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Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 1999-08, Vol.433 (1), p.104-120
Ort / Verlag
Elsevier B.V
Erscheinungsjahr
1999
Quelle
Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)
Beschreibungen/Notizen
We describe a 125
m diameter spherical detector containing 1
Mt of water, capable of high rate observation of atmospheric neutrino events (30 000/y). The ring imaging Cherenkov (RICH) technique is used to measure velocity, momentum and direction of particles produced by neutrinos interacting in water. The detector will be sited outdoors (under a 50
m water shield) in a natural (further excavated) pit, probably in Sicily.
Spherical reflecting mirrors focus Cherenkov light produced by secondaries from interacting neutrinos. Photons are detected by 5310 hybrid photodiodes (HPDs) of 1
m diameter each with 396 pads of 45×45
mm
2 on the photocathode surface, demagnified to 9×9
mm
2 on the silicon sensor. For most tracks the ring width will be dominated by multiple scattering which should allow momentum to be determined. Hadrons of momentum
p≤5
GeV/
c can be measured with
σ
p
/
p≤7% and muons of
p≤32
GeV/
c with
σ
p
/
p≤1%. The ring center determines track direction with
σ
θx,
σ
θy≈6
mrad. Track reconstruction in water will require time resolution
σ
t
<1
ns.
Detection of oscillating muon signals (disappearance) is feasible with atmospheric neutrinos and precision measurement of oscillation parameters is feasible for 10
−2≤Δ
m
2≤10
−4eV
2. Tau or sterile neutrino appearance experiments are also possible with atmospheric neutrinos. Other physics topics addressable with this detector are proton decay, supernova detection and search for astrophysical neutrino sources.
A first test module of 3 tons water and 120
PMs (32
mm φ) will operate (5/99) with 1–3
GeV muons in a CERN-PS test beam to verify the momentum algorithm. A second (6
m)
3 test module with 216 tons of water and 25 HPDs (0.25
m φ) is designed to observe full multi-track images and test pattern recognition and ring reconstruction algorithms.