Full background decomposition of the CONUS experiment

Abstract

The CONUS experiment is searching for coherent elastic neutrino nucleus scattering of reactor anti-neutrinos with four low energy threshold point-contact high-purity germanium spectrometers. An excellent background suppression within the region of interest below 1keV (ionization energy) is absolutely necessary to enable a signal detection. The collected data also make it possible to set limits on various models regarding beyond the standard model physics. These analyses benefit as well from the low background level of ~10d${}^{-1}$kg${}^{-1}$below 1keV and at higher energies. The low background level is achieved by employing a compact shell-like shield, that was adapted to the most relevant background sources at the shallow depth location of the experiment: environmental gamma-radiation and muon-induced secondaries. Overall, the compact CONUS shield including the active anti-coincidence muon-veto reduces the background by more than four orders of magnitude. The remaining background is described with validated Monte Carlo simulations which include the detector response. It is the first time that a full background decomposition in germanium operated at reactor-site has been achieved. Next to remaining muon-induced background, ${}^{210}$Pb within the shield and cryostat end caps, cosmogenic activation and air-borne radon are the most relevant background sources. The reactor-correlated background is negligible within the shield. The validated background model together with the parameterization of the noise are used as input to the likelihood analyses of the various physics cases.

27 pages, 21 figures

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• \textsc{MaGe} - a {\sc Geant4}-based Monte Carlo Application Framework for Low-background Germanium Experiments
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• Measurement of the low-energy quenching factor in germanium using an ${}^{88}$Y/Be photoneutron source
• First upper limits on neutrino electromagnetic properties from the CONUS experiment
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• Cosmogenic activation of materials
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Cited by in corpus (8)

• Novel constraints on neutrino physics beyond the standard model from the CONUS experiment
• Direct observation of coherent elastic antineutrino-nucleus scattering
• Final CONUS results on coherent elastic neutrino-nucleus scattering at the Brokdorf reactor
• New constraints on coherent elastic neutrino-nucleus scattering by the nuGeN experiment
• Pulse shape discrimination for the CONUS experiment in the keV and sub-keV regime
• Light vector bosons and the weak mixing angle in the light of future germanium-based reactor CE$\nu$NS experiments
• Particle background characterization and prediction for the NUCLEUS reactor CE$\nu$NS experiment
• Testing lepton non-unitarity with the next generation of Germanium-based CE$\nu$NS reactor experiments