大気モニタ r&d atmospheric monitoring for ta
DESCRIPTION
大気モニタ R&D Atmospheric Monitoring for TA. テレスコープアレイ計画 63. M Chikawa, J Kaku , T Benno, T Nishikaze Kinki Univ. N Hayashida ICRR and TA group. 30th March 2004 : JPS @ 福岡. I 0 ∝E. I. Air Fluorescence. Atmospheric structure. - PowerPoint PPT PresentationTRANSCRIPT
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大気モニタ R&DAtmospheric Monitoring
for TAM Chikawa, J Kaku ,T Benno, T Nishikaze Kinki Univ. N Hayashida ICRR and TA group
30th March 2004 : JPS @ 福岡
テレスコープアレイ計画 63
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II00 E∝E∝
II
Air Fluorescence
tcoefficien extinction :1/ length,n attenuatio
:
,,
exp4
0
20
MieRaileighiEASi
EAS
EEII
R
R
AEI
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Atmospheric structurechange its transmittance in spatial and vary with time → important to know its structure and time variation → back scatt., side scatt., sunphoto meter etc.
cloud aerosol dust, vapour, mist, fog
wind
z
density ρ(z)scattering processRayleigh(molecule) depends on ρ(z)
Mie(aerosol) depends on aerosol
wide and local areatime
atmosphere
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Estimate of Mie effect near ground surface (simulation by Ogio(TIT))
without anycut for the data
cut data w/i 3km above ground
3km
EAS
TA
Fluorescence light generated events = 100, arrival zenith angle : uniformenergy =10^20 eV (fixed)
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Atmospheric Monitoring
- lidar system : transparency of atmosphere as far as possible fluorescence light correction factor : I ⇒I0∝EEAS
feasibility study at AKENO suggests aspect to determine extinction coefficient by 20km : steerable Lidar
How to… shoot, DAQ, analyze , and calibrate, etc.
Observe all sky region → IR camera + convex mirror
- cloud monitoring : fiducial volume IR(infra red) camera
- astro dome will be settled on the roof of each three stations in order to install Liar systems
These are the issues that Japanese Atmospheric WG is going to do for TA.
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back scattering (LIDAR method) & side scattering (phase function method)
R
drrT
d
dT
R
AlPP
0
18020
')'(2exp
4)(
θ=180 0<θ<180
Laser
θ
3
8:
)cos1( 2
)( R
R
total
constd
d
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Horizontal Measurement
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Assumption for analysis
1, only Rayleigh Scattering>10km
2, AtmosphereAlmost Uniform
In Horizontal direction
3, Measure Horizontal: Rayleigh+Mie
Inclined Laser shots
Lidar
To evaluate the extinction coeff. from Lidar data, Simple & convenient assumption for structure of atmosphere is applied.
Assume this behaviour,develop a new Lidar system
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Typical examples
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Akeno data 15/Oct/2003
• Lidar exp’t at Akeno• Typical sample of
good results• Corrected intensity of
scattered light PxR2
vs. light path length
0 2 4 6 8
101
102
path length(km)
P×
R2
path length v.s. P× R22003/10/16Observed at Akeno
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Extinction length vs. height from ground surface
constant empirical :
length extinction :
tcoefficienscatter back :
k
kconst
horizontal
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Lidar exp’t
R&D @ Akeno w/ steerable system Mirror diameter 15cm, laser power 5mJ 3-dimension measurement : 10km in vert. & ≦
horiz.
condition α ± Δα fine 0.0639 ± 0.0005 hazy 0.1394 ± 0.0005 0.1645 ± 0.0010 cloudy 0.3254 ± 0.0016
⇒ should be measured far distance ~ 20km solution : install larger mirror, higher power laser
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parameters of the lidar system
to determine extinction coeff. approx. 20km
with few % error
Nd/YAG laser
355nm, 4 mJ
5ns pulse laser
mirror 30cmφ
PMT 3/4”
Gain ~ 106
ADC FADC 12bit
→ spatial resol.: few 10m
1/2
Off-line analysis :analyze Lidar data from each station independently
required specification for Lidar system
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New LIDAR system
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UV透過率測定
0
5
10
15
20
25
30
35
4000
5500
7000
8500
1000
0
1150
0
1300
0
1450
0
1600
0
1750
0
1900
0
2050
0
2200
0
2350
0
2500
0
2650
0
2800
0
2950
0
3100
0
Nd:YAG Laser5 mJ / pulse
Energy meter
telescope
Energy meter
T1=4752±290 T0=128940±798
補正板+主鏡+副鏡R = T1/T0 = 0.17±1%
透過率測定
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FOVFOV :: 25.825.8 ゜(゜( HH )) ×1×19.59.5 ゜(゜( VV ))
320320×236 ×236 pixelpixel
Sensitivity : Sensitivity : 8 8 -14μm-14μm
-20 -20 ゜ ゜ ~ ~ 300 300 ゜゚digital value digital value temperapure temperapure
IR Camera Cloud monitoring
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IR Camera
• IR camera on a steerable system: Akeno Lidar system
• IR camera use 2-dimensional cloud monitor and measure distance by Lidar 3-dimensional cloud monitoring
• option : VTR(visible light) for all-sky waether monitor
Cloud monitoring
IR camera on AKENO lidar system
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calculates of edge of the cloud
differential coeff.
threshold cut
digitize: B&W
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Astro dome
• settle an astrodome nearby the telescope station on the ground
install a new LIDAR system inside astrodome
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Discussion• Range of extinction length : 20km may be OK, but enough? feasibility study at Akeno supports 20km measurement: realistic limit value for our Lidar system during laser shooting to measure might be serious problem for DAQ of E>1018eV, EAS rate from AGASA ★ ext. length α has large dependence of the empirical parameter k (=0.6 to 1.3) in the model
feasibility study to measure absolute light intensity by PMT free from model dependence for Rayleigh scattering
• LIDAR : steerable system need to establish robust system using commercial product
• Astro dome : settle on the ground nearby the TA station • IR camera all sky monitoring and off-line data analysis can be available