovery of the fission of heavy nuclei”.
In 1946 Clifford G. Shull (1915-2001) determined the structure of different molecules and materials using beams of neutrons created in a nuclear reactor. Shull was interested on where the atoms “are” (their structure).
In 1947 Cecil Frank Powell (1903-1969) discovered that the reaction of incident cosmic ray particles with atomic nuclei, as detected in a photographic emulsion, produced other short-lived particles: the pi-mesons.
In 1948 Maria Goeppert Mayer (1906-1972) wrote the paper On closed shells in nuclei, when she collected the empirical evidence pointing out the significance of the magic numbers.
During 1948, working through a renormalization procedure, Sin-Itiro Tomonaga (1906-1979) interpreted the splitting of degenerated energy levels within the hydrogen atom (the Lamb shift), Julian Schwinger (1918-1994) reformulated the theory to explain that he electron’s magnetic moment proved to be somewhat larger than expected, and Richard P. Feynman (1918-1988) created a new version of quantum electrodynamics introducing graphical procedure for the calculation of interaction probabilities (the Feynman diagrams).
In 1949 J. Hans D. Jensen (1907-1973) developed a model in which nucleons were distributed in shells with different energy levels, despite the fact that individual nucleons moved freely in an averaged potential.
During 1950 Bertram N. Brockhouse (1918-2003) worked on the development of the neutron diffraction technique and elaborated a chart of properties of molecules and materials. Brockhouse was interested on what the atoms “do” (their dynamics).
In 1950 Robert Hofstadter (1915-1990) started his studies on electron scattering in atomic nucleus by analyzing the distribution of charge and magnetism inside the nucleons. He also investigated the distribution bombarding the nucleus with fast electrons and made accurate measurements in the nuclei of the magnetic moments of protons and neutrons.
In 1950 Luis Walter Alvarez (1911-1988) introduced improvements in the bubble chamber by using liquid hydrogen and made new measurement systems and computer-based methods for analyzing large quantities of data of importance in the discovery of previously unknown fundamental particle resonances.
Since 1950 Frederick Reines (1918-1998) in collaboration with Clyde Cowan (1919-1974) were experimenting with radiation coming from a nuclear reactor and discovered neutrinos.
In 1950 James Rainwater (1917-1986) postulated that the atomic nucleus could be distorted and that certain nuclei had not spherical symmetry but were deformed as an ellipsoid because the valence nucleons influenced the shape of the inner nucleus.
In 1952 Donald Arthur Glaser (1926-2013) invented the bubble chamber as an instrument for observing the tracks produced by charged particles when they pass through a chamber filled with a liquid at near-boiling point. When the pressure inside the chamber is reduced, strings of bubbles are formed around these charged atoms and afterwards their corresponding tracks can be photographed and analyzed.
In the years 1952-1953 Aage Niels Bohr (1922-2009) and Ben Roy Mottelson (1926-2022), they proved that the position of energy levels in certain nuclei could be explained by the assumption that they form a rotation spectrum produced by the coupling of oscillations of the nuclear surface to the movements of the individual nucleons.
In 1953 Murray Gell-Mann (1929-2019) published the first of a series of papers indicating how to classify the elementary particles and their interactions (the Eightfold Way).
In 1955 Emilio Gino Segrè (1905-1989) and Owen Chamberlain (1920-2006) confirmed the existence of the proton’s antiparticle, the antiproton.
In 1956 Chen Ning Yang (1922) and Tsung-Dao (T.D.) Lee (1926) proposed that the left-right symmetry law is violated by the weak interaction. This was in contradiction with the assumption that the same physical laws apply where right and left were reversed, and matter was replaced by antimatter.
In 1958 Rudolf Ludwig Mössbauer (1929-2011) discovered the resonance absorption of gamma radiation in atoms embedded in a crystal structure and developed a new experimental method for the investigation of the inner structure of nuclei and nucleons. He observed that in a gas a recoil effect occurs when an atom emits a photon.
In 1960 Sheldon Lee Glashow (1932), Abdus Salam (1926-1996) and Steven Weinberg (1933-2021) independently developed a theory in which the new concept of the electroweak force was introduced, unifying the weak and the electromagnetic interactions between elementary particles.
In 1960 Raymond Davis Jr. (1914-2006) showed that the sun's energy originates from nuclear reactions in which hydrogen atoms combine with helium atoms to produce neutrinos.
Beginning 1960 Riccardo Giacconi (1931-2018) started studying emission of X-rays from stars and galaxies by means of telescopes in satellites.
