Development of a compact muon veto for the nucleus experiment

The Nucleus experiment aims to measure coherent elastic neutrino nucleus scattering of reactor anti-neutrinos using cryogenic calorimeters. Operating at an overburden of 3 meters of water equivalent, muon-induced backgrounds are expected to be one of the dominant background contributions. Besides a high efficiency to identify muon events passing the experimental setup, the Nucleus muon veto has to fulfill tight spatial requirements to fit the constraints given by the experimental site and to minimize the induced detector dead-time. We developed highly efficient and compact muon veto modules based on plastic scintillators equipped with wavelength shifting fibers and silicon photo multipliers to collect and detect the scintillation light. In this paper, we present the full characterization of a prototype module with different light read-out configurations. We conclude that an efficient and compact muon veto system can be built for the Nucleus experiment from a cube assembly of the developed modules. Simulations show that an efficiency for muon identification of >99 % and an associated rate of 325 Hz is achievable, matching the requirements of the Nucleus experiment

Observation of a nuclear recoil peak at the 100 eV scale induced by neutron capture

Coherent elastic neutrino-nucleus scattering and low-mass Dark Matter detectors rely crucially on the understanding of their response to nuclear recoils. We report the first observation of a nuclear recoil peak at around 112 eV induced by neutron capture. The measurement was performed with a CaWO$_4$ cryogenic detector from the NUCLEUS experiment exposed to a $^{252}$Cf source placed in a compact moderator. The measured spectrum is found in agreement with simulations and the expected peak structure from the single-$\gamma$ de-excitation of $^{183}$W is identified with 3 $\sigma$ significance. This result demonstrates a new method for precise, in-situ, and non-intrusive calibration of low-threshold experiments

Coherent elastic neutrino-nucleus scattering: Terrestrial and astrophysical applications

Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) is a process in which neutrinos scatter on a nucleus which acts as a single particle. Though the total cross section is large by neutrino standards, CE$\nu$NS has long proven difficult to detect, since the deposited energy into the nucleus is $\sim$ keV. In 2017, the COHERENT collaboration announced the detection of CE$\nu$NS using a stopped-pion source with CsI detectors, followed up the detection of CE$\nu$NS using an Ar target. The detection of CE$\nu$NS has spawned a flurry of activities in high-energy physics, inspiring new constraints on beyond the Standard Model (BSM) physics, and new experimental methods. The CE$\nu$NS process has important implications for not only high-energy physics, but also astrophysics, nuclear physics, and beyond. This whitepaper discusses the scientific importance of CE$\nu$NS, highlighting how present experiments such as COHERENT are informing theory, and also how future experiments will provide a wealth of information across the aforementioned fields of physics

Coherent elastic neutrino-nucleus scattering: Terrestrial and astrophysical applications

Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) is a process inwhich neutrinos scatter on a nucleus which acts as a single particle. Thoughthe total cross section is large by neutrino standards, CE$\nu$NS has longproven difficult to detect, since the deposited energy into the nucleus is$\sim$ keV. In 2017, the COHERENT collaboration announced the detection ofCE$\nu$NS using a stopped-pion source with CsI detectors, followed up thedetection of CE$\nu$NS using an Ar target. The detection of CE$\nu$NS hasspawned a flurry of activities in high-energy physics, inspiring newconstraints on beyond the Standard Model (BSM) physics, and new experimentalmethods. The CE$\nu$NS process has important implications for not onlyhigh-energy physics, but also astrophysics, nuclear physics, and beyond. Thiswhitepaper discusses the scientific importance of CE$\nu$NS, highlighting howpresent experiments such as COHERENT are informing theory, and also how futureexperiments will provide a wealth of information across the aforementionedfields of physics.<br

Development of a compact muon veto for the Nucleus experiment

International audienceThe Nucleus experiment aims to measure coherent elastic neutrino nucleus scattering of reactor anti-neutrinos using cryogenic calorimeters. Operating at an overburden of 3 meters of water equivalent, muon-induced backgrounds are expected to be one of the dominant background contributions. Besides a high efficiency to identify muon events passing the experimental setup, the Nucleus muon veto has to fulfill tight spatial requirements to fit the constraints given by the experimental site and to minimize the induced detector dead-time. We developed highly efficient and compact muon veto modules based on plastic scintillators equipped with wavelength shifting fibers and silicon photo multipliers to collect and detect the scintillation light. In this paper, we present the full characterization of a prototype module with different light read-out configurations. We conclude that an efficient and compact muon veto system can be built for the Nucleus experiment from a cube assembly of the developed modules. Simulations show that an efficiency for muon identification of >99 % and an associated rate of 325 Hz is achievable, matching the requirements of the Nucleus experiment

