8 Neutrino Detectors
357
ARA [65], the Askaryan Radio Array, is a ground based radio array using several
stations of 16 antennas each embeded 200 m deep into the South Pole ice. Three
stations are operational with two more being installed. Each station consists of
four strings separated by 10 m and each consisting of a mixture of horizontal and
vertical polarization antennas. The trigger requires 3 out of 16 signal to exceed a
power threshold within 110 ns. So far, the deployed stations have found no neutrino
candidate including a search centred on 57 GRBs. Ground arrays have also been
proposed on the Ross Ice Shelf, (ARIANNA [66]) and in Greenland (GNO [67]).
This technique has also been extended to neutrino interactions in underground
Rock Salt which allows for better shielding from cosmic rays and also to interactions
in the loose layer of regolith sands on the moon surface. Both of these materials
have attenuation lengths for radio waves of the order of 100 m. While the rock
salt experiments use ground based detectors, the lunar ones, use various radio
telescopes pointed at the lunar limb.The first lunar radio experiment was the Parkes
Lunar Radio Cherenkov experiment [68] and was followed by LUNASKA [69],
GLUE [70] which constrained the neutrino flux above 10 21 eV and NuMooN [71]
which constrained it above 10 23 eV.
Following the good performance of ANTARES off Toulon in the Mediterannean,
a northern hemisphere kilometer cube detector, KM3Net, is currently being implemented [72]. It will consist of two modules. ORCA, at the ANTARES site will
consist of 115 closely packed strings in order to address neutrino oscillations and the
mass hierarchy in the energy range 3–50 GeV. The site will have a diameter of 200 m
and a height of 100 m. ARCA, off Capo Passero in Sicily, will consist of two blocks
of 115 widely spaced strings each block having a diameter of 1 km and a height of
600 m. ARCA’s physics objectives are neutrinos from extra terrestrial sources above
1 TeV and the origin of high energy cosmic rays. Each string of both modules will
consist of 18 optical modules, each housing 31 7.5 cm diameter photomultipliers.
These yield a photocathode area that exceeds by a factor of three that of a single
25 cm photomultiplier, provides some directional information and a good separation
between one and two photoelectron signals.
Lastly a detector,GVD [73],the Gigaton Volume Detector is under construction
at Lake Baikal to observe cosmological neutrinos. It will consist of eight 120 m
diameter clusters of 8 strings each, each string carrying 36 optical modules housing
a 10 Hamamatsu photomultiplier. The cluster separation is 300 m. It is planned to
extend GVD to 18 clusters to make it a cubic kilometer detector.
A detector immersed in the sea in the gulf of Taranto had also been proposed [74]
to study ν μ → ν e oscillations in the then CNGS beam [75], the axis of which was at
a height of 40 km above the surface, thus placing the detector in an off-axis location.
In this case the array of photomultipliers consisted of a vertical plane facing the
beam to observe Cerenkov light from the electrons and muons produced in charged
current interactions and identify them from their light pattern.
357
ARA [65], the Askaryan Radio Array, is a ground based radio array using several
stations of 16 antennas each embeded 200 m deep into the South Pole ice. Three
stations are operational with two more being installed. Each station consists of
four strings separated by 10 m and each consisting of a mixture of horizontal and
vertical polarization antennas. The trigger requires 3 out of 16 signal to exceed a
power threshold within 110 ns. So far, the deployed stations have found no neutrino
candidate including a search centred on 57 GRBs. Ground arrays have also been
proposed on the Ross Ice Shelf, (ARIANNA [66]) and in Greenland (GNO [67]).
This technique has also been extended to neutrino interactions in underground
Rock Salt which allows for better shielding from cosmic rays and also to interactions
in the loose layer of regolith sands on the moon surface. Both of these materials
have attenuation lengths for radio waves of the order of 100 m. While the rock
salt experiments use ground based detectors, the lunar ones, use various radio
telescopes pointed at the lunar limb.The first lunar radio experiment was the Parkes
Lunar Radio Cherenkov experiment [68] and was followed by LUNASKA [69],
GLUE [70] which constrained the neutrino flux above 10 21 eV and NuMooN [71]
which constrained it above 10 23 eV.
Following the good performance of ANTARES off Toulon in the Mediterannean,
a northern hemisphere kilometer cube detector, KM3Net, is currently being implemented [72]. It will consist of two modules. ORCA, at the ANTARES site will
consist of 115 closely packed strings in order to address neutrino oscillations and the
mass hierarchy in the energy range 3–50 GeV. The site will have a diameter of 200 m
and a height of 100 m. ARCA, off Capo Passero in Sicily, will consist of two blocks
of 115 widely spaced strings each block having a diameter of 1 km and a height of
600 m. ARCA’s physics objectives are neutrinos from extra terrestrial sources above
1 TeV and the origin of high energy cosmic rays. Each string of both modules will
consist of 18 optical modules, each housing 31 7.5 cm diameter photomultipliers.
These yield a photocathode area that exceeds by a factor of three that of a single
25 cm photomultiplier, provides some directional information and a good separation
between one and two photoelectron signals.
Lastly a detector,GVD [73],the Gigaton Volume Detector is under construction
at Lake Baikal to observe cosmological neutrinos. It will consist of eight 120 m
diameter clusters of 8 strings each, each string carrying 36 optical modules housing
a 10 Hamamatsu photomultiplier. The cluster separation is 300 m. It is planned to
extend GVD to 18 clusters to make it a cubic kilometer detector.
A detector immersed in the sea in the gulf of Taranto had also been proposed [74]
to study ν μ → ν e oscillations in the then CNGS beam [75], the axis of which was at
a height of 40 km above the surface, thus placing the detector in an off-axis location.
In this case the array of photomultipliers consisted of a vertical plane facing the
beam to observe Cerenkov light from the electrons and muons produced in charged
current interactions and identify them from their light pattern.