Eur. Phys. J. C (2016) 76: 550
https://doi.org/10.1140/epjc/s10052-016-4406-0

Regular Article - Theoretical Physics

Probing neutrino nature at Borexino detector with chromium neutrino source

Institute of Theoretical Physics, University of Wrocław, Pl. M. Born 9, 50-204, Wrocław, Poland

^* e-mail: wieslaw.sobkow@ift.uni.wroc.pl

Received: 13 July 2016
Accepted: 26 September 2016
Published online: 6 October 2016

Abstract

In this paper, we indicate a possibility of utilizing the intense chromium source (370  PBq) in probing the neutrino nature in low energy neutrino experiments with the ultra-low threshold and background real-time Borexino detector located near the source (8 m). We analyse the elastic scattering of electron neutrinos (Dirac or Majorana, respectively) on the unpolarised electrons in the relativistic neutrino limit. We assume that the incoming neutrino beam is the superposition of left–right chiral states produced by the chromium source. Left chiral neutrinos may be detected by the standard and non-standard scalar , pseudoscalar , tensor interactions, while right chiral ones partake only in the exotic and interactions. Our model-independent study is carried out for the flavour (current) neutrino eigenstates. We compute the expected event number for the standard interaction of the left chiral neutrinos using the current experimental values of standard couplings and in the case of left–right chiral superposition. We show that the significant decrement in the event number due to the interference terms between the standard and exotic interactions for the Majorana neutrinos may appear. We also demonstrate how the presence of the exotic couplings affects the energy spectrum of outgoing electrons, both for the Dirac and Majorana cases. The C.L. sensitivity contours in the planes of corresponding exotic couplings are found. The presence of interferences in the Majorana case gives the stronger constraints than for the Dirac neutrinos, even if the neutrino source is placed outside the detector.