Exploring CEν\nuNS of reactor neutrinos with the NUCLEUS experiment

International audienceCoherent elastic neutrino-nucleus scattering (CEνNS) offers a unique way to study neutrino properties and to search for new physics beyond the Standard Model. The NUCLEUS experiment aims to measure CEνNS of reactor anti-neutrinos down to unprecedented low nuclear recoil energies. The novel gram-scale cryogenic detectors feature an ultra-low energy threshold of ≤20eV$_{nr}$ and a rise time of a few 100 μs which allows the operation above ground. The fiducialization of the detectors provides an effective discrimination of ambient γ- and surface backgrounds. Furthermore, the use of multiple targets promises a high physics potential. The NUCLEUS experiment will be located at a new experimental site at the Chooz nuclear power plant in France, providing a high anti-neutrino flux of . The commissioning of the experimental setup with a comprehensive background measurement is planned for 2022

Exploring coherent elastic neutrino-nucleus scattering of reactor neutrinos with the NUCLEUS experiment

International audienceThe NUCLEUS experiment aims to perform a high-precision measurement of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) at the EdF Chooz B nuclear power plant in France. CEvNS is a unique process to study neutrino properties and to search for physics beyond the Standard Model. The study of CEvNS is also important for light Dark-Matter searches. It could be a possible irreducible background for high-sensitivity Dark-Matter searches. NUCLEUS is an experiment under construction based on ultra-low threshold (20 eVnr) cryogenic calorimeters, operated at tens-of-mK temperatures

The NUCLEUS experiment: a search for coherent elastic neutrino-nucleus scattering with reactor antineutrinos

International audienceCoherent elastic neutrino-nucleus scattering (CE$\nu$NS) offers a unique way to study neutrino properties and to search for new physics beyond the Standard Model. The NUCLEUS experiment aims at measuring the CE$\nu$NS signal from reactor antineutrinos using newly developed cryogenic detectors with ultra-low recoil energy threshold. The experiment is currently under construction for a blank assembly and later planned to be installed in between the two 4.25 GW$_{\text{th}}$ nuclear reactors of the Chooz B power plant in the French Ardennes. This proceeding presents an overview of the first phase of the NUCLEUS experiment. A general description of the experimental apparatus and its expected sensitivity to the CE$\nu$NS is provided

Nucleus: searching for coherent neutrino nucleus scattering at lowest energies

Coherent neutrino-nucleus scattering is a promising new tool in the toolbox of electroweak precision measurements at low q-transfer. It will enable precise measurements of standard model (SM) physics like the running of the Weinberg angle but also the search for new physics beyond the SM like sterile neutrinos. The Nucleus experiment aims at the first detection of fully coherent neutrino-nucleus scattering at the Chooz power plant in France, using its two 4GWth reactor cores as high-intensity source for anti-neutrinos. For this endeavour a new experimental site, the Very Near Site (VNS), with a shallow rock overburden of ≈ 3 m&nbsp;w.e. is under development. To be competitive in this challenging environment, Nucleus developed the novel concept of fiducialised cryogenic bolometers based on CaWO4 monocrystals operated at O(10 mK). The signature of a coherent neutrino-nucleus scattering is a nuclear recoil at the 10 eV-scale. Currently, Nucleus is preparing its first phase with 10 g of target mass at the VNS. In this contribution, we will first introduce Nucleus, report its current state and give an outlook to its future

NUCLEUS: cryogenic calorimeters to detect coherent nuclear scattering of reactor antineutrinos

International audienceNUCLEUS is an experiment conceived for the detection of thecoherent elastic neutrino nucleus scattering. The experiment will be carried out in the nuclear power plant of Chooz-B in France that provides an intense flux of anti-neutrinos.The aim of NUCLEUS is to perform a very precise measurement of the coherent elastic scattering below 100 eV by employing extremely sensitive cryogenic detectors based on CaWO$_4$ and Al$_2$O$_3$ target crystals.At present, the NUCLEUS apparatus is in commissioning phaseat the Underground Laboratory of the Technical University Munich, where - after its installation and the first measurement phase - the experiment will be fully tested. Thereafter the entire apparatus will be moved to the reactor site at Chooz