Antonis Leisos A sea top infrastructure for calibrating an underwater neutrino telescope the calibration principle using atmospheric showers the calibration principle using atmospheric showers construction and performance of the prototype detector station construction and performance of the prototype detector station Monte Carlo Studies Monte Carlo Studies TeV Particle Astrophysics August 2007 Venice, Italy G. Bourlis, P. Christopoulou, N. A. B. Gizani, A. Leisos, P. Razis, A. G. Tsirigotis and S.E. Tzamarias

1 km 2 km SPASE air shower arrays calibration of AMANDA angular resolution and pointing ! resolution Amanda-B10 ~ 3.5° spase-amanda IceCube IceTop

The General Idea… Angular offset Efficiency Resolution Position Physics ? C.R. composition UHE ν - Horizontal Showers Veto atmospheric background – Study background

~4km ~20km Isotropic on the top of the atmosphere BUT …

Pierre Auger: M. Are et al. Ast.Part. 14: Haverah Park ( 12km 2 effective area and 2π coverage in φ for 10 years operation less than 100 detected showers with reweighting Blind fit Okada model NESTOR: muon 4000m

Floating stations The Concept 3 stations with at 16 m 2 scintillator detectors each Angular offset Efficiency Resolution Position reweighting Blind fit Okada model NESTOR: muon 4000m

HELYCON Station GPS Scintillator-PMT DAQ ~20 m 1 m 2 Single Station Set-Up Triangulation Shower Direction Scintillator-PMT 4·(1W/counter)+30W(PC+electronics)

Simulation Tools CORSIKA (Extensive Air Shower Simulation) GEANT4 (Scintillation, WLS & PMT response) Fast Simulation also available

Simulation Tools DAQSIM (DAQ Simulation) HOUANA (Analysis & Track Reconstruction) Time (ns) Height (mV) Zentih (degrees)

Simulation Tools GEANT4 Muon Propagation to KM3 HOU-KM3 Muon track (s) reconstruction dmdm L-d m (V x,V y,V z ) pseudo-vertex dγdγ d Track Parameters θ : zenith angle φ: azimuth angle (Vx,Vy,Vz): pseudo-vertex coordinates θcθc (x,y,z)

Monte Carlo Studies- Outlook ·10 15 eV E~ ·10 15 eV: 2500 showers/m 2 /year Single station detection: 351m 2 effective area (depends on geometry and selection cuts) Multi-Station: separation <100m, better resolution E> eV: 1 shower/m 2 /year TO BE STUDIED 35% of the detected showers include a muon which arrives at the Neutrino Telescope (depth 4000m) with an energy >300GeV General Remark: 3 stations operating for 10 days can identify an angular offset with an accuracy of 0.15 oSpecifically…

Monte Carlo Studies Depends on: Detector separation Selection criteria Shower direction Typical Values 1)No cut: σ= 4.5 ο 2)Total Collected Charge > 10 mips: σ=2.22 ο 3)Total Collected Charge > 25 mips: σ=1.33 ο 4)Total Collected Charge > 30 mips: σ=1.2 ο Atmospheric shower simulation by CORSIKA - muon transportation to the detector DEPTH by GEANT4 - Sea-Top Detector detailed simulation GEANT4_HOU PRELIMINARY Θ rec -Θ true Angular Resolution in Single Shower Reconstruction

Multi Station Set up improve resolution – higher energies GPS Synchronisation Δt < ± 6ns using sawtooth correction

curvature thickness Total collected charge [pe] Time Delay (ns) Time Spread (ns) Multi-Station Operation Monte Carlo Studies in Progress Total collected charge [pe]

The HELYCON Detector Module Scintillator 2 Scintillator 3 GPS timestamp Station Server Scintillator 3

HELYCON ReadOut Electronics GPS Input USB Port Trigger Ouput4 PMT Signal Inputs 25ps accuracy TDC HPTDC 32 channels (LR) – 8 Channels (HR) 25ps (HR) to 800 ps (LR) accuracy Self Calibrating D. Loucas INP DEMOKRITOS

