Transcript sep04 neutrinos - Charles J Horowitz

P630 Nuclear Astrophysics
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Charles Horowitz
Fall 2002, Indiana University
Course Web site:
http://cecelia.physics.indiana.edu/p6
30/index.html
What is the Universe made of? Why
is it this way?
Note, nucleosynthesis today, discuss
neutrinos later.
Supernova Simulation by Burrows
and Fox
SN Simulation by E. Marietta.
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Exploding Star
is just above
frame and
interacts with
its binary
companion
star
Nuclear Reaction Network
Simulation by B. Meyer
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Burning
of Si
shell to
Ni -> Fe
as SN
shock
passes
through
Vela
Cas A
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Chandra X-ray
Observatory image of
the supernova
remnant Cassiopeia A
shows low, medium
and high energy Xrays (red, green and
blue)
Red is enriched in Fe,
bright greenish white
region in lower left
enriched in silicon and
sulfur.
Abundances
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From meteorites and solar spectra
Meteorites are relatively unchanged
since being formed 4.6 B years ago
with the solar system.
Abundances reflect composition of
primitive solar nebula at time of
formation.
Heavy elements made in previous
generation stars. Not made in Sun.
Most Abundant Nuclei
Nucleus
1H
4He
16O
20Ne
56Fe
14N
28Si
Abundance
0.706
0.275
0.0096
0.0015
0.0012
0.0011
0.0007
Source
Big Bang
Big Bang, CNO, pp
Helium
Carbon
e-process
CNO
Oxygen
Astrophysical Neutrinos
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Dear Radioactive Ladies and Gentleman,
…because of the “wrong” statistics of 14N and 6Li nuclei and the
continuous beta spectrum, I have hit upon a desperate remedy to
save the “exchange theorem” of statistics and the conservation of
energy. Namely the possibility that there exists in nuclei
electrically neutral particles, that I call neutrons, which have spin
½… The mass of the neutrons should be of the same order as the
electron mass and in any event not larger than 0.01 proton
masses. The continuous beta spectrum would then be explained
by the assumption that in beta decay a neutron is emitted in
addition to the electron such that the sum of the energies of the
electron and neutron is constant.
I agree that my remedy should seem incredible because one
should have seen those neutrons very earlier if they really exist.
But only the one who dare can win and the difficult situation…
Thus dear radioactive people, look and judge. Unfortunately, I
cannot appear in Tubingen since I am indispensable here in Zurich
because of a ball on the night of 6/7 December.
Your humble servant, W. Pauli
Dec. 4, 1930
Solar Neutrino Spectrum
Sudbury
Neutrino
Observatory
SNO Under
construction
excavating a
large cavity
Underground neutrino detectors
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Superkamikonda is a giant
tank with 32000 tons of
very clean water.
This is deep in a mine to
protect from cosmic rays.
Very rarely a neutrino will
interact and cause a small
flash of light in the tank.
Phototubes on the walls
detect these flashes of
light.
SK should detect a few
thousand neutrinos from a
galactic supernova.
20 Events from SN1987A
The anti-nu appear to be cooling with time not getting warmer.