1. 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 October ‘08

2. 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 October ‘08

3. 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 October ‘08

4. 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 October ‘08

5. 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 October ‘08

6. Bar length effect muon effective area
Muons with E-1 spectrum up - going
50 kHz optical noise
Quality cuts applied 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 October ‘08

7. 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 October ‘08

8. 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 October ‘08

9. 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 October ‘08

10. Triangular vs beam beam like structures neutrino effective areas
Neutrino with E-2 spectrum up-going
50 kHz optical noise
Quality cuts applied
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 October ‘08

11. 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 October ‘08

12. PMT/floor neutrino effective area
Neutrino with E-2 spectrum up - going
50 kHz optical noise
Quality cuts applied 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 October ‘08

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

14. 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 October ‘08

15. R. Coniglione, KM3NeT, Paris 15.16 October ‘08