The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)

Abstract

Abstract. The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neutrinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 − 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76 Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76 Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 10 28 years, using existing resources as appropriate to expedite physics results.

Flavour and CP predictions from orbifold compactification

“…One sees that m ββ is determined within rather small errors, and presents a challenge for the next generation of 0νββ searches. For comparison, the top green horizontal band in Figure 2 represents the current experimental limits from Kamland-Zen (61 − 165 meV) [33], while the dashed horizontal lines correspond to the projected most optimistic sensitivities from LEGEND (10.7 − 22.8 meV) [34], SNO + Phase II (19 − 46 meV) [35], and nEXO (5.7 − 17.7 meV) [36].…”

A theory for scotogenic dark matter stabilised by residual gauge symmetry

“…The widths of these bands reflect uncertainties in nuclear matrix elements. The lower bands show the future sensitives from LEGEND (10.7 − 22.8 meV) [39], SNO + Phase II (19 − 46 meV) [40] and nEXO (5.7 − 17.7 meV) [41].…”

Fabrication and characterization of high-purity germanium detectors with amorphous germanium contacts

“…Commercially available large HPGe crystals (up to 10 cm in diameter) enhance the probability of total absorption of an incoming gamma ray in the crystal leading to a high detection efficiency [18][19]. Currently, HPGe crystals are not only the best choice of material for gamma-ray spectroscopy but also a well-accepted technology for rare event physics in the search for dark matter [12][13][20][21] and neutrinoless double-beta decay [22][23][24][25][26][27][28][29]. Therefore, HPGe detectors have been used in several research projects, including CoGeNT [30][31], SuperCDMS [32][33][34], EDELWEISS [35][36][37], GERDA [38][39][40], MAJORANA DEMONSTRATOR [41][42], CDEX [21,[43][44], focused on detecting dark matter or neutrinoless double-beta decay.…”