arXiv subjects

A. B. Balantekin

Publications and source records attributed to A. B. Balantekin.

At least 55 records · Page 3Linked to original sources

arXiv2022

Joint Determination of Reactor Antineutrino Spectra from $^{235}$U and $^{239}$Pu Fission by Daya Bay and PROSPECT

A joint determination of the reactor antineutrino spectra resulting from the fission of $^{235}$U and $^{239}$Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level of consistency of $^{235}$U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant $^{235}$U and $^{239}$Pu isotopes and improves the uncertainty of the $^{235}$U spectral shape to about 3\%. The ${}^{235}$U and $^{239}$Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the $^{235}$U and $^{239}$Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.

nucl-ex↗

arXiv2021

Spectral splits and entanglement entropy in collective neutrino oscillations

In environments such as core-collapse supernovae, neutron star mergers, or the early universe, where the neutrino fluxes can be extremely high, neutrino-neutrino interactions are appreciable and contribute substantially to their flavor evolution. Such a system of interacting neutrinos can be regarded as a quantum many-body system, and prospects for nontrivial quantum correlations, i.e., entanglement, developing in a gas of interacting neutrinos have been investigated previously. In this work, we uncover an intriguing connection between the entropy of entanglement of individual neutrinos with the rest of the ensemble, and the occurrence of spectral splits in the energy spectra of these neutrinos, which develop as a result of collective neutrino oscillations. In particular, for various types of neutrino spectra, we demonstrate that the entanglement entropy is highest for the neutrinos whose locations in the energy spectrum are closest to the spectral split(s). This trend demonstrates that the quantum entanglement is strongest among the neutrinos that are close to these splits, a behavior that seems to persist even as the size of the many-body system is increased.

hep-ph↗

arXiv2021

Lipkin model on a quantum computer

Atomic nuclei are important laboratories for exploring and testing new insights into the universe, such as experiments to directly detect dark matter or explore properties of neutrinos. The targets of interest are often heavy, complex nuclei that challenge our ability to reliably model them (as well as quantify the uncertainty of those models) with classical computers. Hence there is great interest in applying quantum computation to nuclear structure for these applications. As an early step in this direction, especially with regards to the uncertainties in the relevant quantum calculations, we develop circuits to implement variational quantum eigensolver (VQE) algorithms for the Lipkin-Meshkov-Glick model, which is often used in the nuclear physics community as a testbed for many-body methods. We present quantum circuits for VQE for two and three particles and discuss the construction of circuits for more particles. Implementing the VQE for a two-particle system on the IBM Quantum Experience, we identify initialization and two-qubit gates as the largest sources of error. We find that error mitigation procedures reduce the errors in the results significantly, but additional quantum hardware improvements are needed for quantum calculations to be sufficiently accurate to be competitive with the best current classical methods.

hep-th↗

arXiv2021

Limits on Sub-GeV Dark Matter from the PROSPECT Reactor Antineutrino Experiment

If dark matter has mass lower than around 1 GeV, it will not impart enough energy to cause detectable nuclear recoils in many direct-detection experiments. However, if dark matter is upscattered to high energy by collisions with cosmic rays, it may be detectable in both direct-detection experiments and neutrino experiments. We report the results of a dedicated search for boosted dark matter upscattered by cosmic rays using the PROSPECT reactor antineutrino experiment. We show that such a flux of upscattered dark matter would display characteristic diurnal sidereal modulation, and use this to set new experimental constraints on sub-GeV dark matter exhibiting large interaction cross-sections.

hep-ex↗

arXiv2021

Joint Measurement of the $^{235}$U Antineutrino Spectrum by Prospect and Stereo

The PROSPECT and STEREO collaborations present a combined measurement of the pure $^{235}$U antineutrino spectrum, without site specific corrections or detector-dependent effects. The spectral measurements of the two highest precision experiments at research reactors are found to be compatible with $χ^2/\mathrm{ndf} = 24.1/21$, allowing a joint unfolding of the prompt energy measurements into antineutrino energy. This $\barν_e$ energy spectrum is provided to the community, and an excess of events relative to the Huber model is found in the 5-6 MeV region. When a Gaussian bump is fitted to the excess, the data-model $χ^2$ value is improved, corresponding to a $2.4σ$ significance.

