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DOE OSTI2022

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 $11.9 × 10^{32}$ 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 $S_{\text{mantle}} = 9.3±[5.2,5.4]$ NIU (stat+sys). This was obtained assuming a full-range positive correlation $(ρ_c ϵ[0,1])$ between Th and U, and the projected uncertainties on the crust contributions of 8.3% (Th) and 7.0% (U).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Pulse shape discrimination technique for diffuse supernova neutrino background search with JUNO

Pulse shape discrimination (PSD) is widely used in particle and nuclear physics. Specifically in liquid scintillator detectors, PSD facilitates the classification of different particle types based on their energy deposition patterns. This technique is particularly valuable for studies of the diffuse supernova neutrino background (DSNB), nucleon decay, and dark matter searches. This paper presents a detailed investigation of the PSD technique, applied in the DSNB search performed with the Jiangmen Underground Neutrino Observatory (JUNO). Instead of using conventional cut-and-count methods, we employ methods based on boosted decision trees and neural networks and compare their capability to distinguish the DSNB signals from the atmospheric neutrino neutral-current background events. The two methods demonstrate comparable performance, resulting in a 50–80% improvement in signal efficiency compared to a previous study performed for JUNO (An et al. [JUNO] in J Phys G 43(3):030401, 2016). Moreover, we study the dependence of the PSD performance on the visible energy and final state composition of the events and find a significant dependence on the presence/absence of 11 C. Finally, we evaluate the impact of the detector effects (photon propagation, PMT dark noise, and waveform reconstruction) on the PSD performance.

FOS: Physical sciences↗

DOE OSTI2024

Generative models for simulation of KamLAND-Zen

Abstract The next generation of searches for neutrinoless double beta decay ($$0 \nu \beta \beta $$ 0 ν β β ) are poised to answer deep questions on the nature of neutrinos and the source of the Universe’s matter–antimatter asymmetry. They will be looking for event rates of less than one event per ton of instrumented isotope per year. To claim discovery, accurate and efficient simulations of detector events that mimic$$0 \nu \beta \beta $$ 0 ν β β is critical. Traditional Monte Carlo (MC) simulations can be supplemented by machine-learning-based generative models. This work describes the performance of generative models that we designed for monolithic liquid scintillator detectors like KamLAND to produce accurate simulation data without a predefined physics model. We present their current ability to recover low-level features and perform interpolation. In the future, the results of these generative models can be used to improve event classification and background rejection by providing high-quality abundant generated data.

Physics↗

DOE OSTI2025

IsoDAR@Yemilab: Preliminary design report—volume I (cyclotron driver)

This Preliminary Design Report (PDR) describes the IsoDAR electron-antineutrino source in two volumes which are mostly site-independent and describe the cyclotron driver providing a 10 mA/60 MeV proton beam (this Volume); and the medium energy beam transport line (MEBT) and target (Volume II). The IsoDAR driver and target will produce about 1.15 x 10 23 electron-antineutrinos over 5 years while operating with the anticipated 10 mA/60 MeV beam at an estimated 80% duty factor. Paired with a kton-scale liquid scintillator detector, it will enable a broad particle physics program including searches for new symmetries, new interactions and new particles. Here in Volume I, we describe the driver, which includes the ion source, low energy beam transport, and cyclotron. The latter features Radio-Frequency Quadrupole (RFQ) direct axial injection and represents the first accelerator purpose-built to make use of so-called vortex motion.

Winklehner, Daniel (ORCID:0000000207156310)↗

DOE OSTI2020

Investigation of the Reactor Antineutrino Anomaly with CeLAND (Final Technical Report)

The goal of this project has been to investigate reactor antineutrino anomaly by searching for the oscillation signature of the hypothesized 4th neutrino flavor. The 4th neutrino flavor is often referred to as sterile, not interacting with matter and can be only observed via disappearance of standard model neutrino flavors. It is also anticipated to be heavy and therefore disappearance due to sterile neutrino oscillations is expected to happen within few meters from the neutrino source. As such, the effect can be investigated with either reactor antineutrinos few meters from the reactor core or with the dedicated strong antineutrino source close to a large liquid scintillator detector to detect antineutrinos coming from the source.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Strategic Survey of Antineutrino-based Nonproliferation Technologies

