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FDWAVE :USING THE FD TELESCOPES TO
DETECT THE MICROWAVE RADIATION PRODUCED BY ATMOSPHERIC SHOWERS
SimulationC. Di Giulio, for FDWAVE
Chicago, October 2010
Spherical mirror with radius
of curvature of 3.4 m
Camera of pmt placed on a
spherical focal surface with a
FOV ~ 30ox30o
FD Telescope
FD camera
440 PMTs on a spherical surface
(Photonis XP 3062)
Pixel 1.5o
Spot ≈ 1/3 pixel
Mercedes
90
cm
light collectors to recover border inefficiencies
Auger FD: 10560 PMTs
“mercedes star” with aluminized mylar reflecting walls
Spherical mirror with radius
of curvature of 3.4 m
Camera of pmt placed on a
spherical focal surface with a
FOV ~ 30ox30o
Diaphragm with diameter of
2.2 m
FD Telescope
Schmidt optics
C FCircle of minimum
Confusion Diameter 1.5 cm
Spherical aberration
C
F●
Coma suppressed
Diaphragm
CF●
Coma aberration
Spherical focal surface
Spherical mirror with radius
of curvature of 3.4 m
Camera of pmt placed on a
spherical focal surface with a
FOV ~ 30ox30o
Diaphragm with diameter of
2.2 m
Corrector ring to increase the
aperture
+ UV optical filter
FD Telescope
Use LL1 & LL6 to detect microwave radiation equipping the empty pixels with microwave radio receivers
Pixels without photomultipliers (removed to be installed in HEAT - - Photonis stopped the production)
220 pixels available (not considering the columns adjacent to pmts)
FDWAVE
14
3First 32 horn positions
LL6
No pmts
Use the profile reconstructed with pmts to estimate the energy deposit seen by radio receivers
Use the standard FD trigger and readout the radio receivers every FDshower candidate
?
FDWAVE
LL mirrors are produced with aluminium --> good reflectivity
Reflector
Spherical FD
Parabolicmicrowave telescope
spherical aberration
in the focus all rays have the same phase!
BUT: the parabolic dish is not suitable for track imaging purposes because of the strong aberrations for inclined rays the best reflector is spherical !!!
Optics
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Parabolic vs Spherical• Image good only near the
center of the field.
• Only the star in the center of the field is on the optical axis.
• Spherical--> Schmidt camera
• Good image over large field
• Only part of the mirror it’s used to produce the image.
• Every image it’s produce by similar part of the mirror
• Every stars lies on the optical axis of such part
• correcting plates? Unnecessary for radiofrequency
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Bibliography on Spherical Reflector in wave
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FD optics simulation
Diaphragm2.2 m
Camera shadow ≈ 1 m
GRASPwww.ticra.com
waves in only in one plane
Radio receivers in the camera center
at 1.657 m from the mirror~ 7 GHz - HP=600
Auger mirror
R = 3.4 m
GRASP FEED Specifications:
FEED: Fondamental Mode circula waveguide.
Pattern:Gaussian Beam Pattern Definition
Taper angle = 55.8 deg
Taper = -12
Polarsation = linear x
Far forced = off
Factor db=0 deg=0
Spherical
aberration
Spherical
ParabolicGain (G)
with respect
to isotropyemission
Simulation without Diaphragm and Camera shadow
viewing angle
Parabolic it’s better
than spherical
~ 35 dBi
~ 15 dBi
Simulation with Diaphragm Aperture
Parabolic
Spherical
Gain (G) with
respect to
isotropyemission
viewing angle
Simulation with Diaphragm and Camera shadow
Parabolic
Spherical
secondary lobes due mainly to camera shadow
~ 10 dBiGain (G)
with respect
to isotropyemission
viewing angle
~ 10 dBi
Optimal Wavelenght
pixel field of view
Half Power Beam Width
optimal
camera body
4.56 cm
inserting antennain camera holes lower limit on
1.50: 5 GHz
> 6.6 GHz
6 cm
antenna
Telescope Aperture
€
Aeff =λ2G
4π
€
Aeff =η πD
2
⎛
⎝ ⎜
⎞
⎠ ⎟2
− 0.85 ⎡
⎣ ⎢
⎤
⎦ ⎥
€
η≈50%
constant within 1%
aperture from Gain
efficiency factor
FEED
Conical Horn in the frequency range [9-11] GHz
support(can be removed)connector for
output signal(can be put in
another position)
waveguide 24.5 mm
(<b)
circular aperture 42 mm
(<a)
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camera holes b=38 mm
maximum aperture a=45.6 mm
Contacts with SATIMO experts to lower the frequency
(0.70-0.80)
Horn positions
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Tempered Glass 3dB Transfert loss.
Filter attenuation: as tempered glass??
€
ΔI = k T
Aeff Δt Δf~ 0,8⋅10−22 W
m2Hz
Expected flux density
P.W.Gorham et al., Phys.Rew. D78, 032007 (2008)
Background
€
100 ns
€
1 GHz
≈ 100 K + penalty factor (100 K?)
1÷2
€
I ≈E[EeV]
0.34
⎛
⎝ ⎜
⎞
⎠ ⎟α
1
R[km]2 3⋅10−22 W
m2Hz
Signal / Background
staying within FD building (diaphragm, …)
bandwidth
quadraticscaling
linearscaling
15 km10 km
Possibility to increase I/Δ Δt > 100 ns
averaging over more showers and FADC traces
Rate in LL6 above 1018.5eV: 50 events/year
Signal / Background
Elettronics & DAQ
amplifier ANTENNApower
detectorFADC
Log-power detector AD8317up to 10 GHz 55 dB dyn. range
typical signals very low I Aeff Δf ≈ -90 dBm (1 pW)
we need 50 dB amplification with low noise to match the power detector dynamic range
AMF-5F-07100840-08-13P
7.1-8.4 GHz Gain 53 dB Tnoise = 58.7 K
use the FD FADCs a trigger signal is needed radio signals will be available in a friendly style
CONCLUSIONS
• The possibility to detect the microwave emission from air shower using the FD telescope optic it’s under investigation.
• To detect different part of the same shower with different techinque (Fluor. and Microwave) it will be nice.
• We need a background measurement in the FD building to estimate the system noise temperature.
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