nucl-ex↗

arXiv2021

Antineutrino Energy Spectrum Unfolding Based on the Daya Bay Measurement and Its Applications

The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era. The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment, in combination with the fission rates of fissile isotopes in the reactor, is used to extract the positron energy spectra resulting from the fission of specific isotopes. This information can be used to produce a precise, data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay. The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method. Consistent results are obtained with other unfolding methods. A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated. Given the reactor fission fractions, the technique can predict the energy spectrum to a 2% precision. In addition, we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.

hep-ex↗

arXiv2020

Search For Electron-Antineutrinos Associated With Gravitational-Wave Events GW150914, GW151012, GW151226, GW170104, GW170608, GW170814, and GW170817 at Daya Bay

Providing a possible connection between neutrino emission and gravitational-wave (GW) bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge. In the Daya Bay experiment, using data collected from December 2011 to August 2017, a search has been performed for electron-antineutrino signals coinciding with detected GW events, including GW150914, GW151012, GW151226, GW170104, GW170608, GW170814, and GW170817. We used three time windows of $\mathrm{\pm 10~s}$, $\mathrm{\pm 500~s}$, and $\mathrm{\pm 1000~s}$ relative to the occurrence of the GW events, and a neutrino energy range of 1.8 to 100 MeV to search for correlated neutrino candidates. The detected electron-antineutrino candidates are consistent with the expected background rates for all the three time windows. Assuming monochromatic spectra, we found upper limits (90% confidence level) on electron-antineutrino fluence of $(1.13~-~2.44) \times 10^{11}~\rm{cm^{-2}}$ at 5 MeV to $8.0 \times 10^{7}~\rm{cm^{-2}}$ at 100 MeV for the three time windows. Under the assumption of a Fermi-Dirac spectrum, the upper limits were found to be $(5.4~-~7.0)\times 10^{9}~\rm{cm^{-2}}$ for the three time windows.

astro-ph.HE↗

arXiv2020

Optimization of the JUNO liquid scintillator composition using a Daya Bay antineutrino detector

To maximize the light yield of the liquid scintillator (LS) for the Jiangmen Underground Neutrino Observatory (JUNO), a 20 t LS sample was produced in a pilot plant at Daya Bay. The optical properties of the new LS in various compositions were studied by replacing the gadolinium-loaded LS in one antineutrino detector. The concentrations of the fluor, PPO, and the wavelength shifter, bis-MSB, were increased in 12 steps from 0.5 g/L and <0.01 mg/L to 4 g/L and 13 mg/L, respectively. The numbers of total detected photoelectrons suggest that, with the optically purified solvent, the bis-MSB concentration does not need to be more than 4 mg/L. To bridge the one order of magnitude in the detector size difference between Daya Bay and JUNO, the Daya Bay data were used to tune the parameters of a newly developed optical model. Then, the model and tuned parameters were used in the JUNO simulation. This enabled to determine the optimal composition for the JUNO LS: purified solvent LAB with 2.5 g/L PPO, and 1 to 4 mg/L bis-MSB.

physics.ins-det↗

arXiv2020

Improved Short-Baseline Neutrino Oscillation Search and Energy Spectrum Measurement with the PROSPECT Experiment at HFIR

