EAS Reconstruction with Cerenkov photons

Ching-Cheng Hsu, Jan.29 2003

Ching-Cheng Hsu National Taiwan Univ. Dept of physics Feb. 13 2003

Shower Simulation

Reconstruction Algorithm

Toy MC Study

Summary

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

CORSIKA-> ReconstructionCORSIKA-> Reconstruction

Air Shower

Č photons

CORSIKA

telesim

Read out Č photons and

simple detector simulation photon weighting,

detectors sampling

Reconstruction

E, shower axis

Input card

？

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Detector configurations Detector configurations

4 m

4 m

2m

2m20m

Corsika detector

Our detector

40 X 50 detectors in a 4.5 x 5.0 km2 area

20m

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Detection areaDetection area

Y

X10 km

5 km

4.5 km

10 km

North

West

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Detector Parameters Detector Parameters

Lens area : 4 m2 . Transmittance 0.95

Focal length : 43 cm

Pixel angular Span: 0.5 degree

PMT QE : 0.3

Spot size : 0.04 cm < pixel size 0.375 cm

We have 40x40 pixels of PMT in a 15 cm x15 cm area

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Č Production Height

Higher Energy

Closer to the Ground

31-34 Km

1014 eV1016 eV

1018 eV

Electron showers with new atmospheric model

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Photon density on the groundPhoton density on the ground

1018eV

1016eV

1014eV

Peak position 680 – 750 m

MINUIT: minimize χ2 to get x,y,θ,φ and E

(x2, y2 )N2. t2

N1, t1

(x1, y1)E, (x, y,θ,φ)

Reconstruction Illustration Reconstruction Illustration

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Cerenkov photon Cerenkov photon densitydensity

Double Gaussian

+ exponential decayPh

oto

n d

ensi

ty

Electron shower 1014eV

We know N(E, )

2

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

The AlgorithmThe Algorithm

Within a polar angle 12 region, randomly pick one detector and choose another detector separated by 200 m distances to minimize the following

2 = ( 1 - 0.13)2 / 0.152 + (2 -0.13)2

/ 0.152 + d12 / 302 + d2

2 /302 + [N1-N(E, 1 )]2 / N1 + [N2-N(E, 2 ] 2 / N2 + (l1/c - l2 /c+t2-t1)2/ 0.32

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Reconstruction CORSIKA Reconstruction CORSIKA data data

Δx Δt

Δθ Er / Et

1014eVDetectors distance 200m

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Reconstruction CORSIKA Reconstruction CORSIKA datadata

1016eVDetectors distance 200m

Δx Δt

Δθ Er / Et

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Study of Two Detector Study of Two Detector Performance with Toy MC Performance with Toy MC

1015eV electron shower

One p.e. threshold, no background

Shower starts 30 km height

Mirror area 1 m2

Field of view 12o

Pixel angular span 1o

Vary the distance between the detectors with 100 m step

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Efficiency Efficiency

Within 2km, efficiency is flat.

→

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

OK, near 1

The Mean Reconstructed Energy Ratio

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Reconstructed Augular Reconstructed Augular Deviation Deviation

1o can be achieved

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Summary Summary

We can reconstruct EAS with We can reconstruct EAS with ČČ photons from photons from Corsika data by two detectors.Corsika data by two detectors.

The reconstruction method is simple and can be The reconstruction method is simple and can be improved. improved.

The study done by a Toy MC indicates the The study done by a Toy MC indicates the detector separation of 3detector separation of 3oo-4-4oo is optimal. is optimal.

Next Step: Next Step:

Put in background and use pixel information for Put in background and use pixel information for shower reconstruction. shower reconstruction.

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Reconstruction by Toy Reconstruction by Toy MC MC

1014eV

ΔθEr / Et

Δx Δt

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Absolute Time differenceAbsolute Time difference in in Two DetectorsTwo Detectors

CORSIKA data

200 ns for separation distance 2km

Hard for coincidence?

Ching-Cheng Hsu PSROC 2003, Feb. 12, 2003

Fit to 5 km Fit to 5 km

Similar PDF parameters

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 12, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 13, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 12, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 12, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 12, 2003

Difficulties of Difficulties of Simulation Simulation

Ching-Cheng Hsu PSROC 2003, Feb. 12, 2003

Difficulties of Difficulties of Simulation Simulation