Inverse Beta Decay Interactions Research Articles

Search for a Sub-eV Sterile Neutrino Using Daya Bay's Full Dataset.

This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158days of detector operation, which contains 5.55×10^{6} reactor ν[over ¯]_{e} candidates identified as inverse beta-decay interactions followed by neutron capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties. No significant oscillation due to mixing of a sub-eV sterile neutrino with active neutrinos was found. Exclusion limits are set by both Feldman-Cousins and CLs methods. Light sterile neutrino mixing with sin^{2}2θ_{14}≳0.01 can be excluded at 95% confidence level in the region of 0.01 eV^{2}≲|Δm_{41}^{2}|≲0.1 eV^{2}. This result represents the world-leading constraints in the region of 2×10^{-4} eV^{2}≲|Δm_{41}^{2}|≲0.2 eV^{2}.

Real-time monitoring for the next core-collapse supernova in JUNO

The core-collapse supernova (CCSN) is considered one of the most energetic astrophysical events in the universe. The early and prompt detection of neutrinos before (pre-SN) and during the supernova (SN) burst presents a unique opportunity for multi-messenger observations of CCSN events. In this study, we describe the monitoring concept and present the sensitivity of the system to pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton liquid scintillator detector currently under construction in South China.The real-time monitoring system is designed to ensure both prompt alert speed and comprehensive coverage of progenitor stars. It incorporates prompt monitors on the electronic board as well as online monitors at the data acquisition stage.Assuming a false alert rate of 1 per year, this monitoring system exhibits sensitivity to pre-SN neutrinos up to a distance of approximately 1.6 (0.9) kiloparsecs and SN neutrinos up to about 370 (360) kiloparsecs for a progenitor mass of 30 solar masses, considering both normal and inverted mass ordering scenarios.The pointing ability of the CCSN is evaluated by analyzing the accumulated event anisotropy of inverse beta decay interactions from pre-SN or SN neutrinos. This, along with the early alert, can play a crucial role in facilitating follow-up multi-messenger observations of the next galactic or nearby extragalactic CCSN.

Geo- and reactor antineutrino sensitivity at THEIA

We present the sensitivity of the Theia experiment to low-energy geo- and reactor antineutrinos. For this study, we consider one of the possible proposed designs, a 17.8-ktonne fiducial volume Theia-25 detector filled with water-based liquid scintillator placed at Sanford Underground Research Facility (SURF). We demonstrate Theia’s sensitivity to measure the geo- and reactor antineutrinos via inverse-beta decay interactions after one year of data taking with 11.9 times 10^{32} free target protons. Considering all uncertainties on input throughout the whole analysis chain, the expected number of geo- and reactor antineutrinos is 220,^{+30}_{-24} (stats+syst) and 168,^{+26}_{-24} (stat+sys), respectively, after one year of data taking. The corresponding expected fit precision of a sole experiment is evaluated at 8.7% and 10.1%, respectively. We also demonstrate the sensitivity towards fitting individual Th and U contributions, with best fit values of N_text {Th}=40^{+26}_{-22} (stat+sys) and N_text {U}=180^{+30}_{-24} (stat+sys). Finally, from the fit results of individual Th and U contributions, we evaluate the mantle signal to be S_text {mantle} = 9.3,pm [5.2,5.4] NIU (stat+sys). This was obtained assuming a full-range positive correlation (rho _cin [0, 1]) between Th and U, and the projected uncertainties on the crust contributions of 8.3% (Th) and 7.0% (U).

Observing Supernova Neutrino Light Curves with Super-Kamiokande. III. Extraction of Mass and Radius of Neutron Stars from Synthetic Data

Neutrinos are guaranteed to be observable from the next Galactic supernova (SN). Optical light and gravitational waves are also observable, but may be difficult to observe if the location of the SN in the Galaxy or the details of the explosion are unsuitable. The key to observing the next SN is to first use neutrinos to understand various physical quantities and then link them to other signals. In this paper, we present Monte Carlo sampling calculations of neutrino events from Galactic SN explosions observed with Super-Kamiokande. The analytical solution of neutrino emission, which represents the long-term evolution of the neutrino light curve from SNe, is used as a theoretical template. It gives the event rate and event spectrum through inverse beta decay interactions with explicit model parameter dependence. Parameter estimation is performed on these simulated sample data by fitting least squares using the analytical solution. The results show that the mass, radius, and total energy of a remnant neutron star produced by an SN can be determined with an accuracy of ∼ 0.1 M ⊙, ∼1 km, and ∼ 1051 erg, respectively, for a Galactic SN at 8 kpc.

