FDWAVE : USING THE FD TELESCOPES TO DETECT THE MICRO WAVE RADIATION PRODUCED BY ATMOSPHERIC SHOWERS...

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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