catching rays in the bahamas - stanford...
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Catching Rays in the BahamasAcoustic Detection of Ultra-High Energy Neutrinos
http://hep.stanford.edu/neutrino/SAUND/
Justin VandenbrouckeStanford / Berkeley
RomeOctober 3, 2003
October 3, 2003 Justin Vandenbroucke Rome
Thanks to my SAUND collaborators:Current:
M. Buckingham (Scripps)G. Gratta (Stanford)J. Vandenbroucke (Stanford, now at Berkeley)
Past:S. Adam (Stanford, now at Cornell)T. Berger (Scripps)N. Lehtinen (Stanford, now at Hawaii)Y. Zhao (Stanford)
And to AUTEC and the U. S. Navy:D. BelascoJ. CecilD. DeveauD. KapolkaT. Kelly-Bissonnette
October 3, 2003 Justin Vandenbroucke Rome
Cosmic ray spectrum
October 3, 2003 Justin Vandenbroucke Rome
The Greisen-Zatsepin-Kuzmin (GZK) cutoff
1 event / km2 / century → detector innovation key!
October 3, 2003 Justin Vandenbroucke Rome
Cosmic ray showers
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So what?
A crossroads of exciting physics- active galactic nuclei- gamma ray bursts- grand unified theories- topological defects (magnetic monopoles, cosmic strings, domain walls)- supersymmetry- dark matter- Lorentz invariance violation- extra dimensions- gravity at a TeV
All key to understanding the universe!
October 3, 2003 Justin Vandenbroucke Rome
Charged particles in fluids → sound!
- first discussion of the ideaG. A. Askaryan Sov. J. Atom. Energy 3 (1957) 921
- extensive theoretical analysisJ. G. Learned Phys. Rev. D 19 (1979) 3293
- experimental confirmationL. Sulak et al. NIM 161 (1979) 203
- sensitivity studies towards a neutrino telescopeN. Lehtinen et al. Astroparticle Physics 17 (2002) 279—292
- growing interest in acoustic arraysStanford workshop on acoustic cosmic ray and neutrino detection,September 2003 http://hep.stanford.edu/neutrino/SAUND/workshop
October 3, 2003 Justin Vandenbroucke Rome
Expected neutrino signal
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Ocean as particle detector
N. Lehtinen
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Extreme pancakes
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The Tongue Of The Ocean (TOTO)
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The Atlantic Undersea Test and Evalutation Center (AUTEC)
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AUTEC hydrophones
SAUND (7 km2)
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The SAUND array
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Hydrophones on sea floor
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Site 3
October 3, 2003 Justin Vandenbroucke Rome
Site 3
October 3, 2003 Justin Vandenbroucke Rome
DAQ
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DAQHardware- 1.7 GHz Pentium 4- ADC card- 60 GB external hard drive
Software- digital matched filter- variable threshold- 179 kHz sampling- 60 events/minute target- 1-2 GB / 24 hrs
October 3, 2003 Justin Vandenbroucke Rome
Adaptive threshold
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Calibration sources
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21 events per lightbulb
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Sea surface reflection
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Sea floor reflection
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Direct signal
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Lightbulb positions reconstructed
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Lightbulb positions reconstructed
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Lightbulb depths reconstructed
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Lightbulb energies reconstructed
Bulb Depth (m) P (kPa) E0 (J)1 160 1563 2342 107 1047 1573 139 1360 2044 166 1626 2445 126 1237 1866 101 990 1487 86 838 1268 135 1324 1999 188 1842 276
10 290 2846 427
October 3, 2003 Justin Vandenbroucke Rome
Integrated livetime
- 70% duty cycle- 211 days live- 25 million events- 350 GB
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Five-phone coincidence
Require1) Events obey causality: tij < dij /vsound
2) Geometry consistent with pancake (2D circle) shape:
accepted:
rejected:
October 3, 2003 Justin Vandenbroucke Rome
AUTEC sound velocity profile (SVP)
October 3, 2003 Justin Vandenbroucke Rome
Refraction
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Refraction shadow
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Refracted pancake
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Time difference of arrival (TDOA) localization achieved
October 3, 2003 Justin Vandenbroucke Rome
Localization → energy reconstruction
October 3, 2003 Justin Vandenbroucke Rome
Example of a five-phone event
October 3, 2003 Justin Vandenbroucke Rome
Example of a five-phone event
October 3, 2003 Justin Vandenbroucke Rome
October 3, 2003 Justin Vandenbroucke Rome
Neutrino flux limits
...SAUND limits coming soon
October 3, 2003 Justin Vandenbroucke Rome
Conclusions
What we have learnedRefraction significant > 1 kmcsound = clight / 200,000 !!(Distinguishable) backgrounds exist~1021 eV threshold (1.5 km array spacing)
What is nextEfficiency checksFlux limits
Onward and downward (SAUND-II)On to more phones, collecting area (250 km2), computingDown to the Gaussian floor
October 3, 2003 Justin Vandenbroucke Rome
Thanks to my SAUND collaborators:Current:
M. Buckingham (Scripps)G. Gratta (Stanford)J. Vandenbroucke (Stanford, now at Berkeley)
Past:S. Adam (Stanford, now at Cornell)T. Berger (Scripps)N. Lehtinen (Stanford, now at Hawaii)Y. Zhao (Stanford)
And to AUTEC and the U. S. Navy:D. BelascoJ. CecilD. DeveauD. KapolkaT. Kelly-Bissonnette
More information:http://hep.stanford.edu/neutrino/SAUND