Supernova neutrino detection in NOvA

The NOvA long-baseline neutrino experiment uses a pair of large, segmented, liquid-scintillator calorimeters to study neutrino oscillations, using GeV-scale neutrinos from the Fermilab NuMI beam. These detectors are also sensitive to the flux of neutrinos which are emitted during a core-collapse supernova through inverse beta decay interactions on carbon at energies of \U0001d4aa(10 MeV). This signature provides a means to study the dominant mode of energy release for a core-collapse supernova occurring in our galaxy. We describe the data-driven software trigger system developed and employed by the NOvA experiment to identify and record neutrino data from nearby galactic supernovae. This technique has been used by NOvA to self-trigger on potential core-collapse supernovae in our galaxy, with an estimated sensitivity reaching out to 10 kpc distance while achieving a detection efficiency of 23% to 49% for supernovae from progenitor stars with masses of 9.6 M⊙ to 27 M⊙, respectively.

Supernova neutrino detection in XENONnT neutron and muon Vetoes

The current phase of the XENON Dark Matter Project, named XENONnT, will be operative in 2020 in the underground Laboratori Nazionali del Gran Sasso (LNGS). It is a multi-ton detector for direct search of Dark Matter, consisting of a double phase liquid-gas xenon Time Projection Chamber (TPC) which contains 5.9 tons of liquid xenon target mass, inserted in a cryostat surrounded by a tank containing 700 tons of water doped with Gd sulphate. Its aim, as that of its precursor XENON1T, is to detect elastic scattering of Weakly Interacting Massive Particles (WIMPs) off xenon nuclei. The presence of two Veto sub-systems, the muon Veto instrumented with 84 photomultiplier tubes (PMTs) and the neutron Veto with other 120 PMTs, allows to reduce the background for WIMPs search through muon and neutron tagging, while the presence of Gd sulphate increases the neutron capture cross section. Thanks to the large xenon target used and the presence of the two Vetoes, XENONnT will be able also to detect all flavours of Supernova neutrinos. Here the results from Monte Carlo simulations of XENONnT detection efficiency are presented for Supernova neutrinos through their inverse beta decay interactions in water of the two Veto sub-systems.

Core-Collapse Supernova neutrino detection with KM3NeT

Core Collapse Supernovae (CCSNe) are explosive phenomena that may occur at the end of the life of massive stars, releasing over 99% of the energy through neutrino emission. While the explosion mechanism is not fully understood, neutrinos are believed to play an important role. The only detection as of today are the 24 neutrinos from SN1987A. The observation of the next Galactic CCSN will lead to important breakthroughs in astroparticle physics. For a Galactic CCSN, the KM3NeT ORCA and ARCA detectors in the Mediterranean Sea will observe a significant neutrino signal via the detection of Cherenkov light, mostly induced by Inverse Beta Decay interactions in sea water. The detection of coincident photons by the 31 photomultipliers of each KM3NeT digital optical module (DOM) allows for an efficient discrimination of the optical backgrounds. The KM3NeT detection sensitivity to a Galactic CCSN and the potential to resolve the neutrino light-curve have been estimated relying on detailed Monte Carlo simulations. Specific criteria are proposed for the online triggering and the participation in the SNEWS network.

Measurement of electron antineutrino oscillation based on 1230 days of operation of the Daya Bay experiment

