Neutrinos and Beyond New Windows on Nature (2003) / Chapter Skim
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2 Science Overview: Neutrinos and Beyond
2 Science Overview: Neutrinos and Beyond
Pages 9-21
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From page 9... ...
In 1956, Frederick Reines and his team detected neutrinos produced by a powerful nuclear reactor in Savannah River, South Carolina. He was awarded the Nobel Prize in physics for this discovery.
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From page 10... ...
have even revealed physics beyond the Standard Model of particle physics. Studying and understanding neutrino mass and oscillation provide a unique view into how the forces and particles are unified.
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From page 11... ...
Recent experiments have shown that neutrinos do in fact have mass, and that they can transform into one another. Figure courtesy of Paul Nienaber and Andrew Finn, BooNE Collaboration.
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From page 12... ...
, as shown by the sinusoidal curves alongside the scales. The detailed properties of neutrino oscillations are important to understanding how the Standard Model particles interact and how galaxies and the universe work.
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From page 13... ...
The advent of intense beams of neutrinos produced by particle accelerators quickened the pace of neutrino research and discoveries. First came the discovery of a second type of neutrino by Leon Lederman, Melvin Schwartz, and Jack Steinberger in a pioneering neutrino experiment at Brookhaven National Laboratory, for which they received the Nobel Prize in physics in 1988.
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From page 14... ...
For the three known neutrino types, there are only two independent mass differences; however, the absolute scale of neutrino mass remains undetermined. Two other recent discoveries mysterious flashes of gamma rays, which occur about once a day, and photons from distant galaxies with a trillion times the energy of visible light suggest that there are observable astrophysical sources of neutrinos in addition to the Sun and supernovae (see Sidebar 2.2, "Cosmic Rays and Cosmic Accelerators".
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From page 15... ...
The existence of high-energy cosmic rays raises the question of how they originated and were accelerated. There are a variety of acceleration mechanisms, ranging from shock waves produced by exploding stars or by gamma-ray bursts to supermassive black holes with strong magnetic fields.
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From page 16... ...
When Vera Rubin and others measured the orbital velocities of stars and clouds of gas, they found a very different pattern: Beyond the centers of spiral galaxies, the orbital velocities of stars and gas clouds do not change. Unlike the solar system, where 99.9 percent of the mass is concentrated at the center, the mass of a galaxy is FIGURE 2.3.1 Just as a wanderer in the desert can experience mirages when light from remote objects is bent by the warm air hovering just above the sand, so also we may see mirages in the universe.
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From page 17... ...
bends the light from more distant faint blue galaxies, creating multiple images of some galaxies and distorting the shapes of others. The use of gravitational leasing allows astronomers to map the dark matter in clusters of galaxies and to directly reveal the enormous amount of dark matter.
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From page 18... ...
The prediction of matter instability is bolstered by evidence that the strengths of the strong and electroweak forces approach a common value at very high energies, an indication of the unification of the forces that sets a possible energy scale for the undiscovered forces responsible for proton decay. Some theoretical predictions of the lifetime of the proton are within the reach of a new generation of experiments; the absence of observed decays will also constrain theory.
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From page 19... ...
For instance, rare nuclear-decay experiments (such as double beta decay) have the potential to probe the absolute scale of neutrino mass down to the minimum mass indicated by the Super-K and SNO experiments, but only if the neutrino meets certain other conditions (that is, if it behaves as a Majorana particle)
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From page 20... ...
By exploiting the full electromagnetic spectrum, astronomers have revealed a great variety of objects in the universe, from the microwave glow of the big bang, to infrared radiation from planets, to the gamma rays emitted by supermassive black holes. Neutrinos of vastly different energies should also be produced by objects in the universe, from relic neutrinos left over from the big bang to those produced by the interaction of the most energetic cosmic rays with the cosmic microwave background radiation.
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From page 21... ...
While detecting very high energy cosmic neutrinos requires the largest-volume detectors yet proposed by scientists, a host of additional frontier experiments require laboratory space of a different nature. Double beta decay experiments, solar-neutrino projects, detectors to observe accelerator-produced neutrinos at great distances, experiments to detect the dark matter that holds together our own galaxy, and searches for proton decay all require laboratory space that is well shielded from the cosmic rays that bombard Earth.
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