1. 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

2. 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

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

4. 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

5. Neutrino effective areas
Quality cuts applied
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%

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

7. Median and effective areasdh ud dd
dh dd ud
dh dd ud
qn-m
qn-m
dh/ud dd/ud

8. 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

9. 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

10. 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

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

12. 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

13. Point source sensitivity d=-60°
dh
 ud
 dd a dh dd ud 2
2.2

14. 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 m m
depth [m]
sensitivity
2400
1.95x10-9
3400
1.96x10-9
5000
1.92x10-9 L

15. 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

16. 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 …