Hunting for Cosmic Neutrinos
in the Deep Sea —
The ANTARES Neutrino-Telescope
Alexander Kappes
Physics Institute
Univ. Erlangen-Nuremberg
October 14, 2005
LBL, Berkeley
Introduction
The ANTARES Neutrino Telescope
Results from MILOM and Line0
The Future: KM3NeT
Cosmic Radiation
satellites/balloons shower detectors
Discovered in 1912 by
Victor Hess during a
balloon flight
At high energies predominantly
consists of:
protons and a particles
What are the sources
and
acceleration mechanisms?
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 2
Messengers from Deep Space
Magnetic fields
Protons E1019 eV (R~50 Mpc)
Neutrino production:
Reaction of accelerated protons with interstellar medium,
3K microwave background radiation or synchrotron radiation
p + p(g) → p + X
ne : nm : nt ≈ 1 : 2 : 0
9 m + nm
9 e + ne + nm N (n) ≈ N (n)
) observation of n prove for hadron acceleration
Neutrino oscillation results in ne : nm : nt ≈ 1 : 1 : 1
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 3
Detection of Cosmic Neutrinos
Čerenkov light:
Čerenkov angle: 42o
wave lengths used:
350 – 500 nm
Earth used as shield against
all other particles nm A ! m X
low n cross section requires
large detector volumes
n key reaction:
n +N!m +X
m Detector deployed in deep water / ice to
reduce downgoing atmospheric muons
p
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 4
Physics with Neutrino Telescopes High energy limit:
flux decreases with
Low energy limit:
Dark Matter (WIMPs): E-2 … E-3
short m tracks direction, energy
) only few photo Large volumes
sensors give signal required
in sea water: Cosmic point Sources:
40
K + bioluminescence direction, (energy)
give high background
can only be lowered with Diffuse neutrino flux:
energy, (direction)
a denser instrumentation
of the water/ice
GeV TeV PeV EeV En
. . . and also: - GZK neutrinos
- supernova detection
- magnetic monopoles
-...
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 5
Current and Future Neutrino Telescopes
ANTARES
Medium: sea water;
under construction
BAIKAL
Medium: fresh water;
NESTOR
Data since 1991
Medium: sea water;
under construction
AMANDA IceCube
Medium: ice
Data since 1997 under construction
R&D project for km3 detector: NEMO (Mediterranean)
Future project (km3): KM3NeT (Mediterranean)
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 6
Why a telescope in the Mediterranean?
Sky coverage complementary to AMANDA/IceCube
Allows observation of the Galactic Centre
South Pole Mediterranean
Mkn 421
Mkn 501 Mkn 501
not
Crab Crab
visible
SS433 SS433 VELA
not visible Galactic
Centre
Galactic Centre RX J1713
Sources of VHE g emissions (HESS 2005)
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 7
Neutrinos from H.E.S.S. Sources?
Example: SNR RX J1713.7
(shell-type supernova remnant)
Acceleration
beyond 100 TeV.
Power law energy
spectrum, index ~2.1–2.2.
Multi-wavelength spectrum points
to hadron acceleration
) neutrino flux ~ g flux
W. Hofmann, ICRC 2005
Detectable in current and/or
future neutrino telescopes?!
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 8
The ANTARES Collaboration
20 Institutes from
6 European countries
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 9
The ANTARES Detector
Buoy Hostile environment:
pressure up to 240 bar
sea water (corrosion)
Optical
Module
Junction
Submersible Box
artist´s view
(not to scale)
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 10
One of 12 ANTARES Strings
Buoy
keeps string vertical
(horizontal displacement 20% @ 1760 V (360 10 GeV Background (100 kHz)
Cut @ Dxmin 100 TeV;
final parameters (, , E) ) Log-Likelihood fit 60 kHz bckgr per PMT,)
Ni = # photons in PMT i
Results (no cuts): (Preliminary)
Event sample: Instrumented volume 60 kHz bckgr per PMT
# photons absorptionPMT opening angle
+1 length PMT angular
parameterisation
Angular resolution: 10 TeV) efficiency
absorption
of c distribution
but large tails in distributions
Energy resolution: Dlog(E) ¼ 0.1
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 20
Shower Reconstruction with ANTARES
Likelihood in - plane
New idea for minimization strategy:
(Diploma thesis R. Auer)
common to all events: each minimum
lies in broad valley
impose grid on parameter plane (, , E)
and calculate likelihood for centre of tiles
take l tiles with best likelihood values
and divide those into sub-tiles
Results (noL of sub-tiles within one tile
) compare cuts): 60 kHz bckgr
stop after k iterations ( k ¼ 7) and per PMT
Event sample: fully contained events; (Preliminary)
take tile with best likelihood 10 TeV
Line0: mechanical structure water tight and pressure resistant;
losses in optical fibres at interface ) solutions available
Installation of first complete string about Jan. 2006;
Completion of the whole detector until 2007
Well prepared for physics date to come in 2006
KM3NeT: future km3-scale n-telescope in the Mediterranean
km3-scale n telescope on the Northern Hemisphere complementary
to IceCube at the South Pole
3 year EU funded Design Study (~20 M€): expected start beginning 2006
Alexander Kappes October 14, 2005
Univ. Erlangen-Nuremberg LBL, Berkeley 36