We present a detailed report on sterile neutrino oscillation and U-235 antineutrino energy spectrum measurement results from the PROSPECT experiment at the highly enriched High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. In 96 calendar days of data taken at an average baseline distance of 7.9 m from the center of the 85 MW HFIR core, the PROSPECT detector has observed more than 50,000 interactions of antineutrinos produced in beta decays of U-235 fission products. New limits on the oscillation of antineutrinos to light sterile neutrinos have been set by comparing the detected energy spectra of ten reactor-detector baselines between 6.7 and 9.2 meters. Measured differences in energy spectra between baselines show no statistically significant indication of antineutrinos to sterile neutrino oscillation and disfavor the Reactor Antineutrino Anomaly best-fit point at the 2.5$σ$ confidence level. The reported U-235 antineutrino energy spectrum measurement shows excellent agreement with energy spectrum models generated via conversion of the measured U-235 beta spectrum, with a $χ^2$/DOF of 31/31. PROSPECT is able to disfavor at 2.4$σ$ confidence level the hypothesis that U-235 antineutrinos are solely responsible for spectrum discrepancies between model and data obtained at commercial reactor cores. A data-model deviation in PROSPECT similar to that observed by commercial core experiments is preferred with respect to no observed deviation, at a 2.2$σ$ confidence level.

hep-ex↗

arXiv2020

Note on arXiv:2005.05301, 'Preparation of the Neutrino-4 experiment on search for sterile neutrino and the obtained results of measurements'

We comment on the claimed observation [arXiv:arXiv:2005.05301] of sterile neutrino oscillations by the Neutrino-4 collaboration. Such a claim, which requires the existence of a new fundamental particle, demands a level of rigor commensurate with its impact. The burden lies with the Neutrino-4 collaboration to provide the information necessary to prove the validity of their claim to the community. In this note, we describe aspects of both the data and analysis method that might lead to an oscillation signature arising from a null experiment and describe additional information needed from the Neutrino-4 collaboration to support the oscillation claim. Additionally, as opposed to the assertion made by the Neutrino-4 collaboration, we also show that the method of 'coherent summation' using the $L/E$ parameter produces similar results to the methods used by the PROSPECT and the STEREO collaborations.

hep-ex↗

arXiv2020

Nonfuel Antineutrino Contributions in the High Flux Isotope Reactor

Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of $\overlineν_{e}$ is important when making theoretical predictions. One source of $\overlineν_{e}$ that is often neglected arises from the irradiation of the nonfuel materials in reactors. The $\overlineν_{e}$ rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible $\overlineν_{e}$ sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the $\overlineν_{e}$ source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel $\overlineν_{e}$ contributions from HFIR to PROSPECT amount to 1\% above the inverse beta decay threshold with a maximum contribution of 9\% in the 1.8--2.0~MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel $\overlineν_{e}$ contribution.

nucl-ex↗

arXiv2020

Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments

Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the $θ_{μe}$ mixing angle are derived that constitute the most stringent limits to date over five orders of magnitude in the sterile mass-squared splitting $Δm^2_{41}$, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL$_s$ for $Δm^2_{41}<5\,$eV$^2$.Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL$_s$ for $Δm^2_{41}$ $<$ 1.2 eV$^2$.

hep-ex↗

arXiv2019

Proceedings of The Magnificent CE$ν$NS Workshop 2018

The Magnificent CE$ν$NS Workshop (2018) was held November 2 & 3 of 2018 on the University of Chicago campus and brought together theorists, phenomenologists, and experimentalists working in numerous areas but sharing a common interest in the process of coherent elastic neutrino-nucleus scattering (CE$ν$NS). This is a collection of abstract-like summaries of the talks given at the meeting, including links to the slides presented. This document and the slides from the meeting provide an overview of the field and a snapshot of the robust CE$ν$NS-related efforts both planned and underway.

hep-ex↗

arXiv2019

Entanglement and collective flavor oscillations in a dense neutrino gas

We investigate the importance of going beyond the mean-field approximation in the dynamics of collective neutrino oscillations. To expand our understanding of the coherent neutrino oscillation problem, we apply concepts from many-body physics and quantum information theory. Specifically, we use measures of nontrivial correlations (otherwise known as "entanglement") between the constituent neutrinos of the many-body system, such as the entanglement entropy and the Bloch vector of the reduced density matrix. The relevance of going beyond the mean field is demonstrated by comparisons between the evolution of the neutrino state in the many-body picture vs the mean-field limit, for different initial conditions.

