Post on 18-Jan-2016
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
KM3NeT: optimization studies for a cubic kilometer neutrino detector
R. Coniglione P. SapienzaIstituto Nazionale di Fisica Nucleare- Laboratori Nazionali del Sud
K. Fratini Istituto Nazionale di Fisica Nucleare- Genova
for the KM3NeT collaboration
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Optimization studies
In order to give a “reference” for the sensitivity, the effective neutrino areas and the detector resolution in the Conceptual Design Report of the KM3Net collaboration a “reference detector” is reported even if it is not the final detector configuration
An optimization work is going on in order to find the best detector geometry which is a compromise between performance, technical feasibility and cost
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
The MonteCarlo simulations
Simulation codes used ANTARES codes modified for km3 detectors + LNS improvements
and generation- water absorption and scattering- optical background isotropic distributed around the event time window- event trigger based on local coincidences
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.
Optimization of the basic elements of the detector geometry:
the detection unit (tower vs string) the photo-sensor unit (PMT quantum efficiency and
directionality)
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Detection units optimizationthree dimensional vs monodimensional
Some examples of operative “Detection Units”
The mono-dimensional
H = 360 m
Antares Icecube
Storey 1
Storey 2
Storey 3
Storey 60
17 m
H = 1000 m H = 70 m
Baikal NT 200
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Detection units optimizationthree dimensional vs monodimensional
Some examples of operative “Detection Units”
The three-dimensional
40m
20m
NestorNEMO
H = 600 m H = 330 m
Storey 12
Storey 1
Storey 2
Storey 3
30m
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Detection units optimizationthree-dimensional vs mono-dimensional
20m 1 mfrom to …..
Simulated detection unit characteristics:- instrumented 680 m- number of bars 18- number of PMTs per bar 4 (down-horizontal looking)- bar vertical distance 40 m- PMT 10’’ with QE max 23%81 towers 140m distant
SIMULATIONS AS A FUNCTION OF THE BAR LENGTHBar 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
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Bar length effect
Muon effective areamedian rec
bar length 20m bar length 15mbar length 10mbar length 7.5mbar length 1m
No quality cut applied
Worsening of the angular resolution with shorter bar length
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Bar length effect
quality cut applied
Effective area ratio with respect to 20m
Muon effective area
bar length 15mbar length 10mbar length 7.5mbar length 1m
bar length 20m bar length 15mbar length 10mbar length 7.5mbar length 1m
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Bar length effect
1m bar length
15m bar length
E 102 104 GeV
RMS ~55°
RMS ~65°
rec
rec rec
rec
Vertical muons ->cos >0.8 (~36°)
RMS ~24°
RMS ~27°
cou
nts
cou
nts
cou
nts
cou
nts
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Bar length effect
E 102 104 GeVVertical muons -> cos >0.8 (~36°)
Muon hits in only one tower
15m bar length 1m bar length
recrec
cou
nts
cou
nts
In mono-dimensional detection units the phi angle for vertical muons is not well determined
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
The simulated geometries
Reference detector
169 towers
Number of detection units 225 169
Detection units distance (m) 95 140
PMT type & QE3”
max 33%
10” max 23%
Number of OM 8325 12168
Number of PMT 174825 12168Storey distance (m) 16.5 40
PMT total catode
area (m2)682 535
Volume (km3) 1.05 1.92
Reference detector OM -> 21 PMTs 3”
PMT Quantum efficiency
169 towers OM ->1 PMT 10”
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Quantum efficiency effect
From Hamamatsu catalog PMT < 3”
45%
35%
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Quantum efficiency effectpreliminary results
169 towers QE max 23% 169 towers QE max 45% 169 towers QE max 35% ▬ ref det with QE 33%
max 45% /max 23% max 35% /max 23%
Ratio for 169 towers detector
Neutrino effective areas
Quality cuts applied (~0.1°@30TeV)
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Direction sensitive OM
R
x
R
x
Standard PMT
Direction sensitive OM
mirror
Photocatode
In order to get information on the
Cherenkov light direction -> Light guide
and multi-anodic PMT
Prototype already realized
No information on the arrival direction of
Cherenkov light
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Direction sensitive OM
81 towers 140 m distant detector PMT with standard QE (max 23%)
RatioNeutrino effective areas
< 2°
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Direction sensitive OMpreliminary results
169 towers 140 m distant detectorNo quality cuts applied
RatioNeutrino effective areas
Direction sensitive OMPMT standard
log10E(GeV)
Aeff (m
2)
log10E(GeV)
Rati
o A
eff
R. Coniglione, VLVnT08, Toulon 22.24 April ‘08
Summary
Three-dimensional detection units shows a better reconstruction in particular at low energy E<10÷100 TeV
PMT quantum efficiency and direction sensitive OM improve the effective area at low energy E<10÷100 TeV