Antineutrinos carry approximately 3% of the total energy released in fission processes. As a consequence, nuclear energy production provides by far the brightest antineutrino sources on Earth. Antineutrino interactions with ordinary matter are weak and these particles cannot be shielded, making them an ideal signature of fissioning systems. However, the same property makes antineutrinos difficult to detect. Antineutrino detection technologies have matured in recent years, and emerging detection approaches warrant further investment. For near-field applications, the major enabling technological advancement, reported in 2018, is the conclusive detection of the antineutrino spectrum in segmented detectors operating at the surface with minimal shielding. For far-field applications, the highlights are the routine detection of reactor antineutrinos at hundreds of kilometer standoff in the kiloton-scale KamLAND and Borexino liquid scintillator detectors, and in particular the observation of the residual South Korean reactor antineutrino flux in KamLAND following the Fukushima disaster that led to shutdown of reactors in Japan

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2020

Data review processes in the analytical laboratory

These documents contain information on the Analytical laboratory data review processes for the following analytical techniques: - alpha spectrometry - light elements analyses - gamma spectrometry - gas proportional flow counting - HR-ICP-MS - Q-ICP-MS - MC-ICP-MS - ICP OES - liquid scintillation counting

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Steps toward FNCL Cell Replacement (FY2021 Mid-Year Annual Report)

Evaluate compact replacement cells for the Fast Neutron Collar (FNCL). The current cells are 4x4x4 in 3 of EJ-309 instrumented with 8” tall PMTs, and the replacements are 4x4x3 in 3 cells instrumented with 1” tall SiPM arrays. The replacement cell materials are stilbene (organic crystal), EJ-309 (liquid scintillator), and EJ-299-33M (PSD-capable plastic).

42 ENGINEERING↗

DOE OSTI2022

LLE Diagnostic Resource Team for Innovative Fusion Concepts (Final Report)

The LLE Diagnostic Resource Team for Innovative Fusion Concepts provided travelling neutron diagnostics, consultancy on neutron diagnostics, and consultancy on tritium handling to fusion companies. An existing neutron detector was recalibrated for low yields and two detectors were built based on designs proven on the Omega Laser Facility. The three detectors allow measurements over a wide range of yields (from 10 to 1E7 incident neutrons). The detectors were calibrated for DD neutrons on a dedicated OMEGA shot day. Neutron detectors from the company MIFTI were also calibrated on OMEGA. MIFTI is currently using their detectors and two of our detectors on staged Z-pinch experiments at UCSD. The Team acted as consultants for the development of a liquid scintillator array to detect neutrons from muon induced fusion by NK Labs. Segments of NK Labs’ detector were tested at the LLE using radioactive sources and a DD neutron generator. The Team also acted as consultants for the design of a tritium handling system for NK Labs. A new type of neutron spectrometer was designed and built, and has completed preliminary testing.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Operation of the Fast Neutron Coincidence Collar (FNCL) with a DD-Neutron Generator

For more than 30 years, the quantitative assay of the 235 U content of light water reactor fresh fuel assemblies relied on measuring coincidence neutrons from fissions induced by an Am(Li) neutron source using 3 He based detectors. The Fast Neutron Collar (FNCL) developed by the International Atomic Energy Agency (IAEA), replaces traditional 3 He proportional counters with an array of liquid scintillator detectors arranged about the fuel assembly to provide improved measurement precision and reduced sensitivity to gadolinium poison rods. The FNCL relies on Am(Li) neutron sources that are no longer commercially available. This work examines the replacement of Am(Li) sources with a commercial off the-shelf deuterium–deuterium (DD) neutron generator. In addition to mitigating supply concerns, the neutron generator offers advantages in measurement precision and potential automation of sequential passive/active neutron measurements. This report presents the initial performance results for both the integrated DD/FNCL and Am(Li)/FNCL assays of compact depleted uranium, low-enriched uranium, and highly enriched uranium standards along with an estimate of the expected performance for fresh fuel assemblies. A discussion of the design and operation of the “FNCL Analysis and Simulation Software” is also provided.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2024

Measurement of the Prompt Fission Neutron Spectrum from 800 keV to 10 MeV for 240 Pu($sf$) and for the 240 Pu($n,f$) Reaction Induced by Neutrons of Energy from 1-20 MeV

