Ultra High Energy Cosmic Rays in the North: Measurement of UHE Cosmic Rays with the High Resolution Fly's Eye (HiRes) Detector

Journal Article · Fri Nov 17 04:00:00 EST 2006 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2402615· OSTI ID:20894978

Matthews, J N ^[1]

---

1. University of Utah - Department of Physics, 115 South 1400 East no. 201 JFB, Salt Lake City, UT 84112 (United States)

The High Resolution Fly's Eye (HiRes) observatory has been collecting Ultra High Energy Cosmic Ray (UHECR) data since 1997. The experiment observes cosmic ray air showers via the air fluorescence technique and consists of two observatory sites separated by 12.6 km in the western Utah desert. The two stations can each measure the cosmic rays in monocular mode. In addition, the data from the two stations can also be combined to form a stereo measurement of the air showers. The experiment measures such properties as the energy spectrum, chemical composition, and p-air cross-section of these cosmic rays. It also searches for point sources and other anisotropy. The spectrum is measured above {approx}3 x 1017 eV and shows significant structure including the 'ankle' and a steep fall off which is consistent with the expectation of the GZK. threshold. The spectrum is inconsistent with a continuing spectrum at the 5{sigma} level. The composition is measured using the Xmax technique. It was found to be predominantly light and unchanging over the range from 1018 to 3 x 1019 eV. Finally, several different styles of searches for anisotropy in the data were performed. There are some tantalizing hints including potential correlation with BL Lac objects and the 'AGASA triplet', however these will need to be confirmed with an independent data set.

• OSTI ID: 20894978
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 870; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANISOTROPY
CHEMICAL COMPOSITION
CROSS SECTIONS
EEV RANGE
ENERGY SPECTRA
EXTENSIVE AIR SHOWERS
PEV RANGE
POINT SOURCES
RESOLUTION