Frank Close neutrino, a subatomic particle.

por | 28 mayo, 2024
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SUMMARY

Frank Close, a physicist, discusses the history of the neutrino, a subatomic particle.

IDEAS:

  • Neutrinos are the most common and weirdest particles in the universe.
  • Neutrinos can pass through the Earth like a bullet through fog.
  • Most neutrinos are remnants of the Big Bang, traveling for over 13 billion years.
  • Radioactive atoms trapped in Earth’s crust were the first clues to neutrinos’ existence.
  • Röntgen’s discovery of X-rays inspired the work that led to radioactivity.
  • Becquerel discovered radioactivity by accident due to overcast weather.
  • Marie Curie discovered radium, which emits energy spontaneously.
  • Rutherford identified three forms of radiation: alpha, beta, and gamma.
  • Alpha particles are pieces of atomic nuclei, consisting of two protons and two neutrons.
  • Beta radiation consists of electrons created from energy released in nuclear transmutation.
  • Gamma rays are particles of light with shorter wavelengths than visible light.
  • Einstein’s theory of relativity linked energy and mass, explaining radioactivity.
  • Beta decay violates energy conservation unless an additional particle is emitted.
  • Pauli proposed an invisible particle, the «neutron,» to explain the energy anomaly in beta decay.
  • The neutron was later discovered by Chadwick, but it’s heavier than the «neutron» in beta decay.
  • Fermi renamed Pauli’s particle the «neutrino,» meaning «little neutron.»
  • The Solvay Conference of 1933 focused on nuclear physics and helped Fermi develop his theory of beta decay.
  • Fermi’s theory implied that a neutrino could bump into a neutron and convert it into a proton and an electron.
  • Bethe and Peierls calculated that neutrinos have a very small chance of interacting with matter.
  • Pontecorvo realized that, despite the small chance of interaction, a large enough source could make detection possible.
  • Nuclear reactors produce a vast number of neutrinos, making them ideal for detection.
  • Pontecorvo proposed using a vat of chlorine to capture neutrinos, which would be converted to radioactive argon.
  • Ray Davis, inspired by Pontecorvo’s paper, attempted to capture neutrinos from a reactor, but failed because it produced antineutrinos.
  • Cowan and Reines successfully detected neutrinos from a nuclear reactor using «inverse beta decay,» which produces a neutron and a positron.
  • The Sun produces neutrinos through nuclear fusion, primarily through the proton-proton (pp) chain.
  • The CNO cycle, which produces neutrinos, is less important in the Sun than the pp chain.
  • The production of beryllium-7 in the Sun was found to be much easier than previously thought, leading to a resurgence of hope for detecting solar neutrinos.
  • To reduce the background from cosmic rays, Davis built his detector 1480 meters underground in the Homestake gold mine.
  • Mottelson realized that solar neutrinos could excite chlorine, making the detection process 20 times easier.
  • The Homestake experiment was funded by Brookhaven National Laboratory, not by a federal agency.
  • Bahcall calculated that Davis’s experiment should detect 7.5 SNUs (solar neutrino units) of neutrinos from the Sun.
  • The SNU is a measure of the capture rate of neutrinos, which is extremely small due to the low probability of interaction.
  • Davis’s experiment detected only 3 SNUs, creating the «solar neutrino problem.»
  • The «swimming pool improvement» reduced the background noise in Davis’s experiment, making it more sensitive.
  • The solar neutrino problem led to the development of new experiments, such as GALLEX and SAGE, using gallium detectors.
  • Gallium detectors are sensitive to lower-energy neutrinos, including those from the pp chain.
  • Kamiokande, a water-detector experiment designed to search for proton decay, was repurposed to detect solar neutrinos.
  • Kamiokande detected neutrinos from Supernova 1987A, the first time neutrinos were observed from outside our galaxy.
  • SuperKamiokande, an upgrade of Kamiokande, confirmed the atmospheric neutrino anomaly, showing that muon-neutrinos disappear over long distances.
  • Pontecorvo had predicted neutrino oscillations in 1968, suggesting that neutrinos can change flavor as they travel.
  • The MSW effect, proposed by Wolfenstein, Mikheyev, and Smirnov, explained how matter can amplify neutrino oscillations.
  • SNO, a heavy water detector, confirmed that electron-neutrinos from the Sun oscillate into other flavors, resolving the solar neutrino problem.
  • The discovery of neutrino oscillations proved that neutrinos have mass, a major deviation from the Standard Model.
  • KamLAND, a liquid scintillator detector, observed neutrino oscillations from nuclear reactors.
  • MINOS, an experiment using a neutrino beam from Fermilab, confirmed neutrino oscillations and is measuring the mass difference between neutrino flavors.
  • The search for solar neutrinos has led to the development of neutrino astronomy, using underground detectors to observe neutrinos from cosmic sources.
  • AMANDA and ICECUBE, detectors in the Antarctic ice, search for high-energy neutrinos from cosmic rays.
  • Neutrinos provide a new window on the universe, enabling scientists to study objects obscured by gas and dust.
  • The discovery of neutrino oscillations has opened up new possibilities in physics, potentially leading to the discovery of new particles and forces.

