arXiv subjects

D. Piani

Publications and source records attributed to D. Piani.

3 recordsLinked to original sources

arXiv2026

Background decomposition of the CONUS+ run 1 data

The CONUS+ experiment is measuring the coherent elastic neutrino nucleus scattering (CE$\nu$NS) process using reactor anti-neutrinos as a source and four low energy threshold point-contact high-purity germanium spectrometers for their detection. It achieved the first measurement of coherent neutrino scattering at a nuclear reactor in run 1 of the experiment with a detection energy threshold of 160 eV$_{ee}$. This work presents the decomposition of the background spectra of the three detectors used in the run 1 analysis and the development of the corresponding background model with Geant4-based Monte Carlo simulations. The background model is used as the underlying input for the likelihood fit of the analysis. It is shown that reactor-correlated backgrounds are subdominant in all energy regions, specifically in the region of interest for CE$\nu$NS searches below 350 eV$_{ee}$ where their contribution is one order of magnitude below the expected CE$\nu$NS signal. Furthermore, cosmic ray muons and neutrons are identified as the dominant background source below 1 keV$_{ee}$ contributing approximately 75 - 90 \% of the recorded background rate. The final background model predicts an average rate of (47.5 $\pm$ 3.2) d$^{-1}$ kg$^{-1}$ in reactor on measurement in the energy region between [0.4, 1.0] keV$_{ee}$, which is in excellent agreement with the average measured value of (48.0 $\pm$ 0.6) d$^{-1}$ kg$^{-1}$. Similar agreement is found in all energy regions of both reactor on and off measurements.

physics.ins-det↗

arXiv2026

New constraints on physics within and beyond the standard model from the latest CONUS datasets

Its detections with pion-decay-at-rest, solar and recently with reactor antineutrinos by the CONUS collaboration render coherent elastic neutrino-nucleus scattering (CE$\nu$NS) an established tool for investigations within and beyond the Standard Model (SM). The CONUS experiment located at the nuclear power plants in Brokdorf (Germany) and Leibstadt (Switzerland) operates Germanium semiconductor detectors in a compact shield at close distance to the reactor core. An observation with $3.7 \sigma$ significance is reported at the Leibstadt site, showing good agreement with its SM prediction. Physics investigations performed with the last datasets collected at the Brokdorf reactor and with the first data obtained at the Leibstadt site are summarized. By using the experimental analysis framework, the presented results contain the full systematics that underlie the experiment. Previously determined limits with neutrino-electron scattering on the neutrino magnetic moment and a neutrino millicharge are improved to $\mu_{\nu} <5.18\cdot 10^{-11}\mu_\mathrm{B}$ and $q_{\nu}<1.76\cdot 10^{-12} e_0$ (90% C.L). Further, the scale of new physics related to NSIs is improved to $\Lambda_{\rm NSI}$=145 GeV and limits on the coupling of light new mediators are lowered down to $4 \cdot 10^{-7}$ (90% C.L.) with the new data. Finally, the determination of the Weinberg angle with CE$\nu$NS and reactor antineutrinos yields $\sin^{2}\theta_W= 0.28^{+0.03}_{-0.04}$ at a momentum transfer of $\sim 10 \ \mathrm{MeV}$.

hep-ex↗

arXiv2026

Sub-keV energy calibration of CONUS+ via 71Ge M-shell neutron activation

The CONUS+ experiment has recently reported the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) of reactor antineutrinos on germanium nuclei and is now entering a precision phase. The dominant uncertainty in the first measurement was the energy scale, which contributed 14% to the uncertainty of the prediction of the combined signal. We present a dedicated neutron activation campaign in which one of the new 2.4 kg CONUS+ germanium detectors was irradiated with a strong 241AmBe source, demonstrating that a contribution below 4% to the uncertainty of signal prediction is achievable. For the first time, the 71Ge M-shell X-ray line was clearly resolved at (158.7+-1.4) eVee, validating the CONUS+ energy reconstruction down to the detection threshold. This validation includes the understanding of the energy scale, the energy resolution, the trigger efficiency, and the correct separation of physical from noise events. These results establish the foundation for a future activation campaign at the Kernkraftwerk Leibstadt reactor site, strengthening the CONUS+ energy calibration and extending its sensitivity to precision CEvNS and beyond Standard Model physics measurements.

hep-ex↗