The presence of 240 Pu in nuclear fuels for reactors has resulted in high uncertainties in the results of reactor and nuclear transmutation calculations because of deficiencies in 240 Pu-related nuclear data. Specifically for the prompt fission neutron spectrum (PFNS) of 240 Pu, there is only one neutron-induced, ($n,f$), measurement at 0.85 MeV incident neutron energy and only one complete spontaneous fission, ($sf$), measurement. This limited availability of data does not sufficiently guide nuclear data evaluations of these quantities. Here we report on a measurement of both the 240 Pu($sf$) and the 240 Pu($n,f$) PFNS, both over the emitted neutron energy range of 0.79–10.0 MeV, and from incident neutron energies of 1.0–20.0 MeV for the ($n,f$) reaction. Measurements were made with a hemispherical array of liquid scintillators at the high-energy Los Alamos Neutron Science Center white neutron source at the Weapons Neutron Research facility as part of the joint LANL-LLNL Chi-Nu experimental campaign to measure actinide fission neutron spectra. These measurements are the first of their kind, and provide clear experimental evidence for second-chance fission, third-chance fission, and pre-equilibrium neutron emission processes in neutron-induced fission of 240 Pu, and are the first ever measurements above 1 MeV incident neutron energy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Road to PROSPECT-II

The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment is based in a segmented liquid scintillator antineutrino detector situated approximately 7 meters from the highly enriched High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Its main goal is to investigate short-baseline antineutrino oscillations. The first phase of data collection, known as PROSPECT-I, was held from 2018 to 2019 and was used for several high-precision analyses, including multiple measurements of the $^{235}U$ antineutrino spectrum and searches for $eV$-scale sterile antineutrino oscillations. The collaboration is now preparing for the second phase, PROSPECT-II, which features an upgraded detector design. This advancement will enhance sensitivity and statistical power, allowing for a broader range of analyses beyond those achieved in PROSPECT-I. As we transition into this new phase, new questions have arisen concerning background simulation and its potential differences from those conducted during the initial phase of the experiment. Moreover, it is essential to ascertain, through simulations, the positive effects that an improved detector could have on the study of oscillations. This information is crucial for justifying the proposed enhancements, and I will cover all of this in the talk.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Three-Flavor Neutrino Oscillations at NOvA

NOvA, is a two-detector, long-baseline neutrino oscillation experiment located at Fermilab, Batavia, IL, USA. It is designed primarily to constrain neutrino oscillation parameters such as the atmospheric mass squared splitting, $\Delta m^2_{32}$, the mixing angle, $\theta_{23}$, neutrino mass hierachy, and the CP-violating phase, $\delta_{CP}$, using $\nu_\mu \ (\bar{\nu}_\mu)$ disappearance and $\nu_e \ (\bar{\nu}_e)$ appearance data. NOvA receives a high purity 900 KW instense beam of neutrinos and anti-neutrinos from Fermilab's Neutrinos at Main Injector (NuMI) beamline. NOvA used functionally identical finely granulated liquid scintillation detectors, both situated 14.6 mrad off-axis to the beam direction. The NOvA near detector observes un-oscillated $\nu_\mu \ (\bar{\nu}_\mu)$ and beam $\nu_e \ (\bar{\nu}_e)$ events, while the far detector, which is situated 809 km away from the near detector, records un-oscillated $\nu_\mu \ (\bar{\nu}_\mu)$ and oscillated $\nu_e \ (\bar{\nu}_e)$ events. We will discuss the neutrino oscillation analysis strategy at NOvA and the latest three-flavor oscillation results from 10 years of NOvA data in this talk.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Newest 3-Flavor Neutrino Oscillation Results from NOvA

NOvA is a long-baseline accelerator neutrino experiment based at the Fermi National Accelerator Laboratory observing the appearance of electron (anti)neutrinos and disappearance of muon (anti) neutrinos. The experiment consists of two functionally identical liquid scintillator detectors; a 14 kton Far Detector is situated 810 km from the beam source, while a smaller Near Detector is only 1 km from the source and samples initial beam composition consisting of primarily muon (anti)neutrinos. Through these observations NOvA is probing outstanding questions in neutrino physics including the neutrino mass ordering and leptonic CP violation along with the θ23 neutrino mixing angle and the larger neutrino mass splitting Δm232. This talk will present the most recent neutrino oscillation results, which include a larger dataset, new analysis techniques, and updated systematic uncertainties.

