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Probing the HiRes Aperture near 10 20 eV with a Distant Laser. C. Cannon , L. Pedersen , R. Riehle , M. Seman, J. Thomas , S. Thomas, L. Wiencke for the HiRes Collaboration. 2003 ICRC HE 1.3.22 Aug. 2 2003 Tsukuba Japan. Experimental Configuration Laser vs. Air Showers. Terra
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Probing the HiRes Aperture near 1020 eV with a Distant Laser C. Cannon, L. Pedersen, R. Riehle, M. Seman, J. Thomas, S. Thomas, L. Wiencke for the HiRes Collaboration 2003 ICRC HE 1.3.22 Aug. 2 2003 Tsukuba Japan
Experimental Configuration Laser vs. Air Showers
Terra (Laser) HiRes 1 HiRes 2 35 km
Laser Parameters Wavelength 355nm Energy 2-6mJ (adjustable) Distance 34km to HiRes 2 22km to HiRes 1 Direction Fixed - Vertical Polarization Random
laser Terra Site – Vertical Laser
Probe LASER Laser Beam – polarization measurements Analyzer Random Polarization Depolarizer Linear Polarization
Vertical Laser Shot Fired from Terra as recorded by HiRes2 34 km distant 19km 10km Laser Energy ~3.5mJ
Shower ~30 EeV Terra (Laser) HiRes 1 HiRes 2 How does the laser compare to a shower?
Air Shower HiRes 2 HiRes 1
LaserShower Equivalent 4mJ 6x1019 eV 6mJ ~1020 eV
Mean 0.033 Mean 0.04 VAOD - Vertical Optical Depth of Aerosol Component T = e-VOD/sinӨ T = e-VOD Ө
Mean 0.033 Mean 0.04 Under good to moderately hazy conditions, laser is always visible. Triggering efficiency for 4mJ shots begins to drop about 0.15 VAOD We consider “good weather” VAOD <0.01
Conclusion Installed a laser to test the reach of our HE aperture. Equivalent light production to a shower of ~6x1019 to 1020 eV Detectors have no trouble seeing this laser under good to worse than acceptable viewing conditions.
Compare vertical aerosol optical depth Terra Laser + HiRes2 detector HiRes2 Steerable Laser + HiRes1 detector
T = e-VOD T = e-VOD/sinӨ Ө What is Vertical Optical Depth? VAOD - Vertical Optical Depth of Aerosol Component
Measurement of VAOD SA + SM TA1 TM1 TA2 TM2 Ө2 NgL NgOBS Ө1 LASER DETECTOR Then for
60º 45º 12.6 km Laser Detector
Linearity Scaled by 10% !!!
60º 45º 12.6 km Laser Detector