EAS Reconstruction with Cerenkov Photons Shower Simulation Reconstruction Algorithm Toy MC Study Two Detector Configuration Summary M.Z. Wang and C.C. Hsu National Taiwan Univ. Dept. of Physics Jan. 9, 2003 Palermo Workshop

CORSIKA-> Reconstruction Air Shower Č photons CORSIKA telesim Reconstruction Input card E, shower axis Read out Č photons and simple detector simulation photon weighting, detectors sampling

Event 0819 Primary particle: electron Incident angle: θ=0 Primary Energy : eV φ : random Č photon wavelength : 290 ~390 nm Fix air density and n Incident distance: 40 km

Detector Configuration. 20 m 4 m 2m 40 X 50 detectors in a 4.5 x 5.0 km 2 area

Detector Parameters Focal length : 43 cm Pixel angular Span: 0.5 degree PMT QE : 0.3 Spot size : 0.04 cm < pixel size cm 40x40 pixels in a 15x15 cm 2 area Lens area : 2m x 2m Transmittance 0.95

Č Photon Image X Y detector area : 10 km x 10km detector simulation area 4.5km x 5.0 km

Photon Density on the Ground eV eV eV Peak position 680 – 750 m

Č Production Height Higher Energy Closer to the Ground Km eV eV10 16 eV

Reconstruction Illustration MINUIT: minimize χ2 to get x,y,θ,φ and E (x2, y2 ) N2. t2   N1, t1 (x1, y1) E, (x, y,θ,φ)

Shower Height eV

Č Photon density Photon density Double Gaussian cone + exponential decay

Fit t0 5 km Fit t0 5 km Similar PDF parameters

Reconstruction CORSIKA data eV ΔxΔx ΔtΔt ΔθΔθ Er/Et

Reconstruction by Toy MC eV Δθ Er/Et

Reconstruction CORSIKA data eV Er/Et Δθ

Reconstruction CORSIKA data eV Poorer results due to PDF and much bigger photon weights? Er/Et Δθ

` d1d1 d2d2 d 1 d 2 Correlation

d1d1 χ2χ2 Rejection of Bad Reconstruction

Er/Et ΔθΔθ Correlation between Er/Et and Δ θ

Study of Two Detector Performance with Toy MC eV electron shower One p.e. threshold, no background Shower starts 30 km away Mirror area 1 m 2 Field of view 12 o Pixel angular span 1 o Vary the distance with 100 m step

Sum of N p.e. 5km is the best?

Efficiency Within 2km, efficiency is flat. →

Reconstructed Angular Deviation 1 o can be achieved

Angular Resolution 2 o for 2 km separation

The Mean Reconstructed Energy Ratio OK, near 1

RMS of Reconstructed Energy Ratio OK, less than 100%

RMS of Reconstructed Position Deviation 1km for 2 o spread

Absolute Time Difference (ns) in Two Detectors 200 ns for separation distance 2km CORSIKA data Hard for coincidence?

We can reconstruct EAS (CORSIKA simulation) with Č photons by two detectors We can reconstruct EAS (CORSIKA simulation) with Č photons by two detectors The reconstruction method is simple and can be improved The reconstruction method is simple and can be improved The study done by a Toy MC indicates the detector separation of 3 o -4 o is optimal The study done by a Toy MC indicates the detector separation of 3 o -4 o is optimal Next Step: Next Step: Need to put in background and utilize pixel information for shower reconstruction Need to put in background and utilize pixel information for shower reconstruction Summary

Background Estimation incident flux: 200 ph/m 2 /srd/ns 0.12m 2 pupil area, 0.5 o pixel size, 4*64 pixels, 20ns gate width, Q.E.=0.2, 2 p.e. threshold, near-by 2-fold coincidence pixel trigger rate=2R1*R2*W R1=5.4/ms pixel trigger rate = 1.2 Hz local trigger rate = 307 Hz Addendum 1/10/03

2km gate width 2μs with time tag 2nd level trigger rate Hz Offline selection based on pattern recognition (neighboring two cells, etc.) can reduce the rate further Expected acceptance for ν τ =10 16 eV is 38% (70% for eV) Addendum 1/10/03

Tasks for Early March Discussion 1/10/03 Optimize detector configuration: number of detectors, number of pixels Compare: efficiency, angular resolution and energy resolution for eV neutrinos Č photon generation: Sigl model + CORSIKA Optics: 0.5m diameter or 1.0m diameter with F~1, Gaussian spot RMS 0.5 o Light collection: 10% (including Q.E.) except light guide simulation if needed Two different readout schemes: single ADC mode and 8 by 8 flag + energy sum mode Background should be added in pixel simulation assuming 200 ph/m 2 /srd/ns.