Neutrinos: Little Neutrons. Not!. Discovery of Radioactivity.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Dear Radioactive Ladies and Gentlemen,
….., how because of the "wrong" statistics of the N and Li6 nuclei and the continuous beta spectrum, I have hit upon a desperate remedy to save the "exchange theorem" of statistics and the law of conservation of energy. Namely, the possibility that there could exist in the nuclei electrically neutral particles, that I wish to call neutrons, ….I agree that my remedy could seem incredible because one should have seen these neutrons much earlier if they really exist.
Reines receives Nobel prize in 1995
(Keep this in mind: it will become important later!)
Solar neutrinosFrom the process of thermonuclear fusion inside a star. Also produced copiously by supernovae. Our sun produces about 2x1038 per second total.
Neutrinos from nuclear reactors and acceleratorsA standard nuclear power plant radiates about 5x 1020 neutrinos per second) and their energy is around 4 MeV.
Neutrinos from natural radioactivity on the earthThe power coming from this natural radioactivity is estimated at about 20,000 Giga Watts (about 20,000 nuclear plants!) and the neutrinos coming from this radioactivity are numerous: about 6 millions per second and per cm2.
Neutrinos from cosmic raysWhen a cosmic ray (proton coming from somewhere in space) penetrates the atmosphere, it interacts with an atomic nucleus and this generates a particles shower. They are called "atmospheric neutrinos".
Neutrinos from the Big-BangThe "standard" model of the Big-Bang predicts, like for the photons, a cosmic background of neutrinos. There are about 330 neutrinos per cm3. But their energy is theoretically so little (about 0.0004 eV), that no experiment, even very huge, has been able to detect them.
Based on the direction, they came from Large Megellenic cloud
Pointing away from sun
Pointing at sun
Credit:R. Svoboda and K. Gordan (LSU) Jun 5, 1998
“[W]e must help you to ensure that America continues to lead the revolution in science and technology. Growth is a prerequisite for opportunity, and scientific research is a basic prerequisite for growth. Just yesterday in Japan, physicists announced a discovery that tiny neutrinos have mass. Now, that may not mean much to most Americans, but it may change our most fundamental theories -- from the nature of the smallest subatomic particles to how the universe itself works, and indeed how it expands.
This discovery was made, in Japan, yes, but it had the support of the investment of the U.S. Department of Energy. This discovery calls into question the decision made in Washington a couple of years ago to disband the Super-conducting Supercollider, and it reaffirms the importance of the work now being done at the Fermi National Acceleration Facility in Illinois.
The larger issue is that these kinds of findings have implications that are not limited to the laboratory. They affect the whole of society -- not only our economy, but our very view of life, our understanding of our relations with others, and our place in time.”
BATAVIA, IL--President Bush met with members of the Fermi National Accelerator Laboratory research team Monday to discuss a mathematical error he recently discovered in the famed laboratory's "Improved Determination Of Tau Lepton Paths From Inclusive Semileptonic B-Meson Decays" report. "I'm somewhat out of my depth here," said Bush, a longtime Fermilab follower……
Above: Bush shows Fermilab scientists where they went wrong in their calculations.
What we know:
What we don’t know:
How do we find out?
120 GeV protons hittarget (1020/Protons per year!)
p+ (“pions”) produced at wide range of angles
Magnetic horns to focus p+
p+ decay to m+n in long evacuated pipe
Left-over hadrons shower in hadron absorber
Rock shield ranges out m+
n beam travels through earthto experiment
But the experiment is hundreds of miles
NUMI: Neutrinos at the Main Injector
MINOS: Main Injector Neutrino Oscillation Search
So the neutrinos start out at Fermilab, and are aimed through the earth at Minnesota. Why Minnesota?
Two Detector NeutrinoOscillation Experiment(Start 2004)
Near Detector: 980 tons
Far Detector: 5400 tons
Decay tunnel before installation of decay pipe
Near detector hall
Solar neutrinosFrom the process of thermonuclear fusion inside the stars (our sun or any other star in the universe).
Some other neutrinos could come from very cataclysmic phemomena like explosions of supernovae or neutron stars coalescences.
Neutrinos from nuclear reactors and acceleratorsThese are high energy neutrinos produced by the particles accelerators and low energy neutrinos coming out of nuclear reactors. The first ones, whose energy can reach about 100 GeV, are produced to study the structure of the nucleons (protons and neutrons composing the atomic nuclei) and to study the weak interaction. The second ones are here although we did not ask for them. They are an abundant product made by the nuclear reactions inside the reactors cores (a standard nuclear plant radiate about 5x 10^20 neutrinos per second) and their energy is around 4 MeV. Neutrinos from natural radioactivity on the earthThe power coming from this natural radioactivity is estimated at about 20.000 Giga Watts (about 20.000 nuclear plants!) and the neutrinos coming from this radioactivity are numerous: about 6 millions per second and per cm2. But those neutrinos, despite of their quantity, are often locally drowned in the oceans of neutrinos coming from the nuclear plants. Neutrinos from cosmic raysWhen a cosmic ray (proton coming from somewhere in space) penetrates the atmosphere, it interacts with an atomic nucleus and this generates a particles shower. They are called "atmospheric neutrinos".
Neutrinos from the Big-BangThe "standard" model of the Big-Bang predicts, like for the photons, a cosmic background of neutrinos. Those neutrinos, nobody has never seen them. They are yet very numerous: about 330 neutrinos per cm3. But their energy is theoretically so little (about 0.0004 eV), that no experiment, even very huge, has been able to detect them. http://wwwlapp.in2p3.fr/neutrinos/ansources.html