probing the hires aperture near 10 20 ev with a distant laser
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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
35 km
HiRes 1
HiRes 2
Terra (Laser)
Laser Parameters
Wavelength 355nm
Energy 2-6mJ (adjustable)
Distance 34km to HiRes 222km to HiRes 1
Direction Fixed - Vertical
Polarization Random
Terra Site – Vertical Laser
laser
Laser Beam – polarization measurements
LA
SE
RP
robe
Depolarizer
Analyzer
Linear Polarization
Random Polarization
Vertical Laser Shot Fired from Terra as recorded by HiRes2
34 km distant
Laser Energy ~3.5mJ
19km
10km
HiRes 1
HiRes 2
Terra (Laser)
Shower~30 EeV
How does the laser compare to a shower?
HiRes 2 HiRes 1
Air Shower
30 EeV Shower
Laser Shower Equivalent4mJ 6x1019 eV
6mJ ~1020 eV
Mean 0.033
Mean 0.04
T = e-VOD
T = e-VOD/sinӨ
Ө
VAOD - Vertical Optical Depth of Aerosol Component
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.
Extra Slides
Compare vertical aerosol optical depth
Terra Laser + HiRes2 detectorHiRes2 Steerable Laser + HiRes1 detector
Atmospheric Monitoring
What is Vertical Optical Depth?
T = e-VOD
T = e-VOD/sinӨ
Ө
VAOD - Vertical Optical Depth of Aerosol Component
Ө2Ө1
LASER DETECTOR
TA2 TM2TA1 TM1
NL NOBS
SA + SM
Measurement of VAOD
2A2MAM1A1MLOBS TT)S(STTNγNγ
2MM1MLMOL TSTNγNγ
MOL
OBS
21 N
Nln
sinθ1sinθ1
1VAOD
)sin/( VAODA eT
MA SS Then for
Atmospheric Measurements from Inclined Laser Shots
45º
60º
DetectorLaser
12.6 km
Linearity
Scaled by10% !!!
45º
60º
DetectorLaser
12.6 km
Clouds