Positronium signature in organic liquid scintillators for neutrino experiments

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.83.015504· OSTI ID:21499375

Franco, D ^[1]; Consolati, G ^[2]; Trezzi, D ^[3]

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1. Astroparticule et Cosmologie APC, 10 rue Alice Domon et Leonie Duquet, F-75205 Cedex 13, Paris (France)
2. Dipartimento di Fisica, Politecnico di Milano, Piazzale Leonardo da Vinci 32, I-20133 Milano (Italy)
3. Dipartimento di Fisica, Universita and INFN Milano, via Celoria 16, I-20133 Milano (Italy)

Electron antineutrinos are commonly detected in liquid scintillator experiments via inverse {beta} decay by looking at the coincidence between the reaction products: neutrons and positrons. Prior to positron annihilation, an electron-positron pair may form an orthopositronium (o-Ps) state, with a mean lifetime of a few nanoseconds. Even if the o-Ps decay is speeded up by spin-flip or pick-off effects, it may introduce distortions in the photon emission time distribution, crucial for position reconstruction and pulse shape discrimination algorithms in antineutrino experiments. Reversing the problem, the o-Ps-induced time distortion represents a new signature for tagging antineutrinos in liquid scintillator. In this article, we report the results of measurements of the o-Ps formation probability and lifetime for the most used solvents for organic liquid scintillators in neutrino physics (pseudocumene, linear alkyl benzene, phenylxylylethane, and dodecane). We characterize also a mixture of pseudocumene +1.5 g/l of 2,5-diphenyloxazole, a fluor acting as wavelength shifter. In the second part of the article, we demonstrate that the o-Ps-induced distortion of the scintillation photon emission time distributions represent an optimal signature for tagging positrons on an event by event basis, potentially enhancing the antineutrino detection.

• OSTI ID: 21499375
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 83, Issue 1; Other Information: DOI: 10.1103/PhysRevC.83.015504; (c) 2011 American Institute of Physics; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANNIHILATION
BENZENE
BETA DECAY
DETECTION
DISTRIBUTION
DODECANE
ELECTRON ANTINEUTRINOS
ELECTRONS
LIFETIME
LIQUID SCINTILLATORS
NEUTRONS
PHOTON EMISSION
PLASTIC SCINTILLATORS
POSITRONIUM
POSITRONS
SOLVENTS
SPIN FLIP
WAVELENGTHS
ALKANES
ANTILEPTONS
ANTIMATTER
ANTINEUTRINOS
ANTIPARTICLES
AROMATICS
BARYONS
DECAY
ELECTRON NEUTRINOS
ELEMENTARY PARTICLES
EMISSION
FERMIONS
HADRONS
HYDROCARBONS
INTERACTIONS
LEPTONS
MASSLESS PARTICLES
MATTER
NEUTRINOS
NUCLEAR DECAY
NUCLEONS
ORGANIC COMPOUNDS
PARTICLE INTERACTIONS
PHOSPHORS