Solar neutrinoelectron scattering as background limitation for double-beta decay N F de Barros, K Zuber
To cite this version:
N F de Barros, K Zuber. Solar neutrinoelectron scattering as background limitation for double-beta decay. Journal of Physics G: Nuclear and Particle Physics, IOP Publishing, 2011, 38 (10), pp.105201. 10.1088/0954-3899/38/10/105201. hal-00655650
HAL Id: hal-00655650 https://hal.archives-ouvertes.fr/hal-00655650 Submitted on 1 Jan 2012
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19 July 2011
Solar neutrino-electron scattering as background limitation for double beta decay
NFdeBarros,KZuber Institut f¨ur Kern- und Teilchenphysik, Technische Universit¨at Dresden, Zellescher Weg 19, 01062 Dresden, Germany E-mail: [email protected], [email protected]
Abstract. The background on double beta decay searches due to elastic electron scattering of solar neutrinos of all double beta emitters with Q-value larger than 2 MeV is calculated, taking into account survival probability and flux uncertainties of solar neutrinos. This work determines the background level to be 1 − 2 × 10−7 counts keV −1kg−1yr−1,dependingonthepreciseQ-valueofthedoublebetaemitter.Itis also shown that the background level increases dramatically if going to lower Q-values. Furthermore, studies are done for various detector systems under consideration for next generation experiments. It was found that experiments based on loaded liquid scintillator have to expect a higher background. Within the given nuclear matrix element uncertainties any approach exploring the normal hierarchy has to face this irreducible background, which is a limitation on the minimal achievable background for purely calorimetric approaches. Large scale liquid scintillator experiments might encounter this problem already while exploring the inverted hierarchy. Potential caveats by using more sophisticated experimental setups are also discussed. Solar neutrino-electron scattering as background limitation for double beta decay 2
1. Introduction
In the last decade the field of non-accelerator particle physics and particle astrophysics has made major progress and is now considered to be a reliable research area complementary to high energy accelerator physics. Aspecialsubsetisthefieldoflowbackgroundphysics,searchingforextremelyrare events normally hidden in an overwhelming large background. Best examples for this scenario are dark matter searches and neutrino physics. As part of this, it is one of the big achievements of the last decade that the observation of neutrino oscillations have shown the existence of a non-vanishing rest mass of the neutrinos. It is known that the problem of missing solar neutrinos can be explained by matter effects which is confirmed by the KamLAND reactor experiment [1, 2, 3]. Additionally, also the atmospheric neutrino anomaly observed in water Cerenkovˇ detectors like Super-Kamiokande has been confirmed by long baseline accelerator experiments [4, 5]. All evidences can be converted into quantities of the PMNS mixing matrix elements linking weak and mass 2 2 2 2 eigenstates given by ∆m12 ,sin 2θ12 ,∆m13 and sin 2θ13 . However, neutrino oscillations do not fix the absolute neutrino mass scale, thus leaving two possible scenarios open: almost degenerate neutrinos, a valid scenario if the neutrino mass is larger than about 100 meV, or a hierarchical structure if the mass is smaller. The latter can be split in a normal (m1 (m3