The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr).

The Majorana Collaboration is operating an array of high purity Ge detectors to search for the neutrinoless double-beta decay of 76 Ge. The Majorana Demonstrator consists of 44.1 kg of Ge detectors (29.7 kg enriched to 88% in 76 Ge) split between two modules constructed from ultra-clean materials. Both modules are contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota. We present updated results on the search for neutrinoless double-beta decay in 76 Ge with 26.0 ± 0.5 kg-yr of enriched exposure. With the Demonstrator's unprecedented energy resolution of 2.53 keV FWHM at Q ββ , we observe one event in the region of interest with 0.65 events expected from the estimated background, resulting in a lower limit on the 76 Ge neutrinoless double-beta decay half-life of 2.7 × 10 25 yr (90% CL) with a median sensitivity of 4.8 × 10 25 yr (90% CL). Depending on the matrix elements used, a 90% CL upper limit on the effective Majorana neutrino mass in the range of 200-433 meV is obtained. The measured background in the low-background configurations is 11.9 ± 2.0 counts/(FWHM t yr).

No abstract

The electron-ion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the international Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented.

No abstract