In 1960, Yoichiro Nambu (1921-2015) formulated a mathematical theory for understanding spontaneous symmetry violations in subatomic physics.
In 1962 Leon M. Lederman (1922-2018), Melvin Schwartz (1932-2006) and Jack Steinberger (1921-2020) provided experimental evidence of the existence of a new type of neutrino, the muon neutrino.
In 1964 James Watson Cronin (1931-2016) and Val Logsdon Fitch (1923-2015) experimentally found that the matter-antimatter symmetry is violated when the neutral K-meson decays. They discovered that reactions going backward in time are not identical to those going forward meaning that there is an observed matter–antimatter asymmetry in the universe.
In 1964 François Englert (1932) and Robert Brout (1928-2011) and Peter W. Higgs (1929) proposed independently the theory of how particles acquire mass.
In 1964, Roger Penrose (1931) proposed critical mathematical tools to describe black holes. He showed that Einstein’s general theory of relativity means the formation of black holes and described black holes as a singularity where all known laws of nature dissolve.
In 1968 Georges Charpak (1924-2010) invented a multiwire proportional chamber for detecting very rare particle interactions. The entrance of particles in the chamber produced two effects: the liberation in cascade of electrons and the generation of currents in many thin, parallel wires arranged in a plane between two cathode planes.
Around 1970 Jerome I. Friedman (1930), Henry W. Kendall (1926-1999) and Richard E. Taylor (1929-2018) started a series of experiments with high-energy electrons colliding with protons and neutrons. Their results supported the theory that quarks are the building blocks of protons and neutrons and that the binding of them is due to the action of the bosons called gluons.
In the early 1970s, Gerardus t'Hooft (1946) and Martinus J.G. Veltman (1931-2021) formulated and tested a mathematical theory that explained the quantum structure of electroweak interaction.
In 1972, Makoto Kobayashi (1944) and Toshihide Maskawa (1940-2021) provided a mathematics-based explanation of the discovery that the decay of certain particles (kaons) was asymmetrical.
In 1973 David J. Gross (1941), H. David Politzer (1949) and Frank Wilczek (1951) postulated the existence of a property called asymptotic freedom. They proposed the mathematical framework called Quantum ChromoDynamics (QCD): the theory of the strong interaction between quarks mediated by gluons.
In 1974 Burton Richter (1931-2018) and Samuel Chao Chung Ting (1936) independently of each other, discovered a new heavy particle (J/psi) and proved experimentally the existence of the fourth quark, the “charm”.
In a series of experiments from 1974 to 1977 Martin L. Perl (1927-2014) discovered a new particle—the tau lepton. The experiments consisted in producing frontal collisions between electrons and their antiparticles, positrons.
Since 1980 Masatoshi Koshiba (1926-2020) measured the effects produced by neutrinos. When neutrinos pass through a tank of water inside a mine, they interact with atomic nuclei in the water and release an electron, creating small flashes of light to be detected by photomultipliers and then counted.
In 1983 Carlo Rubbia (1934) proposed and led experiments that, by allowing protons and antiprotons to collide at very high speeds, showed the existence of W and Z particles. Collaborating with him, Simon van der Meer (1925-2011) developed a method to accumulate a large number of energetic antiprotons in an accelerator ring. Rubbia developed the idea and van der Meer made it feasible.
Since the 1990s and for almost thirty years, Reinhard Genzel (1952) and Andrea Ghez (1965) they have developed and refined techniques for mapping the orbits of the brightest stars that are closest to the center of our galaxy.
In 1998 Takaaki Kajita (1959) built the Super-Kamiokande detector in a mine in Japan and discovered that neutrinos switch their identities before arriving. Neutrinos have been created in reactions between cosmic rays and the Earth’s atmospheres; however, the measurements showed that up to two thirds of the calculated amount was missing. This was explained in terms of neutrinos oscillations whose existence might imply that neutrinos do have very small mass.
Since 2000 Arthur B. McDonald (1943) made measurements in a mine in Canada for studying neutrinos created in nuclear reactions in the Sun. Deviations in such measurements showed that in coming the neutrinos were having mid-flight metamorphosis switching between three different types. As the Standard Model is based on neutrinos lacking mass and the oscillation of neutrinos implies that they have mass, that model must be revised.
In 2012, two experiments conducted at the CERN laboratory confirmed the existence of the Higgs particle. Two research groups of some 3,000 scientists each, managed to extract the Higgs particle from billions of particle collisions in the LHC (Large Hadron Collider).
Next: 13.3. Levels of operation of the mechanisms of knowing.