Performance of flexible tower with horizontal extent R. Coniglione and P. Sapienza Istituto Nazionale di Fisica Nucleare- Laboratori Nazionali del Sud R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Optimization studies An optimization work is going on in order to find the best detector lay-out Flexible structures with horizontal extend have been explored: beam length beam like structure vs triangular like structure number of PMT per floor tower distance Compromise between performance, technical feasibility and cost R. Coniglione, KM3NeT, Paris 15.16 October ‘08

The MonteCarlo simulations Simulation codes used ANTARES codes modified for km3 detectors + LNS improvements m and n generation water absorption and scattering included optical background isotropic distributed around the event time window event trigger based on local coincidences reconstruction code based on PDF (Aart Strategy) In order to get the angular resolution of  0.1° at 30 TeV (design goal of the detector) quality cuts on the reconstruction are applied. R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Detection units optimization: the bar length Simulated detection unit characteristics: instrumented height 680 m number of floors 18 number of PMTs per floor 4 (down-horizontal looking) bar vertical distance 40 m PMT 10’’ with QE max 23% bar perpendicular with respect to the near one Cuboid with 81 towers 140m distant (0.8 km3) SIMULATIONS AS A FUNCTION OF THE BAR LENGTH Bar length 20, 15, 10, 7.5, 1 m -> same detector volume same number of PMT photocatode area From a three-dimensional to a mono-dimensional detection unit from to ….. 1 m 20m R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Bar length effect muon effective area Muons with E-1 spectrum up - going 50 kHz optical noise NO quality cuts applied median DW m-mrec bar length 20m  bar length 15m bar length 10m bar length 7.5m bar length 1m Worsening of the angular resolution with shorter bar length R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Bar length effect muon effective area Muons with E-1 spectrum up - going 50 kHz optical noise Quality cuts applied (0.15°@30 TeV) Effective area ratio with respect to 1 m bar length geometry bar length 20m  bar length 15m bar length 10m bar length 7.5m bar length 1m 100 GeV1 TeV  1 TeV10 TeV 10 TeV1 PeV  8÷10 m bar length good compromise between performance, deployment and transportation requirements R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Bar length effect 15m bar length Em 102 104 GeV Vertical muons -> RMS ~24° RMS ~55° counts counts Em 102 104 GeV Vertical muons -> cos qm >0.8 (~36°) q-qrec j- jrec 1m bar length RMS ~27° RMS ~65° counts counts q-qrec j- jrec R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Bar length effect Em 102 104 GeV Vertical muons -> cos qm >0.8 (~36°) Muon hits in only one tower counts 15m bar length 1m bar length counts q-qrec j- jrec  In mono-dimensional detection units the phi angle for vertical muons is not well determined R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Triangular vs beam beam like structures PMT location in the floor N° PMT & Size (inch) N° Tower Tower distance (m) floor distance N° floor/tower N° PMT/floor Volume (km3) Triangle-like 7772 10”(23%QE) 81 140 40 16 3 pairs dh 1.14x1.14x0.60= 0.78 Beam like 3pairs - 2dh 1 dd Triangle - like Simulated dimensions Beam - like Simulated dimensions R (m) 1 2 3 5 7 l (m) 1.7 3.5 5.2 8.5 11.9 l (m) 1 5 7.5 10 15 20 PMT down-horizontal on the triangle vertexes l R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Triangular vs beam beam like structures neutrino effective areas Neutrino with E-2 spectrum up-going 50 kHz optical noise Quality cuts applied 1 -100 TeV Median 0.2° ± 5% beam15m/triangle5m = 1.24 beam15m/triangle3m = 1.41 Aeff (m2) n beam10m/triangle5m = 1.11 beam10m/triangle3m = 1.27 Triangle-like structure plotted vs triangle side  triangle-like beam-like feasibility for a triangle like structure -> max l =5m Beam like structure seems to be favorite R. Coniglione, KM3NeT, Paris 15.16 October ‘08

number of PMT per floor Comparison NEMO - ANEMONE 6 PMT/floor N° PMT & Size (inch) N° Tower Tower distance (m) Bar distance N° floor/tower N° PMT/floor Orientamento Volume (km3) 6pm/floor 7776 10” 81 140 40 16 3pairs - 2dh 1 dd 1.14x1.14x0.60= 0.78 4pm/floor 5184 2pairs dh 6 PMT/floor 4 PMT/floor OR R. Coniglione, KM3NeT, Paris 15.16 October ‘08

PMT/floor neutrino effective area Neutrino with E-2 spectrum up - going 50 kHz optical noise Quality cuts applied 1.5°@30 TeV Effective area ratio 6PMT/4PMT geometries 4 PMT/floor  6 PMT/floor Higher effective area at low energy for 6PMT/floor R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Tower & floor distance muon effective area 81 towers 20 m bar length 18 floor 4PMT/floor tower floor V spacing spacing (km3) Black line 140 m 40 m 0.85 Red square 300 m 60 m 5.8 Black points 300 m 40 m 3.9 Higher local PMT density -> higher effective area at low energy Higher instrumented volume -> higher effective area at high energy R. Coniglione, KM3NeT, Paris 15.16 October ‘08

Outlook Results of a preliminary work to define input parameter ranges for new simulations have been presented (see table shown by J.P. Ernenwein) In the next future….. In a first instance the optimization will be performed maximizing the number of up-going neutrino for a given detector cost. In a final step the optimization will be checked taking into account the atmospheric muon and neutrino backgrounds (see talk by Sapienza). Effective neutrino areas, angular resolution and sensitivity to point like and diffuse flux will be estimated. R. Coniglione, KM3NeT, Paris 15.16 October ‘08

R. Coniglione, KM3NeT, Paris 15.16 October ‘08