Cryogenic system deployed at TUM's (Munich, Germany) shallow underground laboratory Source Ambient Gammas 3.937 Atmospheric Muons 0.019/1.4 0.0134/5 Flux [s-1 cm -2] Atmospheric Neutrons (dominant after vetoing) Searching for Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) with the NUCLEUS detectors Author: Marco Giammei on behalf of the NUCLEUS collaboration Marco Giammei - Ph.D. Candidate - Università di Roma "Tor Vergata" - marco.giammei@roma2.infn.it Coherent Elastic Neutrino Nucleus Scattering (CEvNS) The Experimental Site: VNS at Chooz Nuclear Power Plant Sensitivity and Simulations Interesting Measurements and future plans Active Vetos and Shielding Cryogenic Target Detectors Cryogenic System Very Near Site (VNS): - 24 m2 basement room (~3 m.w.e. overburden) - 30% Muon Attenuation, factor 5 neutron attenuation - Two 4.25 GWth reactors - Anti-Neutrino Flux: ɸ𝜈=1.7×1012 𝜈/cm/s A precision measurement of the CEvNS cross-section oﬀers a unique way to study many neutrino properties and to search for new physics beyond the Standard Model. Direct calibration of nuclear recoils - Neutron absorption followed by de-excitation with high energy 𝛾 emission and nuclear recoil. - Nuclear recoil on CaWO4 expected at 112 eV - Seen with 3σ signiﬁcance using 55Fe calibration Known Backgrounds: - Expected CEvNS rate: • ~30 counts/kg/day in the 10eV-1keV recoil energy range - Targeted Signal/Background ≥ 1 - With 100 dru ﬂat background and full setup: • 5σ signiﬁcance in few weeks of live-time • 10% uncertainty on CEvNS Inner Veto: - Instrumented holder for target detectors: • Sub-keV cryogenic detector with TES readout - Vetos against • Mechanical stress events • "EXCESS" • Surface contamination Muon Veto (MV) : - 5 cm thick plastic scintillator plates - SiPMs & WLS-ﬁber readout - 4π coverage with cryogenic muon veto - Threshold ~ 5 MeV External Shielding: - Lead and Polyethylene Inner Shielding: - Lead, Copper, PE, B4C - Shielding against neutrons and ambient gammas Cryogenic Outer Veto (COV): - Active ionization detectors - Reduction of external ɣ - 4 kg of 2.5 cm thickness in 6 HPGe crystals (4π coverage) - Threshold <10 keV Unknown Background "Low energy EXCESS": - Unexplained exponential rise of counting rate at low energies (similar to reactor CEvNS) - With "EXCESS" competitive limits can be set on new physics models (light mediators or neutrino EM properties) NUCLEUS status and future developments: - Experimental setup being deployed at TUM (Munich, Germany) in shallow underground laboratory for ﬁnal testing and background validation - 2025: setup deployment at Chooz Neutrino Energy Weak Charge Nuclear Form- Factor "Dry" Dilution refrigerator to avoid handling of cryogenic liquids. The base temperature reached is below 7mK. Model: BlueFors LD400 cryogen-free dilution refrigerator Cooling Power: >500 μW at 100mK ✓ Custom Vibration decoupling system deployed and in use (patent protected) ○ Installation of read-out electronics under commissioning ○ Installation of calibration electronics under commissioning Gram-scale cryogenic calorimeters equipped with thin-ﬁlm tungsten transition-edge sensors as highly sensitive thermometers. Optimized to measure energies under a few keV. Two 3x3 matrices of target detectors. Multi-target approach: - Al2O3: for background measurement - CaWO4: high CEvNS rate Transition-Edge Sensor (TES): superconductive ﬁlm operated on the onset of the transition (operated at ~10mK) First combined operation of vetos with target detectors - Muon Veto + One COV crystal + One Al2O3+TES crystal cube - For ~40h of data expected 3-fold coincidences in low background environment (~15 m.w.e): • few direct muons and accidentals (very few in CEvNS's R.O.I) Absorber crystal cube coupled with Source Sum Preliminary 25.8±2.2 55.4±2.1 311.8±9.4 Ambient 𝛾s 3.937 0.019/1.4 0.0134/5.0 (sum) < 1.2 < 7.9 20.9±0.6 0.91±0.18 3.2±1.3 <3.6 39.4±0.9 11.47±0.65 51.4±8.4 10.5±3.5 116.1±1.5 133.8±2.21 Atmospheric muons Atmospheric neutro