trigger issues for km3net the large scale underwater neutrino telescope
DESCRIPTION
Trigger issues for KM3NeT the large scale underwater neutrino telescope. E. Tzamariudaki NCSR Demokritos. the project objectives design aspects from the KM3NeT TDR trigger issues outlook. the project. - PowerPoint PPT PresentationTRANSCRIPT
Trigger issues for KM3NeTthe large scale underwater neutrino telescope
Trigger issues for KM3NeTthe large scale underwater neutrino telescope
• the project
• objectives
• design aspects from the KM3NeT TDR
• trigger issues
• outlook
E. Tzamariudaki
NCSR Demokritos
• The KM3NeT Consortium aims at developing a large deep-sea infrastructure at the Mediterranean sea. A multi-cubic-kilometer Cherenkov telescope for the discovery of sources of high-energy (>100GeV) cosmic neutrinos.
• Long-term measurements in the area of oceanography, marine biological sciences and geophysics
the project
ANTARES, NEMO and NESTOR joined efforts to prepare a km3-size neutrino telescope in the Mediterranean sea
KM3NeT
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high energy neutrino observation: motivation
ν and γ produced in the interaction of high energy nucleons with matter or radiation
0 N X Y Y
cosmic ray acceleration yields neutrinos and gammas with similar abundance and energy spectra
neutrinos:
unique messengers
investigate neutrino “point sources” in the TeV energy regime
KM3NeT objectives
• galactic Supernova Remnants, Microquasars
• extragalactic Active Galactic Nuclei, Gamma Ray Bursts
Field of view includes the Galactic center and complements IceCube
Optical properties of deep sea water: excellent angular resolution
High-energy diffuse neutrino flux
Neutrino cross section is extremely low very large active volume needed
Instrumented volume of several km3 exceed IceCube sensitivity
high energy neutrino observation
• Upward-going neutrinos interact in rock or water
• charged particles (in particular muons) produce Cherenkov light in water at 43° with respect to the neutrino direction
• light is detected by array of photomultipliers
• muon direction is reconstructed using PMT positions and photon arrival times
• the Earth provides screening against all particles except neutrinos
• the atmosphere acts as target for production of secondary neutrinos
KM3NeT: an artistic view
design aspects
Multi-PMT Optical module
31 x 3” PMTs inside a 17” glass sphere
Optical module
1 Digital Optical Module = Dom40 Dom’s on 1 tower = Dom tower
storey
Multi-PMT OM advantages
• separation of single-photon and multi-photon hits
• information on the arrival direction better track reconstruction
• “All-data-to-shore” concept
• Trigger– Multi-PMT optical module:• L1: coincidence of ≥ 2 hits in one optical module (Δt ≤ 10 ns)• Consider coincidences of 2 neighbouring or next-to-neighbouring L1 hits
– Bar provides for easy level 2 filter• Local coincidences of 2 L1 hits on one bar (Δt ≤ 50 ns)• Local coincidences of L1 hits on OMs on neighbouring floors
trigger
trigger studies
anis neutrino generator: no noise and noise-only
anis neutrino generator with noise
atmospheric muon background (MUPAGE) with noise
noise: background from decays and from bioluminescence40 K
ANTARES
trigger: number of hits on an OM
neutrino events (no noise) noise only
number of hits on an OM
hits within 40 ns
hits within 10 ns
noise: 80% of OMs have 2 hits but only 2% are within 10ns
signal: 42% of OMs have 2 hits; > 60% within 10ns (1-10TeV)
number of hits number of hits
First trigger level
5 OMs with hits
5 OMs with L1 hits
trigger level
1 OM hit
1 OM with L1 hit
5 OMs hit
5 OMs with L1 hit
zenith angle
First trigger level
reconstructed events
L1 efficiency
second trigger level
trigger level L1 PMT vicinity cut
well reconstructed events
• apply a requirement on the vicinity of the PMTs hit on an OM:
require 5 OMs with 2 L1 hits on (next-to-)neighbouring PMTs
98% of well reconstructed events fulfill this requirement
second level trigger
• apply a requirement on local coincidences of L1 hits on both OMs of the bar
require 1, 2, 3 such local coincidences
trigger level
L1
1, 2, 3 such local coincidences
Δt < 50 ns
N_coincidences same floor / N_OMs with L1-hit signal events: 30%
noise: 0.8%
trigger
trigger level
L2 requirements: • vicinity of the PMTs hit on an OM and• 2 local coincidences of L1 hits on both OMs of the bar
reco level
2, 3 local coincidences on bar OMs
trigger: atmospheric muons
Nevents @ L1
L2 requirements:
Nevents reconstructed
• vicinity of the PMTs hit on an OM and
• 2 local coincidences of L1 hits on both OMs of the bar
Nevents @ L2
Nevents reconstructed fulfilling L2
N e
ven
ts
muon zenith angle
Nevents @ L2 (3 local coincidences)
trigger
trigger level reco levelL1
L2
L1
L2
ANIS no noise ANIS with noise
• A design for an underwater neutrino telescope at the Mediterranean has been developed and the KM3NeT TDR has been published
• Optimization efforts for the final design definition are converging• A prototype (PPM) is currently under construction
Conclusions and outlook
KM3NET
trigger
• Multi-PMT optical module offers several possibilities - use local coincidences in space and time
• bar can be used for an efficient level 2 filter• noise contribution can be suppressed significantly • work on trigger optimization still ongoing…
Collaboration