A measurement of electron antineutrino oscillation by the Daya Bay Reactor Neutrino Experiment is described in detail. Six 2.9-GW$_{\rm th}$ nuclear power reactors of the Daya Bay and Ling Ao nuclear power facilities served as intense sources of $\overline{\nu}_{e}$'s. Comparison of the $\overline{\nu}_{e}$ rate and energy spectrum measured by antineutrino detectors far from the nuclear reactors ($\sim$1500-1950 m) relative to detectors near the reactors ($\sim$350-600 m) allowed a precise measurement of $\overline{\nu}_{e}$ disappearance. More than 2.5 million $\overline{\nu}_{e}$ inverse beta decay interactions were observed, based on the combination of 217 days of operation of six antineutrino detectors (Dec. 2011--Jul. 2012) with a subsequent 1013 days using the complete configuration of eight detectors (Oct. 2012--Jul. 2015). The $\overline{\nu}_{e}$ rate observed at the far detectors relative to the near detectors showed a significant deficit, $R=0.949 \pm 0.002(\mathrm{stat.}) \pm 0.002(\mathrm{syst.})$. The energy dependence of $\overline{\nu}_{e}$ disappearance showed the distinct variation predicted by neutrino oscillation. Analysis using an approximation for the three-flavor oscillation probability yielded the flavor-mixing angle $\sin^22\theta_{13}=0.0841 \pm 0.0027(\mathrm{stat.}) \pm 0.0019(\mathrm{syst.})$ and the effective neutrino mass-squared difference of $\left|{\Delta}m^2_{\mathrm{ee}}\right|=(2.50 \pm 0.06(\mathrm{stat.}) \pm 0.06(\mathrm{syst.})) \times 10^{-3}\ {\rm eV}^2$. Analysis using the exact three-flavor probability found ${\Delta}m^2_{32}=(2.45 \pm 0.06(\mathrm{stat.}) \pm 0.06(\mathrm{syst.})) \times 10^{-3}\ {\rm eV}^2$ assuming the normal neutrino mass hierarchy and ${\Delta}m^2_{32}=(-2.56 \pm 0.06(\mathrm{stat.}) \pm 0.06(\mathrm{syst.})) \times 10^{-3}\ {\rm eV}^2$ for the inverted hierarchy.

Reconstructing the direction of reactor antineutrinos via electron scattering in Gd-doped water Cherenkov detectors

The potential of elastic antineutrino-electron scattering in a Gd-doped water Cherenkov detector to determine the direction of a nuclear reactor antineutrino flux was investigated using the recently proposed WATCHMAN antineutrino experiment as a baseline model. The expected scattering rate was determined assuming a 13-km standoff from a 3.758-GWt light water nuclear reactor and the detector response was modeled using a Geant4-based simulation package. Background was estimated via independent simulations and by scaling published measurements from similar detectors. Background contributions were estimated for solar neutrinos, misidentified reactor-based inverse beta decay interactions, cosmogenic radionuclides, water-borne radon, and gamma rays from the photomultiplier tubes (PMTs), detector walls, and surrounding rock. We show that with the use of low background PMTs and sufficient fiducialization, water-borne radon and cosmogenic radionuclides pose the largest threats to sensitivity. Directional sensitivity was then analyzed as a function of radon contamination, detector depth, and detector size. The results provide a list of experimental conditions that, if satisfied in practice, would enable antineutrino directional reconstruction at 3σ significance in large Gd-doped water Cherenkov detectors with greater than 10-km standoff from a nuclear reactor.

Readout electronics validation and target detector assessment for the Neutrinos Angra experiment

A compact surface detector designed to identify the inverse beta decay interaction produced by anti-neutrinos coming from near operating nuclear reactors is being developed by the Neutrinos Angra Collaboration. In this document we describe and test the detector and its readout system by means of cosmic rays acquisition. In this measurement campaign, the target detector has been equipped with 16 8-in PMTs and two scintillator paddles have been used to trigger cosmic ray events. The achieved results disclosed the main operational characteristics of the Neutrinos Angra system and have been used to assess the detector and to validate its readout system.

Monitoring nuclear reactors for safeguards purposes using anti-neutrinos

Preventing nuclear proliferation is a high priority for the international community. Monitoring of nuclear facilities to detect unauthorised removal of fissile materials from operational cores is central to this. Neutrino detection devices can be used to remotely monitor the core of operating reactors in a safe, reliable manner. Technology developed for the T2K experiment can be adapted to make a small footprint, reliable, anti-neutrino detector. Through, characterisation of the anti-neutrino spectrum there is a possibility to provide core material accountancy.A prototype of such a device has been developed and demonstrated at the University of Liverpool. Based on the design of the T2K Near Detector Calorimeter, the device will detect anti-neutrinos through the distinctive delayed coincidence signal of inverse beta decay interactions. This poster presented data from detector commissioning. The detector is currently deployed at Wylfa power station, UK for field testing.

Spectral structure of electron antineutrinos from nuclear reactors.

Recent measurements of the positron energy spectrum obtained from inverse beta decay interactions of reactor electron antineutrinos show an excess in the 4 to 6MeV region relative to current predictions. First-principles calculations of fission and beta decay processes within a typical pressurized water reactor core identify prominent fission daughter isotopes as a possible origin for this excess. These calculations also predict percent-level substructures in the antineutrino spectrum due to Coulomb effects in beta decay. Precise measurement of these substructures can elucidate the nuclear processes occurring within reactors. These substructures can be a systematic issue for measurements utilizing the detailed spectral shape.