INSIGHTS:

  • Neutrinos, once thought to be massless and undetectable, are now known to have mass and to oscillate between different flavors.
  • The discovery of neutrino oscillations has challenged the Standard Model of particle physics.
  • Neutrino astronomy has emerged as a new field of science, providing insights into the inner workings of stars and other cosmic objects.
  • The pursuit of solar neutrinos has led to a deeper understanding of the Sun, the fundamental processes of nuclear fusion, and the nature of neutrinos themselves.
  • Serendipity, chance encounters, and unforeseen discoveries have played a crucial role in the history of neutrino research.

QUOTES:

  • «With X-rays, which penetrate much more than ordinary light, you can see inside your hand. With neutrinos, which penetrate much more even than X-rays, you can look inside the Sun.» – Ray Davis
  • «There is no practically possible way of observing the neutrino.» – Hans Bethe and Rudolf Peierls
  • «It is possible that the proper mass of neutrinos be zero…We know nothing about the interaction of neutrinos with the other particles of matter or with photons.» – Wolfgang Pauli
  • «Every solution to the issue must be discussed. Thus, dear radioactive people, look and judge.» – Wolfgang Pauli
  • «Only the one who dares can win.» – Wolfgang Pauli
  • «It seems to me plausible that neutrinos have a spin 1/2.» – Wolfgang Pauli
  • «I feel like dancing, I’m so happy.» – John Bahcall
  • «If you can measure something accurately enough, you have a chance of discovering something important. The history of astronomy shows that it is very likely that what you discover will not be what you were looking for.» – John Bahcall
  • «Everything comes to him who knows how to wait.» – Wolfgang Pauli
  • «What Nature does not forbid, will happen.» – Murray Gell-Mann
  • «I have postulated a particle that cannot be detected.» – Wolfgang Pauli
  • «Who ordered that?» – Isadore Rabi
  • «Neutrino detection was not a popular activity in 1952.» – Fred Reines
  • «I was advised to go to the library, do some reading and choose a project of my own, whatever appealed to me.» – Ray Davis
  • «It starts to be really interesting! It would be nice if all this ends with something unexpected from the point of view of [neutrinos].» – Bruno Pontecorvo

HABITS:

  • Ray Davis: Reading habits, researching and choosing own projects.
  • Bruno Pontecorvo: Writing papers, proposing experiments, questioning established theories.
  • John Bahcall: Problem-solving, reading astrophysics literature, applying quantum mechanics to astrophysical phenomena.
  • Fred Reines: Pursuing difficult experiments, setting ambitious goals, collaborating with others.
  • Jack Steinberger: Seeking clarity in complex problems, proposing experimental tests, working independently.
  • Leon Lederman: Lunchtime discussions, seeking experimental confirmation of theories.
  • Masatoshi Koshiba: Building large-scale experiments, leading international collaborations.
  • Wolfgang Pauli: Critiquing theories, proposing new particles.

