NEUTRINOS "''' the most tiny quantity of reality ever imagined by a human being"' F'Reines

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NEUTRINOS"... the most tiny quantity of reality
ever imagined by a human being".

F.Reines

• GÜL ESRA BÜLBÜL

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CONTENT

• 1- Introduction
• 2- History of Neutrinos
• 3- The Sources of Neutrinos
• 3.1- The Solar Neutrinos
• 3.2- Neutrinos from mankind activity
• 3.3-Neutrinos from the earth
• 3.4-Neutrinos from cosmic rays
• 3.5-Neutrinos from the Big-Bang
• 4- Some Orders of Magnitude

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• 5- Features of Neutrinos
• 5.1- The magnetic Spin of Neutrino
• 5.2- Measurement of neutrino mass
• 5.3- The oscillating neutrino
• 6- Solar Neutrino Problem
• 7- Neutrino Detection Experiments
• 8- Conclusion

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1- Introduction

• Neutrinos are similar to the more familiar
  electron.
• Neutrinos are affected only by a "weak"
  sub-atomic force of much shorter range than
  electromagnetism

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2- HISTORY OF NEUTRINOS

• 1930 Wolfgang Pauli hypothesizes the existence of
  neutrinos to account for the beta decay energy
  conservation crisis.
• 1932 Chadwick discovers the neutron.
• 1933 Enrico Fermi writes down the correct theory
  for beta decay, incorporating the neutrino.
• 1946 Shoichi Sakata and Takesi Inoue propose the
  pi-mu scheme with a neutrino to accompany muon.
• 1956 Fred Reines and Clyde Cowan discover
  (electron anti-) neutrinos using a nuclear
  reactor.

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• 1962 Ziro Maki, Masami Nakagawa and Sakata
  introduce neutrino flavor mixing and flavor
  oscillations.
• 1962 Muon neutrinos are discovered by Leon
  Lederman, Mel Schwartz, Jack Steinberger and
  colleagues at Brookhaven National Laboratories
• 1964 John Bahcall and Ray Davis propose
  feasibility of measuring neutrinos from the sun.
• 1965 The first natural neutrinos are observed by
  Reines and colleagues in a gold mine in South
  Africa, and by Goku Menon and colleagues in Kolar
  Gold
• 1968 Ray Davis and colleagues get first
  radiochemical solar neutrino results using
  cleaning fluid in the Homestake Mine in North
  Dakota

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• 1980s The IMB, the first massive underground
  nucleon decay search instrument and neutrino
  detector is built in a 2000' deep Morton Salt
  mine near Cleveland, Ohio. The Kamioka experiment
  is built in a zinc mine in Japan.
• 1985 The "atmospheric neutrino anomaly" is
  observed by IMB and Kamiokande.
• 1986 Kamiokande group makes first directional
  counting observation of solar neutrinos and
  confirms deficit.

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• 1987 The Kamiokande and IMB experiments detect
  burst of neutrinos from Supernova 1987A,
  heralding the birth of neutrino astronomy
• 1988 Lederman, Schwartz and Steinberger awarded
  the Nobel Prize for the discovery of the muon
  neutrino.
• 1989 The LEP accelerator experiments in
  Switzerland and the SLC at SLAC determine that
  there are only 3 light neutrino species
  (electron, muon and tau).
• 1995 Frederick Reines and Martin Perl get the
  Nobel Prize for discovery of electron neutrinos
  and tau lepton

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• 1998 After analyzing more than 500 days of data,
  the Super-Kamiokande team reports finding
  oscillations and, thus, mass in muon neutrinos
• 2001 and 2002 SNO announces observation of
  neutral currents from solar neutrinos
• 2002 Masatoshi Koshiba and Raymond Davis win
  Nobel Prize for measuring solar neutrinos (as
  well as supernova neutrinos).

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• 2002 KamLAND begins operations in January and in
  November announces detection of a deficit of
  electron anti-neutrinos
• 2004 SuperKamiokande and KamLAND present evidence
  for neutrino disappearance and reappearance,
  eliminating non-oscillations models.

