arXiv subjects

O. I. González-Reina

Publications and source records attributed to O. I. González-Reina.

9 recordsLinked to original sources

arXiv2025

First Evidence of Solar Neutrino Interactions on $^{13}$C

The SNO+ Collaboration reports the first evidence of $^{8}\text{B}$ solar neutrinos interacting on $^{13}\text{C}$ nuclei. The charged current interaction proceeds through $^{13}\text{C} + ν_e \rightarrow {}^{13}\text{N} + e^-$ which is followed, with a 10 minute half-life, by ${}^{13}\text{N} \rightarrow {}^{13}\text{C} + e^+ +ν_e .$ The detection strategy is based on the delayed coincidence between the electron and the positron. Evidence for the charged current signal is presented with a significance of 4.2$σ$. Using the natural abundance of $^{13}\text{C}$ present in the scintillator, 5.7 tonnes of $^{13}\text{C}$ over 231 days of data were used in this analysis. The 5.6$^{+3.0}_{-2.3}$ observed events in the data set are consistent with the expectation of 4.7$^{+0.6}_{-1.3}$ events. This result is the second real-time measurement of CC interactions of $^{8}\text{B}$ neutrinos with nuclei and constitutes the lowest energy observation of neutrino interactions on $^{13}\text{C}$ generally. This enables the first direct measurement of the CC $ν_e$ reaction to the ground state of ${}^{13}\text{N}$, yielding an average cross section of $(16.1 ^{+8.5}_{-6.7} (\text{stat.}) ^{+1.6}_{-2.7} (\text{syst.}) )\times 10^{-43}$ cm$^{2}$ over the relevant $^{8}\text{B}$ solar neutrino energies.

nucl-ex↗

arXiv2025

Measurement of reactor antineutrino oscillation at SNO+

The SNO+ collaboration reports its second spectral analysis of reactor antineutrino oscillation using 286 tonne-years of new data. The measured energies of reactor antineutrino candidates were fitted to obtain the second-most precise determination of the neutrino mass-squared difference $Δm^2_{21}$ = ($7.96^{+0.48}_{-0.42}$) $\times$ 10$^{-5}$ eV$^2$. Constraining $Δm^2_{21}$ and $\sin^2θ_{12}$ with measurements from long-baseline reactor antineutrino and solar neutrino experiments yields $Δm^2_{21}$ = ($7.58^{+0.18}_{-0.17}$) $\times$ 10$^{-5}$ eV$^2$ and $\sin^2θ_{12} = 0.308 \pm 0.013$. This fit also yields a first measurement of the flux of geoneutrinos in the Western Hemisphere, with $73^{+47}_{-43}$ TNU at SNO+.

hep-ex↗

arXiv2025

Initial measurement of reactor antineutrino oscillation at SNO+

The SNO+ collaboration reports its first spectral analysis of long-baseline reactor antineutrino oscillation using 114 tonne-years of data. Fitting the neutrino oscillation probability to the observed energy spectrum yields constraints on the neutrino mass-squared difference $Δm^2_{21}$. In the ranges allowed by previous measurements, the best-fit $Δm^2_{21}$ is (8.85$^{+1.10}_{-1.33}$) $\times$ 10$^{-5}$ eV$^2$. This measurement is continuing in the next phases of SNO+ and is expected to surpass the present global precision on $Δm^2_{21}$ with about three years of data.

hep-ex↗

arXiv2024

Measurement of the $^8$B Solar Neutrino Flux Using the Full SNO+ Water Phase Dataset

The SNO+ detector operated initially as a water Cherenkov detector. The implementation of a sealed covergas system midway through water data taking resulted in a significant reduction in the activity of $^{222}$Rn daughters in the detector and allowed the lowest background to the solar electron scattering signal above 5 MeV achieved to date. This paper reports an updated SNO+ water phase $^8$B solar neutrino analysis with a total livetime of 282.4 days and an analysis threshold of 3.5 MeV. The $^8$B solar neutrino flux is found to be $\left(2.32^{+0.18}_{-0.17}\text{(stat.)}^{+0.07}_{-0.05}\text{(syst.)}\right)\times10^{6}$ cm$^{-2}$s$^{-1}$ assuming no neutrino oscillations, or $\left(5.36^{+0.41}_{-0.39}\text{(stat.)}^{+0.17}_{-0.16}\text{(syst.)} \right)\times10^{6}$ cm$^{-2}$s$^{-1}$ assuming standard neutrino oscillation parameters, in good agreement with both previous measurements and Standard Solar Model Calculations. The electron recoil spectrum is presented above 3.5 MeV.

hep-ex↗

arXiv2022

Improved search for invisible modes of nucleon decay in water with the SNO+ detector