FACTS:

  • The Sun’s energy comes from nuclear fusion, primarily the pp chain.
  • The CNO cycle is less important in the Sun than the pp chain.
  • The Sun emits about 66 billion neutrinos per square centimeter per second.
  • Neutrinos interact with matter through the weak force, which is very weak.
  • Neutrinos oscillate between different flavors, which requires them to have mass.
  • The MSW effect explains how matter can amplify neutrino oscillations.
  • There are three known flavors of neutrinos: electron, muon, and tau.
  • Supernovae are a major source of neutrinos, releasing vast amounts of energy.
  • Neutrinos from Supernova 1987A were the first detected from outside our galaxy.
  • Neutrino astronomy uses underground detectors to observe neutrinos from distant objects.
  • The Earth’s magnetic field influences the behavior of cosmic rays and atmospheric neutrinos.
  • Nuclear reactors produce antineutrinos, which can be used to study neutrino oscillations.
  • Neutrinos have very small masses, much smaller than the electron’s mass.

REFERENCES:

  • Books:
    • Lucifer’s Legacy by Frank Close
    • Inward Bound by A Pais
    • Atoms in the Family by Laura Fermi
    • Rutherford – Simple Genius by D Wilson
    • The God Particle by L Lederman and D Teresi
    • The Strangest Man by G Farmelo
    • Antimatter by Frank Close
    • Blinded by the Light by John Gribbin
    • The Particle Odyssey by Frank Close, Michael Marten, and Christine Sutton
    • Particle Physics: A Very Short Introduction by Frank Close
  • Journals:
    • Physical Review
    • Physical Review Letters
    • Nature
    • Astrophys. J Letters
    • Astrophys. J
    • Nuovo Cimento
    • Zeitschriftfur Physik
    • Physics Letters
    • Soviet Journal of Physics
    • Reviews of Modern Physics
    • Ann. Rev. Nucl. Science
    • Prog. Theor. Phys.
    • Nuclear Physics
    • Mon. Not. Royal Astronomical Society
  • Conferences:
    • Solvay Conference
    • International Conference on Stellar Evolution
    • International Conference on High Energy Physics
  • Organizations:
    • Brookhaven National Laboratory
    • Los Alamos National Laboratory
    • Atomic Energy Commission
    • CERN
    • Fermilab
    • National Science Foundation
    • US Department of Energy
    • Russian Academy of Sciences
    • Atomic Energy of Canada Ltd
    • Chicago Bridge and Iron Company
    • Frontier Chemical Company
    • Anaconda Copper Mine
    • Homestake Gold Mine
    • Sunshine Mine
    • Neils Bohr Institute
    • Institute for Advanced Study
    • Institute for Space Studies
    • Naval Research Laboratory
    • MIT radiation laboratory
    • Hanford Engineering Works
    • Savannah River nuclear reactor
  • Other:
    • Tomorrow’s World
    • Time magazine
    • Nova on PBS
    • AMANDA
    • ICECUBE
    • ANTARES
    • NESTOR
    • KamLAND
    • MINOS
    • SAGE
    • GALLEX
    • SuperKamiokande
    • Kamiokande
    • IMB

ONE-SENTENCE TAKEAWAY

The pursuit of the elusive neutrino, a fundamental particle with surprising properties, has revolutionized our understanding of the universe.

RECOMMENDATIONS:

  • Read books and articles about the history of neutrino research.
  • Explore the world of particle physics and the Standard Model.
  • Learn more about neutrino astronomy and its potential for discovery.
  • Support research in fundamental physics, which has led to transformative discoveries.
  • Appreciate the role of serendipity and unexpected discoveries in scientific progress.
  • Embrace curiosity and a willingness to challenge established theories.
  • Understand the importance of precision measurements and their impact on scientific knowledge.
  • Reflect on the long history of scientific inquiry and the interconnectedness of different fields.
  • Recognize the dedication and perseverance of scientists who have made significant contributions to our understanding of the universe.
  • Be aware of the political and social factors that can influence scientific research.
  • Consider the potential impacts of technological advancements on our understanding of the cosmos.
  • Explore the ethical implications of scientific discoveries and their applications.
  • Support public outreach and education in science to inspire future generations.
  • Seek opportunities to engage in scientific research and contribute to the advancement of knowledge.
  • Be open to the possibility of new and unexpected discoveries.
  • Celebrate the triumphs of scientific inquiry and the human quest for knowledge.