pyramid scanning (~1970) luis alvarez (1970): are there undiscovered chambers in the chephren...
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Pyramid Scanning (~1970)
• Luis Alvarez (1970): Are there undiscovered chambers in the Chephren pyramid?
• Investigate with cosmic rays
• Detector installed in chamber at the bottom (B)
• Results compared to what would have been expected from a hidden chamber
• Ultimately, hidden chamber was ruled out
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Volcano Radiography
• Internal structure of volcanoes not very well known
• Use cosmic rays to do radiographical scanning
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Volcano Radiography
• Measure cosmic ray flux through volcano
• Obtain 2D density map
• Lots of data needed
• Then again, geologists have time…
Puy-de-dôme in Clermont-Ferrand, France(ToMuVol project)
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Volcano Radiography
Mt. Iwatodake, Japan (Tanaka et al.)
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National Security
• Safety of cargo an issue
• Nuclear material couldbe smuggled
• Many scanning methods(X-ray, neutrons, etc.)
• But generally expensive,and may introduce radiation
• Alternative: cosmic rays
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Neutrinos
6(has been confirmed)
• Necessary to explain beta decay:
• Postulated 1930 by Wolfgang Pauli
• (Wasn’t too happy about it)
• Assumed to be massless, neutral cousin of the electron
• Almost no interaction with matter
• Still, discovered experimentally (1956 in a nuclear reactor, Cowan-Reines experiment)
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Solar Neutrino Problem
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• The sun is essentially a huge fusion reactor
• Produces large amounts of neutrinos
• Neutrinos can be measured as they arrive on earth
• Wrong amount of neutrinos found!
• Fewer neutrinos arrive than expected from solar models
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Neutrino Oscillation
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• Maybe solar models wrong?
• Turns out, nope.
• Problem resolved when neutrino oscillation was discovered
• Neutrinos switch back and forth between generations as they fly
• Initial experimentsexpected (and saw) onlyelectron neutrinos
• Must have mass to oscillate
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Why Study Neutrinos?
• Good probes for astrophysics:
• Investigate the core of the sun
• Produced in supernovae (in fact, ~99% of a supernova’s energy is radiated in neutrinos)
• Travel very far (and don’t care about the GZK limit)
• Interesting in fundamental particle physics:
• Exact masses? ‘Sterile’ neutrinos? More flavours…?
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Super-Kamiokande
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• Neutrinos interact very little
• Need huge detection volumes
• Super-Kamiokande detector in Japan
• Giant tank of water with photodetectors
• Saw the first measurement of neutrino oscillation
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Super-K Neutrino Event
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Super-K Maintenance
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Large Arrays - ANTARES
2.5 km under Mediterrenean sea (near Toulon) 1 km³ array
at 2.5 km depth 900 detectors
(photomultipliers)
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Large Arrays - IceCube Amundsen-Scott South Pole Station 1.5 - 2.5 km under surface 86 detector strings 5160 sensors
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Any Questions?
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Backup Slides
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