This paper reports results from a search for single and multi-nucleon disappearance from the $^{16}$O nucleus in water within the \snoplus{} detector using all of the available data. These so-called "invisible" decays do not directly deposit energy within the detector but are instead detected through their subsequent nuclear de-excitation and gamma-ray emission. New limits are given for the partial lifetimes: $τ(n\rightarrow inv) > 9.0\times10^{29}$ years, $τ(p\rightarrow inv) > 9.6\times10^{29}$ years, $τ(nn\rightarrow inv) > 1.5\times10^{28}$ years, $τ(np\rightarrow inv) > 6.0\times10^{28}$ years, and $τ(pp\rightarrow inv) > 1.1\times10^{29}$ years at 90\% Bayesian credibility level (with a prior uniform in rate). All but the ($nn\rightarrow inv$) results improve on existing limits by a factor of about 3.

hep-ex↗

arXiv2022

EstrellaNueva: an open-source software to study the interactions and detection of neutrinos emitted by supernovae

Supernovae emit large fluxes of neutrinos which can be detected by detectors on Earth. Future tonne-scale detectors will be sensitive to several neutrino interaction channels, with thousands of events expected if a supernova emerges in the galaxy neighborhood. There is a limited number of tools to study the interaction rates of supernova neutrinos, although a plethora of available supernova models exists. EstrellaNueva is an open-source software to calculate expected rates of supernova neutrinos in detectors using target materials with typical compositions, and additional compositions can be easily added. This software considers the flavor transformation of neutrinos in the supernova through the adiabatic Mikheyev--Smirnov--Wolfenstein effect, and their interaction in detectors through several channels. Most of the interaction cross sections have been analytically implemented, such as neutrino-electron and neutrino-proton elastic scattering, inverse beta decay, and coherent elastic neutrino-nucleus scattering. This software provides a link between supernova simulations and the expected events in detectors by calculating fluences and event rates to ease any comparison between theory and observation. It provides a simple and standalone tool to explore many physics scenarios offering an option to add analytical cross sections and define any target material.

astro-ph.IM↗

arXiv2021

Optical calibration of the SNO+ detector in the water phase with deployed sources

SNO+ is a large-scale liquid scintillator experiment with the primary goal of searching for neutrinoless double beta decay, and is located approximately 2 km underground in SNOLAB, Sudbury, Canada. The detector acquired data for two years as a pure water Cherenkov detector, starting in May 2017. During this period, the optical properties of the detector were measured in situ using a deployed light diffusing sphere, with the goal of improving the detector model and the energy response systematic uncertainties. The measured parameters included the water attenuation coefficients, effective attenuation coefficients for the acrylic vessel, and the angular response of the photomultiplier tubes and their surrounding light concentrators, all across different wavelengths. The calibrated detector model was validated using a deployed tagged gamma source, which showed a 0.6% variation in energy scale across the primary target volume.

physics.ins-det↗

arXiv2021

The SNO+ Experiment

The SNO+ experiment is located 2 km underground at SNOLAB in Sudbury, Canada. A low background search for neutrinoless double beta ($0νββ$) decay will be conducted using 780 tonnes of liquid scintillator loaded with 3.9 tonnes of natural tellurium, corresponding to 1.3 tonnes of $^{130}$Te. This paper provides a general overview of the SNO+ experiment, including detector design, construction of process plants, commissioning efforts, electronics upgrades, data acquisition systems, and calibration techniques. The SNO+ collaboration is reusing the acrylic vessel, PMT array, and electronics of the SNO detector, having made a number of experimental upgrades and essential adaptations for use with the liquid scintillator. With low backgrounds and a low energy threshold, the SNO+ collaboration will also pursue a rich physics program beyond the search for $0νββ$ decay, including studies of geo- and reactor antineutrinos, supernova and solar neutrinos, and exotic physics such as the search for invisible nucleon decay. The SNO+ approach to the search for $0νββ$ decay is scalable: a future phase with high $^{130}$Te-loading is envisioned to probe an effective Majorana mass in the inverted mass ordering region.

physics.ins-det↗

arXiv2021

Development, characterisation, and deployment of the SNO+ liquid scintillator

A liquid scintillator consisting of linear alkylbenzene as the solvent and 2,5-diphenyloxazole as the fluor was developed for the SNO+ experiment. This mixture was chosen as it is compatible with acrylic and has a competitive light yield to pre-existing liquid scintillators while conferring other advantages including longer attenuation lengths, superior safety characteristics, chemical simplicity, ease of handling, and logistical availability. Its properties have been extensively characterized and are presented here. This liquid scintillator is now used in several neutrino physics experiments in addition to SNO+.

physics.ins-det↗