hep-ph↗

arXiv2019

Extraction of the $^{235}$U and $^{239}$Pu Antineutrino Spectra at Daya Bay

This Letter reports the first extraction of individual antineutrino spectra from $^{235}$U and $^{239}$Pu fission and an improved measurement of the prompt energy spectrum of reactor antineutrinos at Daya Bay. The analysis uses $3.5\times 10^6$ inverse beta-decay candidates in four near antineutrino detectors in 1958 days. The individual antineutrino spectra of the two dominant isotopes, $^{235}$U and $^{239}$Pu, are extracted using the evolution of the prompt spectrum as a function of the isotope fission fractions. In the energy window of 4--6~MeV, a 7\% (9\%) excess of events is observed for the $^{235}$U ($^{239}$Pu) spectrum compared with the normalized Huber-Mueller model prediction. The significance of discrepancy is $4.0σ$ for $^{235}$U spectral shape compared with the Huber-Mueller model prediction. The shape of the measured inverse beta-decay prompt energy spectrum disagrees with the prediction of the Huber-Mueller model at $5.3σ$. In the energy range of 4--6~MeV, a maximal local discrepancy of $6.3σ$ is observed.

hep-ex↗

arXiv2019

The PROSPECT Reactor Antineutrino Experiment

The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make both a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and to probe eV-scale sterile neutrinos by searching for neutrino oscillations over meter-long baselines. PROSPECT utilizes a segmented $^6$Li-doped liquid scintillator detector for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT is a movable 4-ton antineutrino detector covering distances of 7m to 13m from the High Flux Isotope Reactor core. It will probe the best-fit point of the $\barν_e$ disappearance experiments at 4$σ$ in 1 year and the favored regions of the sterile neutrino parameter space at more than 3$σ$ in 3 years. PROSPECT will test the origin of spectral deviations observed in recent $θ_{13}$ experiments, search for sterile neutrinos, and address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly. This paper describes the design, construction, and commissioning of PROSPECT and reports first data characterizing the performance of the PROSPECT antineutrino detector.

physics.ins-det↗

arXiv2019

The Radioactive Source Calibration System of the PROSPECT Reactor Antineutrino Detector

The Precision Reactor Oscillation and Spectrum (PROSPECT) Experiment is a reactor neutrino experiment designed to search for sterile neutrinos with a mass on the order of 1 eV/c$^2$ and to measure the spectrum of electron antineutrinos from a highly-enriched $^{235}$U nuclear reactor. The PROSPECT detector consists of an 11 by 14 array of optical segments in $^{6}$Li-loaded liquid scintillator at the High Flux Isotope Reactor in Oak Ridge National Laboratory. Antineutrino events are identified via inverse beta decay and read out by photomultiplier tubes located at the ends of each segment. The detector response is characterized using a radioactive source calibration system. This paper describes the design, operation, and performance of the PROSPECT source calibration system.

physics.ins-det↗

arXiv2019

A high precision calibration of the nonlinear energy response at Daya Bay

A high precision calibration of the nonlinearity in the energy response of the Daya Bay Reactor Neutrino Experiment's antineutrino detectors is presented in detail. The energy nonlinearity originates from the particle-dependent light yield of the scintillator and charge-dependent electronics response. The nonlinearity model is constrained by $γ$ calibration points from deployed and naturally occurring radioactive sources, the $β$ spectrum from $^{12}$B decays, and a direct measurement of the electronics nonlinearity with a new flash analog-to-digital converter readout system. Less than 0.5% uncertainty in the energy nonlinearity calibration is achieved for positrons of kinetic energies greater than 1 MeV.

physics.ins-det↗