1. 大気モニタR&D Atmospheric Monitoring for TA
テレスコープアレイ計画63
大気モニタR&D Atmospheric Monitoring for TA
M Chikawa, J Kaku，
T Benno, T Nishikaze Kinki Univ. N Hayashida ICRR
　　　　　　　　　　　　　　and TA group
30th March 2004 : 福岡

2. Air Fluorescence
I0∝E I

3. Atmospheric structure
change its transmittance in spatial and vary with time
→ important to know its structure and time variation
→ back scatt., side scatt., sunphoto meter etc. z
atmosphere
scattering process
Rayleigh(molecule)
depends on ρ(z)
Mie(aerosol)
depends on aerosol
wide and local area
time
density ρ(z)
cloud
aerosol
dust,
vapour,
mist, fog
wind

4. Estimate of Mie effect near ground surface (simulation by Ogio(TIT))
EAS
Fluorescence light
generated events = 100, arrival zenith angle : uniform
energy =10^20 eV (fixed)
3km TA
without any cut for the data
cut data w/i 3km
above ground

5. 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.
- cloud monitoring : fiducial volume
 IR(infra red) camera
Observe all sky region
→ IR camera + convex mirror
We, Japanese Atmospheric Monitoring WG,
has a plan to propose for TA atmospheric R&D
based on present R&D and future feasibility study/exp’t at AKENO observatory.
- 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.

6. back scattering (LIDAR method) 　　　　　　　& side scattering (phase function method)
θ=180
0<θ<180 θ
Laser

8. Horizontal Measurement

9. Assumption for analysis
To evaluate the extinction coeff. from Lidar data,
Simple & convenient assumption for structure of atmosphere is applied.
1, only Rayleigh Scattering>10km
Assume this behaviour,
develop a new Lidar system
Inclined Laser shots
2, Atmosphere
Almost Uniform
In Horizontal direction
Lidar
3, Measure Horizontal: Rayleigh+Mie

10. Typical examples

11. 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
Extinction length are calculated by the method of Klett’s model

12. Extinction length vs. height from ground surface
horizontal

13. 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 ±
hazy ± ±
cloudy ±
⇒ should be measured far distance ～20km
solution : install larger mirror, higher power laser

14. parameters of the lidar system
1/2
parameters of the lidar system
required specification for 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
Off-line analysis :
analyze Lidar data from each station independently
< system study based on Akeno R&D >
this performance is achieved by next sysytem

15. New LIDAR system

16. R = T1/T0 = 0.17±1% 透過率測定 Energy meter telescope Energy meter
補正板＋主鏡＋副鏡
R = T1/T0 = 0.17±1%
Nd:YAG Laser
5 mJ / pulse

17. IR Camera Sensitivity : 8 -14μm -20 ゜ ～ 300 ゜ FOV：25.8゜（H）×19.5゜（V）
Cloud monitoring
Sensitivity : 8 -14μm
-20 ゜ ～ 300 ゜
FOV：25.8゜（H）×19.5゜（V）
320×236 pixel
digital value  temperapure

18. IR Camera Cloud monitoring
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
IR camera on AKENO lidar system

19. calculates of edge of the cloud
differential coeff.
threshold cut
digitize: B&W

20. Astro dome
settle an astrodome nearby the telescope station on the ground
install a new LIDAR system inside astrodome

21. 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