Probing the HiRes Aperture near 10 20 eV with a Distant Laser
-
Upload
lucian-woodward -
Category
Documents
-
view
15 -
download
1
description
Transcript of Probing the HiRes Aperture near 10 20 eV with a Distant Laser
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
Laser Parameters
Wavelength 355nm
Energy 2-6mJ (adjustable)
Distance 34km to HiRes 222km to HiRes 1
Direction Fixed - Vertical
Polarization Random
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
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
Compare vertical aerosol optical depth
Terra Laser + HiRes2 detectorHiRes2 Steerable Laser + HiRes1 detector
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
Conclusion
Installed a laser to probe the reach of our HE aperture (34 km Distant)
Equivalent light production to a shower of ~6x1019 to 1020 eV
Detectors have no trouble seeing this laser under good to acceptable viewing conditions.
Aerosol optical depth measured by Terra Laser/HiRes2 correlates with that measured by HR2SLS and HiRes1 detector