Development of Monte-Carlo tools for the KM3NeT neutrino telescope

Development of
Monte-Carlo tools
for the KM3NeT
neutrino telescope
Claudio Kopper for the KM3NeT Consortium
Erlangen Centre for Astroparticle Physics
VLVνT’09, Athens, Oct. 13 th - 15 th 2009

The KM3NeT Monte Carlo chain
VLVνT’09, Claudio Kopper (ECAP)

The KM3NeT Monte Carlo chain
VLVνT’09, Claudio Kopper (ECAP)

The ANTARES Monte Carlo chain
event generation
• neutrinos (‘genhen’)
• atmospheric muons
• CORSIKA reader
• parametric simulation (‘mupage’)
VLVνT’09, Claudio Kopper (ECAP)

The ANTARES Monte Carlo chain
particle propagation in water
• Geant3-based full simulation
(w/o scattering) ‘geasim’
• fast muon simulation w/ scattering
(lookup tables) ‘km3’
• optical background noise
(white noise)
VLVνT’09, Claudio Kopper (ECAP)

The ANTARES Monte Carlo chain
OM & readout simulation
• included in the previous step
• only ANTARES compatible
(integrated, 2 channels, ‘ARS’ chip)
VLVνT’09, Claudio Kopper (ECAP)

The ANTARES Monte Carlo chain
track reconstruction
• standard ANTARES algorithm
➡ multi-step, log-likelihood based
➡ optimised for ANTARES OMs
(single large PMT per OM)
➡ minor hit selection patches for better
KM3NeT performance
VLVνT’09, Claudio Kopper (ECAP)

The ANTARES Monte Carlo chain
event generation (genhen, ...)
particle propagation (km3, geasim)
OM & readout simulation
track reconstruction (reco)
VLVνT’09, Claudio Kopper (ECAP)

The ANTARES Monte Carlo chain
KM3NeT
event generation (genhen, ...)
particle propagation (km3, geasim)
OM & readout simulation
track reconstruction (reco)
VLVνT’09, Claudio Kopper (ECAP)

Replacement for the ANTARES toolchain
why?
never designed for KM3NeT-sized detectors
hard to maintain
(FORTRAN-based, monolithic,
problematic on 64bit)
alternative toolchain -> crosschecks
....
VLVνT’09, Claudio Kopper (ECAP)

New MC toolchain
replace with a more modular toolchain using the
IceTray software framework
some existing tools:
‘ANIS’ neutrino generator
CORSIKA interface
‘MMC’ lepton propagator
some new tools!
VLVνT’09, Claudio Kopper (ECAP)

New MC toolchain
some new tools!
• particle propagation (Geant4-based)
• light propagation (LUT-based)
• OM simulation
• PMT & readout simulation
• track reconstruction
VLVνT’09, Claudio Kopper (ECAP)

Particle propagation
• two options:
• slow full simulation
• table-based simulation
• space around particle is segmented
• photons are pre-propagated from particle to
segments and stored in tables
• tables can then be used to quickly bring
photons near OMs, remaining sim. is fast then
VLVνT’09, Claudio Kopper (ECAP)

OM simulation
• singlePMT OMs (fully ANTARES-compatible)
• multiPMT OMs
• -> new algorithm including a rudimentary photon
tracking inside the OM
VLVνT’09, Claudio Kopper (ECAP)

Readout simulation
• ANTARES-compatible (ARS chip with two
channels, integrating)
• time-over-threshold (TOT) readout
• incoming p.e.’s are convoluted with pulse shape
• resulting waveform is binned in 1ns bins
• the number of consecutive bins over threshold is
converted into an amplitude (including full walk
correction)
VLVνT’09, Claudio Kopper (ECAP)

New track reconstruction algorithm
(currently work-in-progress)
• fitted the time residual PDF parameterisation used
by IceCube (“Pandel”) to multiPMT pulses in
ANTARES water
• Simple hit filter to remove noise hits
(in-OM coincidences & compatible hits)
• log-likelihood-minimisation (simplex)
• track quality from width of the LLH landscape
minimum (paraboloid fit, idea also taken from
IceCube and implemented for KM3NeT)
VLVνT’09, Claudio Kopper (ECAP)

Some preliminary results
(sample detector, multiPMT OMs)
8
7
angular error distribution for E −2 spectrum, upgoing tracks
(310 strings, 100m string distance, multiPMT OMs, hexangonal surface layout)
no cut [median = 0.71 ◦ ]
cuts for best E −2 sensitivity: σ para < 0.70 ◦ , N PMT ≥ 58 [median = 0.30 ◦ ]
qualiy cut only to reach same resolution: σ para < 0.42 ◦ [median = 0.30 ◦ ]
a.u.
6
5
4
3
2
1
0
−3 −2 −1 0 1 2 3
log 10 (Ψ MC )
VLVνT’09, Claudio Kopper (ECAP)

Some preliminary results
(sample detector, multiPMT OMs)
8
7
6
5
angular error distribution for E −2 spectrum, upgoing tracks
(310 strings, 100m string distance, multiPMT OMs, hexangonal surface layout)
no cut [median = 0.71 ◦ ]
cuts for best E −2 sensitivity: σ para < 0.70 ◦ , N PMT ≥ 58 [median = 0.30 ◦ ]
qualiy cut only to reach same resolution: σ para < 0.42 ◦ [median = 0.30 ◦ ]
σpara:quality parameter
NPMT: crude energy estimator
a.u.
4
3
2
1
0
−3 −2 −1 0 1 2 3
log 10 (Ψ MC )
VLVνT’09, Claudio Kopper (ECAP)

Some preliminary results
(sample detector, multiPMT OMs)
10 3
10 2
Effective area for multiPMT detector, 100 m string distance
(310 strings, trigger: 2T3, zenith range: 90 ◦ − 180 ◦ )
effective area [m 2 ]
10 1
10 0
10 −1
10 −2
10 −3
10 −4
10 2 10 3 10 4 10 5 10 6
neutrino energy [GeV]
VLVνT’09, Claudio Kopper (ECAP)
cuts for best E −2 sensitivity: σ para < 0.95 ◦ , N PMT ≥ 62
cut for same median angular resolution (0.31 ◦ ): σ para < 0.47 ◦

Summary
• new KM3NeT simulation and reconstruction tools
were developed
• full MC chain is working and is being used for
analysis!
VLVνT’09, Claudio Kopper (ECAP)