P. Sapienza, R. Coniglione and C. Distefano Point source sensitivity and response to atmospheric muons for different orientation of the PMTs in a tower detector P. Sapienza, R. Coniglione and C. Distefano preliminary results

Outlook Angular acceptance for cosmic neutrino detection Neutrino effective area and angular resolution vs PMT orientation Response to atmospheric muons and rejection Neutrino point source sensitivity To be done list

Mission of the session detector design Ch Mission of the session detector design Ch. Spiering - vlvnt, Amsterdam october 2003

Detector geometry and simulation input number of towers 169 (13x13) tower distance (m) 140 Floor lenght 20 PMT type & QE 10” - 23% number of OM/storey 4 number of PMT 12168 storey distance (m) 40 total PMT catode area (m2) 535 instr. volume (km3) 1.92 ANTARES code modified for km3 detectors neutrino and atm. muon generation water absorption and scattering optical background isotropic distributed around the event time window event trigger based on local coincidences and high charge Reconstruction based on maximum likelihood Detector paramiters NOT optimized! See Rosa talk’s

Neutrino effective areas Quality cuts applied (~0.1°@30TeV) No quality cuts 0° - 30° 30° - 60° 60° - 90° 90° -120° 169 towers QE max 23%  169 towers QE max 35% 169 towers QE max 45% ▬ ref det with QE 33%

High energy neutrino detection dh  ud  dd 100 TeV < E < 100 PeV qn-m Response to high energy neutrinos not sensitive to PMT orientation

Median and effective areas dh ud dd dh dd ud dh dd ud qn-m qn-m dh/ud dd/ud

Angular resolution and effective areas 1 TeV<En<100 TeV dh  ud  dd after quality cuts L qn-m up-down configuration exhibits a lower Aeff especially for horizontal events

Atmospheric muons Sensitivity to neutrino point sources imply rejection of atmospheric muons mis-reconstructed as up-going Detection of the moon shadowing for absolute pointing Evaluation of sensititivity to neutrino diffuse fluxes for several detector depths Code: Mupage v2r2 at 2400, 3400 and 5000 m depth

Atmospheric muon zenith angles q reconstructed atmospheric muons (full line) q atmospheric muons mis-reconstructed as up-going in a 1° bin around a d=-60° source (dashed line (x 700)) qm

Atmospheric muons - Mupage v2r2 orientation ud atm. ric. 5128573 atm. ric. up 155948 atm. ric. up after q. c. on L 2164 dd 4010876 220689 2341 dh 5113969 183761 1047 Energy threshold on muon bundle 3 TeV livetime 44 h (212 days in 1°around d=-60°) depth 3400 m

Signal and background source with d=-60° E-2 dN/dE = 10-9 cm-2 GeV sr-1 x 0.2 Source a = -2 Source a = -2.2 Source a = -1.8 Atmospheric n Number of expected n / year Atmospheric muons (Ebundle >3 TeV) Atmospheric n

Point source sensitivity d=-60° dh  ud  dd a dh dd ud 2 1.96 10-9 1.93 10-9 2.19 10-9 2.2 1.71 10-8 1.69 10-8 1.98 10-8

Atmospheric muons vs detector depth Energy threshold on muon bundle 3 TeV 212 day livetime around a point source with d=-60° and a=-2. lower curves represent atmospheric neutrino fluxes at three depths. 2400 m 3400 m 5000 m depth [m] sensitivity 2400 1.95x10-9 3400 1.96x10-9 5000 1.92x10-9 L

Summary detection efficiency for HE neutrinos DOES NOT depend on PMT orientation up-down configuration SEEMS to be sligtly disfavoured with respect to down-down and down-horizontal configurations for point source search

To do list improve optical background filtering and reconstruction simulations with new Mupage version and improved statistics sensitivity for diffuse flux (at 2400, 3400 and 5000 m depths) sensitivity to Dark Matter Moon shadow detection …