Calculation of detector characteristics for KM3NeT storey properties fluxes and rates sources 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Mean photocathode surface (revision) can calculate “mean photocathode surface” for a single storey from properties of PMTs (size, angular acceptance) positioning and number of OMs βtilt θphot α dpmt φ θμ z “ANT” “MULTI” -mean surface for light: response to plane wave -mean surfaces for muons: integration over all light emission directions “NEMO4” 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Mean surfaces for all storey types (without QE) photocathode surface [cm2] mean photocathode surface as function of light direction (plane wave) ANT MULTI NEMO-4 NEMO-6 …and as function of muon direction (theta) light photocathode surface [cm2] ANT MULTI NEMO-4 NEMO-6 gives a measure for the acceptance for up- and downgoing muon events. have to scale with quantum + collection efficiency muon 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Effective detection range Photocathode surface also defines range in which a muon can be detected (absorption, dilution) -> “effective detection range” Rdet(Eμ,θμ) for a muon of energy Eμ, dir. θμ Pdet>50% Rdet -> defines an active “pixel size” around each storey at a certain p.e. threshold (e.g. 2 p.e. for “L1”) Pdet<50%  simple toy Monte-Carlo study: generate “tracks” (straight lines) count number of Rdet spheres hit apply “trigger” criterion (e.g. 5L1) -> “trigger efficiency” -> effective areas (μ and ) 2 p.e. range [m] ex.: ANT storey log10Eμ [TeV] 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

2 p.e. response of the detector to a 10 TeV track “muon” track “touched” (triggered) storeys (at least 2 p.e. with P>50%) Geometry only ! No timing info ! 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Comparison with existing results Comparison with results from existing Monte-Carlo: Tower Design 4-OM points: existing MC curves: this work very good agreement with detailed Monte-Carlo (NEMO group + S. Kuch) Tower Design 6-OM A [m2] data: Coniglione et al, Paris 10/08 A [m2] CUBOID geometry, thesis S. Kuch log10E [TeV] also: qualitative results (influence of string or storey distance, etc) reproduced. Simple tool but works well (at least for guidance / qualitative results) and much faster than full physics Monte-Carlo ! 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Comparison of KM3NeT architectures string and tower architectures, normalised to 1km3 inst. volume String Design (“SD”) Δ lines = 95m Δ storeys = 25m 20 storeys per string 256 strings (1km3) Tower Design (“TD”) Δ towers = 140m Δ storeys = 40m 18 storeys per tower 100 towers (1km3) ANT-type storeys: 15360 OMs 4-OM bars (TD-4): 7200 OMs MULTI-PMT storeys: 5120 OMs ×31 PMTs 6-OM bars (TD-6): 10800 OMs ? ? KM3NeT 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Comparison: neutrino effective areas (2π up-going) normalised to same volume: here SD more sensitive (higher OM density) TD-6 better than TD-4 at low E SD-ant SD-multi TD-4 TD-6 effective area per photocathode area: at high energies, TD-4 best (fewest OMs), worst at low energies SD-ant SD-multi TD-4 TD-6 no reconstruction-> “single-tower” advantage of the TD not included ! 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Expected source rates - examples use the 1km3 designs with expected fluxes for HESS sources (see talk later…) angular resolution 0.1°, energy res. ΔlogE=0.5, 5 years DET S(B)>5TeV nσ P(3 σ) Ecut SD-ant 3.1 (8.2) 1.1 12% 160TeV TD-4 1.9 (4.1) 0.9 13% 126TeV TD-6 2.4 (6.1) 1.0 10% RXJ1713 (SNR) probability for 3 sigma in 5 years optimum energy cut DET S(B)>5TeV nσ P(3 σ) Ecut SD-ant 5.1 (3.3) 2.8 47% 10 TeV TD-4 3.4 (1.7) 2.6 48% 5 TeV TD-6 4.2 (2.5) 2.7 45% 8 TeV Vela-X (PWN) 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Conclusions and Outlook Mean storey surface gives relative sensitivity to up- and downgoing tracks Detection range calculation allows fast estimate of detector properties -> toy model Monte-Carlo Effective areas and systematic effects in good agreement with existing work -> extrapolate to different total volume / PK surface, quantum efficiency, absorption length, PMT size… -> can generate approximate effective areas for event rate calculations Thank you ! 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Backup slides 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

optical modules with ANTARES-type 10” PMT (curved photocathode) Storey types studied ANTARES-type storey: optical modules with ANTARES-type 10” PMT (curved photocathode) 3 optical modules per storey, tilted downward by 45° (or variable) Multi-PMT storey: 31 x 3” PMT distributed in sphere flat angular response single, downward looking OM per storey NEMO-type storey: 10” PMT (as for ANTARES) 4 optical modules per storey: 2 x horizontal, 2 x vertical down 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Average photocathode area for neutrinos and muons weighted by expected quantum efficiencies: ANT/NEMO: 32% MULTI-PMT: 42% mean photocathode area per storey integrated over all muon directions (isotropic flux) up to now, have ignored quantum efficiency ! down up 38% 75% 51% => NEMO surfaces per storey largest… but uses 4 OMs ! 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT

Qualitative results, example: line distance in string architecture detection probability string architecture (100 string grid, 25m storey distances) with ANT storeys String distances: 85m, 100m, 150m, 200m, (50m) 1 .8 50m .6 .4 200m .2 As expected, improvement for larger dS at higher energies; break point slightly below 10 TeV In good agreement with results from NESSY and Sebastian Kuch -1 1 2 3 log10Eμ [TeV] Aeffμ [km2] 200m 5 85m 1 0.5 0.1 0.05 0.01 log10Eμ [TeV] -1 1 2 3 18 / 11 / 2008 Christopher Lindsay Naumann - Geometry studies for KM3NeT