Abe2014_Article_Ortho-positroniumObservationIn.pdf (573.62 kB)
Ortho-positronium observation in the double chooz experiment
journal contribution
posted on 2023-06-10, 01:46 authored by Y Abe, J C Dos Anjos, J C Barriere, E Baussan, I Bekman, M Bergevin, Thiago Sogo BezerraThiago Sogo Bezerra, L Bezrukov, E Blucher, C Buck, J Busenitz, A Cabrera, E Caden, L Camilleri, R Carr, The Double Chooz collaboration, othersThe Double Chooz experiment measures the neutrino mixing angle ?13 by detecting reactor ¯?e via inverse beta decay. The positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless liquid scintillator detectors would profit from a positron/electron discrimination, if feasible in large detector, to suppress the remaining background. Standard particle identification, based on particle dependent time profile of photon emission in liquid scintillator, can not be used given the identical mass of the two particles. However, the positron annihilation is sometimes delayed by the orthopositronium (o-Ps) metastable state formation, which induces a pulse shape distortion that could be used for positron identification. In this paper we report on the first observation of positronium formation in a large liquid scintillator detector based on pulse shape analysis of single events. The o-Ps formation fraction and its lifetime were measured, finding the values of 44 % ± 12 % (sys.) ± 5 % (stat.) and 3.68 ns ± 0.17 ns (sys.) ± 0.15 ns (stat.) respectively, in agreement with the results obtained with a dedicated positron annihilation lifetime spectroscopy setup.
History
Publication status
- Published
File Version
- Published version
Journal
Journal of High Energy PhysicsISSN
1126-6708Publisher
SpringerExternal DOI
Volume
2014Page range
1-14Article number
a32Department affiliated with
- Physics and Astronomy Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2021-11-16First Open Access (FOA) Date
2021-11-16First Compliant Deposit (FCD) Date
2021-11-12Usage metrics
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