Figure 1 Fred Reines and Clyde Cowan at the
Control Center of the Hanford Experiment (1953)
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3-THE SOURCES OF NEUTRINOS The neutrinos in the
universe come from weak interactions (like beta
decays in atomic nuclei. There are many types of
neutrinos origins, which can be quite arbitrarily
classified in five sources 3.1-SOLAR
NEUTRINOS They come along with the process of
thermonuclear fusion inside the stars.
Their energy is quite weak (some MeV) and they
can travel in a long and quite way. They come
from different nuclear reactions whose main
reaction is
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3.2-NEUTRINOS FROM MANKIND ACTIVITYThese
are high energy neutrinos produced by the
particles accelerators and low energy neutrinos
coming out of nuclear reactors. The first ones
are produced to study the structure of the
nucleons and to study the weak interaction. The
second ones are an abundant product made by the
nuclear reactions inside the reactors
cores. 3.3-NEUTRINOS FROM THE EARTH Our great
old planet has kept since its birth many
radioactive atomic nuclei. This is what we call
"natural radioactivity". This radioactivity is
quite important. The power coming from this
natural radioactivity is estimated at about
20.000 Giga Watts
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3.4-NEUTRINOS FROM COSMIC RAYS When a cosmic
ray penetrates the atmosphere, it interacts with
an atomic nucleus and this generates a particles
shower. 3.5-NEUTRINOS FROM BIG BANG THEORY The
"standard" model of the Big-Bang predicts, like
for the photons, a cosmic background of
neutrinos. Those neutrinos, nobody has never seen
them. 4-SOME ORDERS OF MAGNITUDE Our sun emits
around 2x1038 neutrinos per second !... and the
earth receives more than 40 billions neutrinos
per second and cm2.
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• Big-Bang about 330 neutrinos per cm3
  Explosions of supernovae about 0.0002
  neutrinos per cm3
• 5-FEATURES OF NEUTRINOS
• 5.1-MAGNETIC SPIN OF NEUTRINOS
• The measurements of the neutrino magnetic spin
  have been made essentially at nuclear plants by
  observing the diffusion of neutrinos on electrons
  orbiting into atoms.

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• 5.2-MEASUREMENT NEUTRINO MASS
• The mass of electron neutrino is measured since
  almost 50 years using mainly the beta decay. The
  most precise measurements are made using the beta
  decay of tritium. From those measurements, we
  know today that the neutrino mass is less than
  5.1 eV.
• The mass of the muon neutrino can be obtained
  through the study of pion decay into muon.
• The mass of the tau neutrino is obtained through
  the study of tau decay or thanks to high energy
  experiments

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5.3-NEUTRINO OSCILLATIONS In five distinct
measurements, Super-Kamiokande finds neutrinos
apparently "disappearing". Since it is unlikely
that momentum and energy are actually vanishing
from the universe, a more plausible explanation
is that the types of neutrinos we can detect are
changing into types we cannot detect.  This
phenomenon is known as neutrino oscillation.
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6-SOLAR NEUTRINO PROBLEM Since 1975, and
especially since 1995, physicists know with
assurance that the neutrinos coming from our sun
are largely less than predicted. The theory,
which elsewhere describes with an accurate
precision how the sun lives, predicts about 64
billions of neutrinos per second and cm2,
received on earth. Detectors like GALLEX or SAGE
observe not more than 40 billions of neutrinos
per second and cm2. Where are the missing
neutrinos?... Either the model describing the
sun is either something makes the neutrinos
impossible to arrive on the earth of impossible
to detect. If the neutrinos have a mass, then
they could oscillate and those oscillations could
explain the missing solar neutrinos.
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• 7-NEUTRINO DETECTION EXPERIMENTS
• There are essentially three types of detectors,
  according to the energy or origin of the neutrino
  we want to detect i- Detectors for solar
  neutrinos
• ii- Detectors near nuclear plants
• iii-Detectors with neutrino beam
• Two important sites for past and present
  neutrinos studies
• CERN
• Fermilab
• Underground detectors
• Fermilab
• SNO (Sudbury Neutrino Observatory)
• FREJUS (proton decay search)
• Gran Sasso or Gran Sasso (INFN)

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SuperKamiokande 1-2-3 (huge water Cerenkov
detector, Japan) Homestake (Cl37 neutrinos
solaires) SAGE (Soviet American Gallium
Experiment, montagnes Baksan) SOUDAN-2 (Old iron
mine, Minnesota, USA) Nuclear plant
detectors CHOOZ or CHOOZ 2 (Ardennes, France)
San Onofre MUNU at Bugey reactor Undersea
detectors NESTOR BAIKAL DUMAND (Deep Undersea
Muon And Neutrino Detector) International
Neutrino Astrophysical Observatory (New km3 group
BAND Baikal, Amanda, Nestor, Dumand) Detectors
in ice AMANDA (Antarctic Muon and Neutrino
Detector) RAND (Radio Array Neutrino Detector)
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CONCLUSION

• Even a small mass for ubiquitous, nearly
  undetectable neutrinos would make them
  accountable for a substantial fraction of the
  total mass of our Universe, influencing and
  perhaps determining its ultimate fate! A
  measurable mass for neutrinos would also make
  them candidates for the mysterious dark matter.