Response to Showers Discriminator (1.5 MIP) Trigger Input A Input B ~10m trigger arrival time ~60 mips ~50 mips 14.2ns 5.4ns θ=31 ο ± 8 ο

Response to Minimum Ionizing Particles Scintillator A Scintillator B Lead DAQ based on TDS5052 Tektronix (5 Gsamples/s) discriminators Inputs Trigger

Response to a MIP DAQ S/W based on LabView On-Line analysis - distributions Charge (in units of mean p.e. charge) At the Detector Center Data - Monte Carlo Prediction Detailed Monte Carlo description PRELIMINARY Digitized Waveforms saved on hard disk

Response to a MIP Detector Uniformity (the worst case) Charge (in units of mean p.e. charge) X Y Typical Mean Numb. of p.e. per m.i.p. : 23 (± 16% variation) PRELIMINARY

Response to a MIP Detector Uniformity - Timing Scintillator A Scintillator B Lead discriminators Inputs Trigger ΔΤ consistent with the difference of optical path (fiber refractive index n=1.6) PRELIMINARY

Timing vs Pulse Hight thickness Input A Input B Discriminator (1.5 MIP) Trigger Slewing Resolution

Response to Showers Trigger Detectors >1 mip Detectors A.and.B > 0.5 mips zenith angle [degrees] Trigger Detectors > 1 mip Detectors A.and.B > 1.5 mips α=9.4±0.2 PRELIMINARY

Lab Measurements (a) Discriminator (1.5 MIP) Input C Trigger A1 A2 A3 B1 B2 B3 θ Α -θ Β μ=-0.1±0.3 σ=7.6 ± 0.2 Pull Deposited Charge per counter > 4 mips 6 Active counters μ=-0.06±0.05 σ=1.02 ± 0.03 MC -Data Data ___ M.C. Prediction

Lab Measurements (b) Discriminator (1.5 MIP) Input C Trigger A1 A2 A3 B1 B2 B3 Deposited Charge per counter > 4 mips 6 Active counters μ=0.1±0.6 σ=4.5 ± 0.5 θ m -θ tr Pull μ=0.01±0.1 σ=0.9 ± 0.1 MC Prediction GROUP A GROUP B μ=0.3±0.8 σ=5.2 ± 0.8 θ m -θ tr Pull μ=0.02±0.1 σ=0.9 ± 0.1 DATA δθ=4.6 DATA δθ=5.6

dt=0 16m 2 Scintillator Station 19m 5m 1 m 2 Scintillation Counter dt 1 dt 2 dt 3

Time corrections

Detection Efficiency Efficiency Events A hit is considered when there is more than 4 mips deposited charge

Muon Propagation μ track km3 Geant Simulation (propagation & Energy Loss) Accepted if muon with E>2TeV goes through km3 Muon Track Reconstruction (A. Tsirigotis talk) Zenith angle < 13 deg

Muon vs Shower Axis

Primary Zenith Angle Resolution Deposited Charge per counter > 4 mips Number of Hits > 10

Primary Azimuth and Space angle Resolution Deposited Charge per counter > 4 mips Number of Hits > 10

Performance Plots

Charge Time (ns) Charge (in units of mean p.e. charge) At the Detector Center Data - Monte Carlo Prediction Scintillator A Scintillator B Lead discriminators Inputs Trigger Data ___ M.C. Prediction

Charge parameterization AGASA parameterization (S. Yoshida et al., J Phys. G: Nucl. Part. Phys. 20,651 (1994) Parameters depend on (θ, Ε, primary) Mean particle density registered by an active counter

Primary Impact determination Absolute Position resolution ~ 0.5 m

Performance Plots

Telescope Resolution Telescope resolution ~ 0.1 deg Surface Area resolution ~ 1 deg Telescopes resolution measurement Impossible Inter calibration σ=0.014 σ=0.094 σ=0.062

Conclusions The operation of 3 stations (16 counters) for 10 days will provide: The determination of a possible offset with an accuracy ~ 0.05 deg The determination of the absolute position with an accuracy ~ 0.6 m Efficiency vs Energy and Zenith angle… Resolution No!