Sebastian Kuch University Erlangen-Nürnberg Update on simulation for KM3NeT using ANTARES software Sebastian Kuch University Erlangen-Nürnberg 24-25 October KM3NeT WP2 Meeting, CPPM

event generation genhen detector simulation km3 Simulation with ANTARES software event generation genhen 109 muon-neutrinos, E-1.4-spectrum from 10 GeV to 107 GeV, up- and downgoing (4p) detector simulation km3 No electronics simulation, hits with TTS and amplitude smearing, 40K-rate of 91 Hz/cm2 of photocathode area (corresponds to 40kHz for 10” PMT) analysis Calculate neutrino effective area for events with more than 10 signal hits (=from muon track), after causality filter, no reconstruction 24-25 October KM3NeT WP2 Meeting, CPPM

Multi-PMT cylinder storey The cylinder storey alternative Photodetection layout Use several small PMs instead of a few large ones ! For example 36 3“ PMs in 3 pressure resistant glass cylinders Same photocathode area as 3 10“ PMs (ANTARES storey) Advantages: Higher Quantum efficiency (~35%) Lower Transit Time Spread (0.5ns) 24-25 October KM3NeT WP2 Meeting, CPPM

Comparison with ANTARES storeys Place ANTARES storeys and cylinder storeys in cuboid grid with distances of 62.5m (4840 storeys, 484 strings, height~600m, 1km3) Run detector simulation and compare effective areas 24-25 October KM3NeT WP2 Meeting, CPPM

Results for cylindrical storey Effective area (events with >10 signal hits selected, no reconstruction) Gain in efficiency, especially at low energies BUT WHY? 24-25 October KM3NeT WP2 Meeting, CPPM

Simulation of cylinder storey with same QE as ANTARES Effective area (events with >10 signal hits selected, no reconstruction) Gain in efficiency mostly because of higher Quantum Efficiency 24-25 October KM3NeT WP2 Meeting, CPPM

Multi-PMT sphere storey cylinder storey probably obsolete New Idea from NIKHEF sphere storey Place 42 3” PMTs in 17” Benthos sphere 1 sphere = 1 storey 24-25 October KM3NeT WP2 Meeting, CPPM

Results for sphere storey Effective area (events with >10 signal hits selected, no reconstruction) Effective area comparable to cylinder storey, better at low energies 24-25 October KM3NeT WP2 Meeting, CPPM

ANTARES storey with 20“ PMs Other direction Use larger PMs Example: Hamamatsu 20” PM (R7250) -Maximum Quantum efficiency ~20% -TTS ~3.5 ns Cuboid detector with ANTARES storeys equipped with 20” PMs Photocathode area times 4 Detector with same overall photocathode area has factor 4 less modules and therefore increased distances and/or no local coincidences. These effects mix and are difficult to discriminate Gain of this concept depends on cost of 20” tube 24-25 October KM3NeT WP2 Meeting, CPPM

Results for storeys with 20” PMs Effective area (events with >10 signal hits selected, no reconstruction) If price of 20” tube is 4 times price of 10” there is nothing to be gained Better below ~100 TeV 24-25 October KM3NeT WP2 Meeting, CPPM

Ring Geometry At E~1TeV muon range in water starts to exceed detector dimension (~1km) Most muons enter from the outside Optimize cross-section area instead of instrumented volume Ring Geometry Example: -312 strings, 4992 (cylinder) storeys -16 storeys/string (dstorey=42m), 1km3 24-25 October KM3NeT WP2 Meeting, CPPM

Results for ring geometry Effective area (events with >10 signal hits selected, no reconstruction) Less strings means less structures, less infrastructure and therefore less cost Less strings, similar performance 24-25 October KM3NeT WP2 Meeting, CPPM

Clusters of densely instrumented strings Cluster Geometry Spacing of storeys energy threshold Clusters of densely instrumented strings Low energy events in clusters High energy events hit several clusters Example: -8 clusters of 12 strings, 1km3 -52 storeys per string (dstorey=12m) -4992 (cylinder) storeys 24-25 October KM3NeT WP2 Meeting, CPPM

Results for cluster geometry Effective area (events with >10 signal hits selected, no reconstruction) Less strings means less structures, less infrastructure and therefore less cost Superior at lowest energies, worse above ~100 GeV 24-25 October KM3NeT WP2 Meeting, CPPM

Influence of string/storey distance storey spacing influences performance at different energies Cluster detector Systematic analysis of these effects Variation of string and/or storey distances for cuboid (with cylinder storeys) Keep number of storeys equal (~cost neutral) Volume will change obviously (All concepts shown so far have 1km3 of instrumented volume) 24-25 October KM3NeT WP2 Meeting, CPPM

Variation of storey distance Effective area ratio (relative to standard cuboid with cylinder storeys) 24-25 October KM3NeT WP2 Meeting, CPPM

Variation of string distance Effective area ratio (relative to standard cuboid with cylinder storeys) Performance above a few TeV can be increased by increasing the instrumented volume, BUT at the cost of low energy efficiency 24-25 October KM3NeT WP2 Meeting, CPPM

Summary Multi-PMT modules with small PMs are a promising alternative, especially at lower energies, mostly due to higher QE Ring geometry shows similar performance as homogeneous cuboid geometry, but requires less strings Cluster geometry allows to increase efficiency below 100 GeV, but at the cost of a ~40% reduction above Increase of string/storey distances increases performance above ~1 TeV (larger volume), but decreases performance below 24-25 October KM3NeT WP2 Meeting, CPPM

Plans for the (near) future Other concepts studied: Detectors with more than 1 km3 of instrumented volume Variations of ring- and cluster-geometry Plans for the (near) future: Get detailed specs for used instruments Optimized selection of events (selection criteria) ToDos: Sensitivities to benchmark fluxes Dedicated KM3NeT reconstruction algorithm Energy reconstruction (Energy resolution!) …. 24-25 October KM3NeT WP2 Meeting, CPPM