GENIUS - a Supersensitive Germanium Detector System for Rare Events

TL;DR

GENIUS introduces a supersensitive germanium detector system that operates naked Ge crystals immersed in ultrapure liquid nitrogen shielding in an underground setting to dramatically reduce backgrounds. The 100 kg natural Ge stage targets direct dark matter detection and real-time solar neutrinos, while a future 1 ton (or more) enriched Ge stage aims for neutrinoless double beta decay sensitivity to $\langle m_\nu \rangle$ down to $0.01$ eV, enabling exploration of wide beyond-Standard-Model physics including SUSY, leptoquarks, and left–right symmetries. The work provides comprehensive background simulations, detector-technological feasibility, and a full facility design showing that GENIUS could surpass many existing terrestrial experiments in sensitivity and offer complementary insights to collider searches. It also presents a realistic path to measuring solar pp and $^7$Be neutrinos in real time, contingent on achieving ultra-low backgrounds and controlling cosmogenic activation. Overall, GENIUS represents a transformative approach to rare-event detection with broad implications for dark matter, neutrino physics, and new physics at multi-TeV scales.

Abstract

To increase by a major step the present sensitivity for dark matter and double beta decay search, a new project is suggested, which would operate 'naked' GErmanium detectors in liquid NItrogen as shielding in an Underground Setup (GENIUS). In a first step using 100 kg of natural Ge a large part of the MSSM parameter space for prediction of neutralinos as cold dark matter will be covered making the experiment complementary to LHC in the search for supersymmetry. In the second step use of one ton of enriched 76Ge would yield a sensitivity for double beta decay for the effective Majorana neutrino mass of \0.01 eV. This would be a breakthrough for neutrino physics. GENIUS would also be a breakthrough into the multi-TeV range for many other beyond standard models currently discussed, and the sensitivity would be comparable or even superior to LHC or NLC for various quantities such as right-handed W boson mass, R-parity violation, leptoquark or compositeness searches, or left-handed heavy neutrinos.

Figures (55)

• Figure 1: Summary of an overall accounting of matter and energy in the Universe, from turner99
• Figure 2: Total measured spectrum with one enriched $^{76}$Ge detector of the Heidelberg-Moscow experiment after an exposure of 0.69 kg yr and a theoretical spectrum for a 100 GeV WIMP.
• Figure 3: Schematic figure of the HDMS detector.
• Figure 4: The HDMS detector during its installation in the Gran Sasso Laboratory.
• Figure 5: WIMP--nucleon cross section limits as a function of the WIMP mass. The hatched region is excluded by the Heidelberg--Moscow HM98 and the DAMA experiment DAMA, the dashed lines are expectations for recently started or future experiments, like HDMS Bau97, CDMS cdms98 and CRESST cresst96. The filled contour represents the 2$\sigma$ evidence region of the DAMA experiment damaevid. The solid fat line denotes the expectation for the GENIUS project with a background level of 0.01 counts/(keV kg y), an energy threshold of 11 keV and an exposure of 300 kg yr. The experimental limits are compared to expectations (scatter plot) for WIMP--neutralinos calculated in the MSSM framework with non--universal scalar mass unification Bed97c.