Status of the Super-Kamiokande gadolinium project

The diffuse flux of neutrinos released from all past supernova explosions in the universe is known as the supernova relic neutrinos (SRN). Super-Kamiokande (SK) has conducted searches for these SRN events via their inverse beta decay interactions in the detector, in the process establishing the world's best limits on this still unobserved flux. These limits are within about a factor of two of the theoretically predicted fluxes. But these searches are background limited, and without some major improvement further progress will be difficult. The addition of gadolinium (Gd) compound into the SK detector was proposed to reduce background. Gd has the largest thermal neutron capture cross-section among all stable nuclei and emits an 8MeV γ cascade following the capture. By coincidental tagging of positrons with the γ rays from Gd neutron capture, we can identify the dominant SRN signal in SK: inverse beta decay. This Gd-loading technique should allow SK to make the world's first observation of a SRN signal. We will demonstrate the principle of a Gd-doped water Cherenkov detector (transparency of the Gd-doped water, Gd-doped water circulation method, neutron capture efficiency, etc) with a dedicated test facility named EGADS. EGADS consists of a 200ton water Cherenkov detector, a Gd dissolving pre-treatment device, a Gd-capable water circulation system, and a custom-built water transparency measurement device. We have evaluated Gd-doped water circulation using the main EGADS water system since 2012. The evaluation of the overall performance of EGADS will start in 2013 after PMT installation.

First measurement of [formula omitted] from delayed neutron capture on hydrogen in the Double Chooz experiment

The Double Chooz experiment has determined the value of the neutrino oscillation parameter θ13 from an analysis of inverse beta decay interactions with neutron capture on hydrogen. This analysis uses a three times larger fiducial volume than the standard Double Chooz assessment, which is restricted to a region doped with gadolinium (Gd), yielding an exposure of 113.1 GW-ton-years. The data sample used in this analysis is distinct from that of the Gd analysis, and the systematic uncertainties are also largely independent, with some exceptions, such as the reactor neutrino flux prediction. A combined rate- and energy-dependent fit finds sin22θ13=0.097±0.034 (stat.)±0.034 (syst.), excluding the no-oscillation hypothesis at 2.0σ. This result is consistent with previous measurements of sin22θ13.

Proposal for an Electron Antineutrino Disappearance Search Using High-RateLi8Production and Decay

This paper introduces an experimental probe of the sterile neutrino with a novel, high-intensity source of electron antineutrinos from the production and subsequent decay of 8Li. When paired with an existing ∼1 kton scintillator-based detector, this <E(ν)> = 6.4 MeV source opens a wide range of possible searches for beyond standard model physics via studies of the inverse beta decay interaction ν(e) + p → e+ + n. In particular, the experimental design described here has unprecedented sensitivity to ν(e) disappearance at Δm2 ∼ 1 eV2 and features the ability to distinguish between the existence of zero, one, and two sterile neutrinos.

Detecting the Neutrino

In 1930 Wolfgang Pauli suggested that a new particle might be required to make sense of the radioactive-disintegration mode known as beta decay. This conjecture initially seemed impossible to verify since the new particle, which became known as the neutrino, was uncharged, had zero or small mass, and interacted only insignificantly with other matter. In 1951 Frederick Reines and Clyde L. Cowan, Jr., of the Los Alamos Scientific Laboratory undertook the difficult task of detecting the free neutrino by observing its inverse beta-decay interaction with matter. They succeeded in 1956. The neutrino was accepted rapidly as a fundamental particle despite discrepancies in reported details of the experiments and despite the absence of independent verification of the result. This paper describes the experiments, examines the nature of the discrepancies, and discusses the circumstances of the acceptance of the neutrino's detection by the physics community.

Measurements of the 8B and 7Be νe fluxes from the sun with a Cerenkov triggered radiochemical neutrino detector

The rate of flavor transformation of solar ν e into other neutrino species can be measured by u in interaction rates in detectors that rely on neutrino-electron scattering and those that utilize the inverse beta decay interactions of ν e . We plan to measure the latter rates for both 8B and 7Be ν e from the Sun by use of an electronically triggered radiochemical detector. In this detector, a set of photomultiplier tubes detects the Cerenkov radiation generated by neutrino interaction secondaries and initiates a fast extraction of the secondary atom from the detector and directs this atom to a specific charcoal storage trap.