apostolos tsirigotis simulation studies of km3 architectures km3net collaboration meeting 16-18...
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Apostolos Apostolos TsirigotisTsirigotis
Simulation Studies of km3 ArchitecturesSimulation Studies of km3 Architectures
KM3NeT Collaboration Meeting 16-18 April 2007, Pylos, Greece
The project is co-funded by the European Social Fund & National Resources EPEAEK-II (PYTHAGORAS)
The Underwater Neutrino Telescope software chain
•Generation of atmospheric muons and neutrino events
•Detailed detector simulation (GEANT4)
•Optical noise and PMT response simulation
•Prefit & Filtering Algorithms
•Muon reconstruction
Event Generation – Flux Parameterization
•Neutrino Interaction Events
•Atmospheric Muon Generation (2 Parameterization Models)
μ
•Atmospheric Neutrinos 1 Conventional (no prompt) Model
ν
ν
•Cosmic Neutrinos 5 diffuse flux modelsIt is going to be updated
Earth
Event Generation
Shadowing of neutrinos by Earth Survival probability
Nadir Angle P
rob
abil
ity
of
a ν μ
to
cro
ss E
arth
Neutrino Interaction Probability in the active volume of the detector
Detector Simulation
• Any detector geometry can be described in a very effective way
Use of Geomery Description Markup Language (GDML, version 2.5.0) software package
•All the relevant physics processes are included in the simulation
•All the interactions and transportations of the secondary particles are simulated (Multiple track simulation)
•For the simulation of the neutrino interaction events PYTHIA is used
•Fast simulation techniques and EM shower parameterization
•Optical Noise and PMT response simulation
•Visualization of detector components, particle tracks and hits
Filtering, Prefit and Reconstruction Algorithms
Local (storey) CoincidenceApplicable only when there are more than one PMT looking towards the same hemisphere
Global clustering (causality) filter50% Background rejection while all signal hits survive (1km3 Grid & 1 TeV muon)
Local clustering (causality) filter75% Background rejection while 90% of signal hits survive (1km3 Grid & 1 TeV muon)
Prefit and Filtering based on clustering of candidate track segments
•Χ2 fit without taking into account the charge (number of photons)•Kalman Filter (novel application in this area)
MultiPMT Optical Module (NIKHEF Design)
Outside view Inside View
20 x 3” PMTs (Photonis XP53X2) in each 17” Optical Module
Single PMT Rate (dark current + K40) ~ 4kHz
120 Hz Double coincidence rate per OM (20 ns window)
6 Noise Hits per 6μsec window (9600 MultiPMT OMs in a KM3 Grid)
Optical Module ReadoutOptical Module Readout
•Use a time-over-threshold (TOT) system (multiple thresholds)•Estimation of charge from the time-over-thresholds
+
multiplicity
125 meters
IceCube Geometry: 9600 OMs looking up & down in a hexagonal grid.80 Strings, 60 storeys each. 17m between storeys
Nestor Geometry with 37 Towers in a hexagonal formation.Each tower has 21 floors 120 meters in diameter, with 50 meters between floors.7 Storeys per floor2 MultiPMT OMs per Storey, one looking down the other up10878 Optical Modules
x(m)
y(m)y(m)
x(m)
Nestor Geometry with 19 Towers in a hexagonal formation.Each tower has 21 floors 120 meters in diameter, with 50 meters between floors.13 Storeys per floor2 MultiPMT OMs per Storey, one looking down the other up10374 Optical Modules
200m 300m
Prefit and Filtering Efficiency (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
Events with number of hits (noise+signal) >4
Number of Active OMs
Events passing the prefit criteria
Noise
Signal
Noise
Signal
Number of Active OMs
Signal
Noise
Number of Active OMs
Events passing the prefit criteria after background filtering
Percentage of noise hits after filtering
percentage
Prefit Resolution
Space angle difference (degrees) Zenith angle difference (degrees)
σ = 0.47 degrees
(1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
Fit Resolution (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
Azimuth angle difference (degrees)
σ = 0.07 degrees
σ=0.085 degrees
Zenith angle difference (degrees)
Fit Resolution (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
Space angle difference (degrees)
median 0.1 degrees
σ = 1.05
theta pool (θsim – θrec)/σrecv
Goodness of fit (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
phi pool (φsim – φrec)/σrec
σ = 1.01
Resolution Estimation (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
•Divide the detector in 2 identical sub detectors•Reconstruct the muon separately for each sub detector•Compare the 2 reconstructed track directions
Number of active OMs in one subdetector
Number of active OMs in whole detector
Resolution Estimation (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
Zenith angle difference between the 2 reconstructed directions (degrees)
Space angle difference between the 2 reconstructed directions (degrees)
σ=0.14 degrees
Resolution Estimation (1 TeV Muons, isotropic flux, IceCube Geometry, 9600 OMs)
σ=0.094 degrees σ=0.07 degrees
Zenith angle difference of subdetectors (degrees) Zenith angle difference of whole detector (degrees)
Atmospheric (CC) neutrino events (1-10TeV)Comparison of three different Geometries
Space angle difference between neutrino and muon track
degrees
degrees
median 0.7 degrees
median 0.3 degrees
1 TeV muon neutrino
5 TeV muon neutrino
Atmospheric (CC) neutrino events (1-10TeV)Comparison of three different Geometries
IceCube Geometry (Only Down looking OMs)
IceCube Geometry (Up-Down looking OMs)
Nestor Geometry (Up Down looking OMs)
Muon Energy (GeV)
Rec
on
stru
ctio
n E
ffic
ien
cy
All three geometries have the same resolution (~0.07 degrees in zenith angle)
Atmospheric (CC) neutrino events (100GeV-10TeV)Comparison of 4 different Detectors
IceCube Geometry (Only Down looking OMs)
IceCube Geometry (Up-Down looking OMs)
Nestor Sparse Geometry (Up Down looking OMs)
Nestor Dense Geometry (Up Down looking OMs)
Neutrino Energy (GeV)
Mu
on
eff
ect
ive
are
a (m
2)