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Project Title: High Resolution Fly's Eye
(HiRes)
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Spokesperson:
Pierre V. Sokolsky (University of Utah)
Principal Investigators:
P. Sokolsky & C. Jui (Utah)
-NSF Grants #PHY9974537, #PHY9322298
S. Westerhoff & B. Knapp (Columbia)
-NSF Grant #PHY9904048
R. Clay & B. Dawson (Adelaide)
J. A. J. Matthews (New Mexico)
J. Belz (Montana State)
-NSF Grant #PHY0071069
G. Thomson (Rutgers)
-NSF Grant #PHY0073057
M. Teshima & M. Sasaki (Tokyo).
Program Manager: John N. Matthews (University of Utah)
The High Resolution Fly's Eye (HiRes) is the largest cosmic ray detector, and the only air fluorescence observatory in operation in the world at the start of the 21st Century. We are the world leaders in measuring the energy spectrum, composition, and arrival direction anisotropy of Ultra-High Energy Cosmic Rays (UHECR). Of particular importance in our studies is the continuing search for a cosmic ray flux above the theoretical Greisen-Zatsepin-K'uzmin (GZK) cut-off predicted at ~6x1019 eV, which results from photo-pion production
in collisions with the cosmic background microwave photons.
Accomplishments 1994-2000
Constructed 14-mirror prototype at Little Granite Mountain (HiRes-1) and operated the detector in coincidence with the CASA-MIA ground array between 1994-1997. This effort yielded a definitive study of cosmic rays between 1017 - 1018 eV.
- Ph.D. Thesis by M.J. Kidd (University of Illinois)
- Published: T. Abu-Zayyad et. al. " Evidence for Changing Cosmic Ray Composition between 1017 eV and 1018 eV from Multi-Component Measurements".
Physical Review Letters 84, 4276-4279 (2000).
- In press: "The Prototype High Resolution Fly�s Eye Detector". To be published in Nuclear Instruments and Methods:
- In preparation: results paper on the measured average longitudinal profile for air showers between 1017 - 1018 eV.
- In preparation: results paper on the observed steepening in the energy spectrum near 5x1017 eV.
- In study: observed lateral shower shape of cosmic ray air showers.
Constructed 4-mirror prototype at Camel's Back Ridge (HiRes-2) to study stereo reconstruction techniques
and atmospheric monitoring. Operated between 1994-1997 in coincidence with the HiRes-1 prototype.
- Ph.D. Thesis by C.R. Wilkinson (University of Adelaide)
- Published: T. Abu-Zayyad et. al. "Geometrical Reconstruction with the High Resolution Fly's Eye Prototype Cosmic Ray Detector". Astroparticle Physics, 12, 121-134 (1999).
- Published: L.R. Wiencke et. al. "Radio Controlled Xenon Flashers for Atmospheric Monitoring at the HiRes Cosmic Ray Observatory". Nuclear Instruments and Methods A428, 593-607 (1999).
Reconfiguration of 14 HiRes-1 and 4 Hires-2 prototype mirrors along with 4 newly constructed
mirrors into the new HiRes-1 site in 1997. This detector provides full azimuthal coverage for elevations between 3 and 17 degrees above horizon. More than 3 years of monocular data, approaching twice the exposure of the original Fly's Eye, has been recorded. This constitutes the largest UHE cosmic ray data set ever compiled.
- Preliminary energy spectrum with preliminary evidence for events above the GZK cut-off. Reported at the 26th ICRC (1999), APS Meeting (2000), APS-DPF Meeting (2000)...etc.
- Ph.D. Thesis by T. Abu-Zayyad (University of Utah).
- In preparation: Ph.D. Thesis by X. Zhang (Columbia University).
- In preparation: results paper on the monocular energy spectrum from HiRes-1.
- In preparation: Instrumentation paper for the HiRes-1 detector.
- In study: arrival anisotropy of UHE cosmic rays above 3x1018 eV in the HiRes-1 monocular data.
- In study: search for neutrino-induced air showers in the HiRes-1 monocular data.
Development of new FADC-based electronics, and the construction of the HiRes-2 detector (1995-1999). The HiRes-2 site has been in operation since summer, 1999. Already about 500 hours of stereo data, equivalent
to twice the stereo exposure of the original Fly's Eye, has been recorded. Stereo events have already been used to verify the expected energy resolution of the HiRes-1 monocular analysis.
- In preparation: instrumentation paper on the HiRes-2 FADC system.
- In study: Preliminary energy spectrum for cosmic rays above 1018 eV.
- In study: Search for air showers with sub-luminal propagation speeds as a signature for ultra-heavy strange quark matter.
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