Neutrinoless double beta decay is a process that violates lepton number conservation. It is predicted to occur in extensions of the standard model of particle physics. This Letter reports the results from phase I of the Germanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (Italy) searching for neutrinoless double beta decay of the isotope ${}^{76}\mathrm{Ge}$. Data considered in the present analysis have been collected between November 2011 and May 2013 with a total exposure of 21.6 kg yr. A blind analysis is performed. The background index is about $1\times {10}^{-2}\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$ after pulse shape discrimination. No signal is observed and a lower limit is derived for the half-life of neutrinoless double beta decay of ${}^{76}\mathrm{Ge}$, $T_{1/2}^{0\nu }>2.1\times {10}^{25}\mathrm{yr}$ (90% C.L.). The combination with the results from the previous experiments with ${}^{76}\mathrm{Ge}$ yields $T_{1/2}^{0\nu }>3.0\times {10}^{25}\mathrm{yr}$ (90% C.L.).

The Gerda collaboration is performing a search for neutrinoless double beta decay of 76Ge with the eponymous detector. The experiment has been installed and commissioned at the Laboratori Nazionali...

This Letter reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 ton day) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage $<1.2\times {10}^{-7}$ (90% C.L.) between 15 and $31{\mathrm{keV}}_{ee}$. No candidate signal events are observed, which results in the leading limit on weakly interacting massive particle (WIMP)-nucleon spin-independent cross section on argon, $<1.2\times {10}^{-44}{\mathrm{cm}}^2$ for a $100\mathrm{GeV}/c^2$ WIMP mass (90% C.L.).

We report an improved geoneutrino measurement with Borexino from 2056 days of data taking. The present exposure is $(5.5\pm 0.3)\times {10}^{31}\mathrm{proton}\times \mathrm{yr}$. Assuming a chondritic Th/U mass ratio of 3.9, we obtain ${23.7}_{-5.7}^{+6.5}(\text{stat}{)}_{-0.6}^{+0.9}(\text{sys})$ geoneutrino events. The null observation of geoneutrinos with Borexino alone has a probability of $3.6\times {10}^{-9}$ ($5.9\sigma$). A geoneutrino signal from the mantle is obtained at 98% C.L. The radiogenic heat production for U and Th from the present best-fit result is restricted to the range 23–36 TW, taking into account the uncertainty on the distribution of heat producing elements inside the Earth.