NUCLEUS: Exploring Coherent Neutrino-Nucleus Scattering with Cryogenic Detectors

Abstract

The NUCLEUS experiment aims for the detection of coherent elastic neutrino-nucleus scattering at a nuclear power reactor with gram-scale, ultra-low-threshold cryogenic detectors. This technology leads to a miniaturization of neutrino detectors and allows to probe physics beyond the Standard Model of particle physics. A 0.5 g NUCLEUS prototype detector, operated above ground in 2017, reached an energy threshold for nuclear recoils of below 20 eV. This sensitivity is achieved with tungsten transition edge sensors which are operating at temperatures of 15 mK and are mainly sensitive to non-thermal phonons. These small recoil energies become accessible for the first time with this technology, which allows collecting large-statistics neutrino event samples with a moderate detector mass. A first-phase cryogenic detector array with a total mass of 10 g enables a 5-sigma observation of coherent scattering within several weeks. We identified a suitable experimental site at the Chooz Nuclear Power Plant and performed muon and neutron background measurements there. The operation of a NUCLEUS cryogenic detector array at such a site requires highly efficient background suppression. NUCLEUS plans to use an innovative technique consisting of separate cryogenic anticoincidence detectors against surface backgrounds and penetrating (gamma, neutron) radiation. We present first results from prototypes of these veto detectors and their operation in coincidence with a NUCLEUS target detector.

Probing Active-Sterile Neutrino Transition Magnetic Moments with Photon Emission from CE$ν$NS

“…In this Letter, we explore the feasibility of detecting the radiative upscattering process at CEνNS experiments. In particular we consider the NUCLEUS experiment [3,4] located at the CHOOZ reactor facility as a case study, with its current experimental set up and planned future upgrade providing a realistic possibility of detecting the outgoing photon energy and angle distributions [20]. We demonstrate that the identification of a differential distribution consistent with either a sterile Dirac or Majorana heavy neutral lepton can provide important implications towards the outstanding questions of the nature and mass generation mechanism of active neutrinos.…”

“…The future CEνNS experiments promise unprecedented sensitivities in detecting nuclear recoil with small energy transfer due to the extremely low-recoil threshold (as low as eV) achieved experimentally [3,4]. Therefore, these future generation experiments will not only test the SM prediction more precisely, but also search for the presence of new physics (NP) beyond the SM.…”

Identification of the low energy excess in dark matter searches with crystal defects

“…To test if the excess events are due to nuclear recoils, we propose to use a diamond detector. For a quantitative analysis, we use as a template for the unidentified low energy event rate the data from Nucleus 1g prototype [17], shown in figure 1, reproduced here using the data repository [29]. We will parametrize this data using a twocomponent fit, with an exponential and a power law component, of the form Based on MD simulation data from [26], diamond has a very sharp threshold for defect creation, resulting in a step-like rise in the average energy loss as a function of recoil energy, shown in figure 2.…”

“…We propose to use the sharp defect creation threshold of diamond to test if the low energy events are due to nuclear recoils. Based on simulated data we expect the nuclear recoil bump in the observed spectrum to be visible in diamond with just ∼ 0.1 gram days of exposure.Recently several experiments [11][12][13][14][15][16][17][18][19][20] have observed a steeply rising event rate at low energies, E r 1000 eV. The origin of these…”

“…Recently several experiments [11][12][13][14][15][16][17][18][19][20] have observed a steeply rising event rate at low energies, E r 1000 eV. The origin of these…”