News & Events

Wednesday, 6 June 2018

Neutrino 2018 conference keeps going and today in the morning session of its third day, the last results and/or updates on some of the main neutrinoless double beta decay experiments such as EXO, KamLAND-Zen, GERDA, MAJORANA and CUORE have been reported. In particular, the Gerda and MAJORANA collaborations have presented novel results.

The EXO experiment uses 136Xe to look for the very rare process of neutrinoless double beta decay. EXO-200 has set a present limit on T^1/2 of 1.8×10²⁵ years with an effective Majorana mass m_ββ of (147,398) meV. nEXO, the proposed future upgrade of this experiment, will have an expected sensitivity on T^1/2 ​of 9.2×10²⁷ years, entirely covering the inverted hierarchy effective Majorana mass range and with substantial sensitivity to the normal one.

The KamLAND-Zen collaboration has reviewed its results after combining phase I and phase II of KamLAND-Zen 400, with a limit on T^1/2 of 1.07×10²⁶ years and a corresponding sensitivity on the effective mass range of (61,165) meV. Its upgrade, KamLAND-Zen 800, which will start taking data this year, is expected to reach a sensitivity to the effective electron Majorana neutrino mass of 40 meV.


The phase II of GERDA experiment studied instead 76Ge with total exposure of  82.4 kg year, and has set a limit on T^1/2 of 0.9×10²⁶ years, which corresponds to a limit on m_ββ < (110, 260) meV.

The MAJORANA DEMONSTRATOR experiment has set a limit on T^1/2 of 2.2×10²⁵ years which implies m_ββ < (200, 433) meV.

The CUORE collaboration has reported its latest results using 130Te, setting a limit of 1.5×10²⁵ years, which corresponds to m_ββ < (110,520) meV. Details can be found in their paper.

A review on the present status and the future prospects of the main 0νββ-decay experiments has been summarised by Andrea Giuliani.

Finally, during the neutrino astronomy session in the afternoon, the present status and future perspectives of neutrino telescopes, like IceCube and ANTARES, have been addressed. IceCube has shown preliminary results with 7.5 yr data after reviewing systematic uncertainties and calibration. The data sample consists of 103 events, among which 60 events have energies above 60 TeV, with a best-fit power law of E^-2.87. No evidence for point sources nor a correlation with the galactic plane is found and two double cascades have been identified. The flavor composition best-fit lies at 0.35:0.45:0.2. These experiments are critical for multi-messenger studies of astrophysical objects at high energies.

Follow the conference and these very interesting results at the conference website.

Text by Olga Mena, Xabier Marcano, Josu Hernández-García, Álvaro Hernández-Cabezudo & Bruno Martín.