Sutton, Andrew↗

DOE OSTI2022

Improvements to the 115g/115m Cd Nuclear Data

Repeated measurements of the isotope 115m Cd by Los Alamos National Laboratory (LANL), Pacific Northwest National Laboratory (PNNL), and Atomic Weapons Establishment (AWE) have revealed a consistent discrepancy between beta and gamma counting. This suggests that a significant disparity exists between the true value of the isotope’s gamma-ray branching ratios and the values reported by the National Nuclear Data Center (NNDC). Enriched 114 Cd was irradiated using thermal neutrons to produce a high-purity 115m/g Cd source for counting and analysis using traditional singles gamma-ray spectroscopy, liquid scintillation counting, gas-proportional counting, and analysis using the new Gamma-Alpha-Beta-Gamma (GABγ) and Gamma-Alpha-Beta Radio-Isotope EvaLuator (GABRIEL) coincidence detection systems. Using the D-T fusion generated neutrons, reduces the wait time required to let the short-lived 115Cd ground state decay away by leveraging the 1:1 production ratio of the ground and metastable state of 115 Cd from the 115 In (n,p) reaction relative to the 10:1 production ratio of the ground and metastable isotopes of 115 Cd by thermal neutron capture on 114 Cd. However, the much higher flux in from the Washington State University TRIGA reactor is a more rapid method of production of 115m/gCd but requires access to enriched 114 Cd. High purity 115m/g Cd samples were analyzed on regular intervals over a period of 140-days. The activity of 115m Cd measured by beta and gamma show a clear discrepancy using the current best known gamma-ray decay branching ratios. Based on these observations and measurements, a set of new branching ratio recommendations have been produced using conventional counting techniques and the advanced GAB? and GABRIEL instruments.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2025

Neutrino Oscillations at the NOvA Experiment

The NOvA experiment is a long-baseline neutrino oscillation experiments based at Fermi National Accelerator Laboratory in IL, USA. The experiment was designed to observe muon neutrino (muon anti-neutrino) disappearance and electron neutrino (electron anti-neutrino) appearance oscillations using a set of technological identical liquid scintillation detectors. The detectors are situated 14.6 milli-radians off-axis to the Fermilab's NuMI beam line that provides a beam of neutrinos (anti-neutrinos) to the experiment. The latest results from 3-flavor neutrino oscillation analysis from 10 years of NOvA data will be discussed in the talk.

Choudhary, Brajesh [Delhi U.]↗

DOE OSTI2025

Neutrino Oscillations at the NOvA Experiment

NOvA is a long-baseline neutrino oscillation experiment located at Fermi National Accelerator Laboratory (Fermilab) in Batavia, IL, USA. Its main goal is to extract neutrino oscillation parameters by examining the disappearance of $\nu_\mu \ (\bar{\nu}_\mu)$ and the appearance of $\nu_e \ (\bar{\nu}_e)$ at its far detector. The experiment uses the NuMI beamline at Fermilab, which delivers a high-purity neutrino and antineutrino beam. NOvA consists of two functionally similar, high-resolution liquid scintillator tracking calorimeters, both placed 14.6 milliradians off the beam axis. The near detector, positioned 100 m underground and 1 km from the beam's origin, captures unoscillated $\nu_\mu (\bar{\nu}_\mu)$ and instrinsic beam $\nu_e \ (\bar{\nu}_e)$ events. The far detector, located 810 km away from the beam source in Ash River, Minnesota, measures both unoscillated $\nu_\mu \ (\bar{\nu}_\mu)$ and those that have oscillated into $\nu_\mu \ (\bar{\nu}_\mu) \to \nu_e \ (\bar{\nu}_e)$. This poster will cover the latest results on three-flavor neutrino oscillation parameters, derived from an exposure of neutrino beam of $26.60 \times 10^{20}$ POT and anti-neutrino beam exposure of $12.50\times 10^{20}$ POT including an additional low energy $\nu_e$ sample.

Singh, Ishwar [Delhi U.]↗

DOE OSTI2026

Identification of Final-State Neutrons in ANNIE

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is a 26-ton gadolinium-loaded (Gd-loaded) water Cherenkov detector located on the Booster Neutrino beamline at Fermilab. ANNIE's primary physics objectives include measuring neutron multiplicity for neutrino-nucleus interactions and performing cross-section measurements of charge current quasi-elastic and neutral current quasi-elastic processes. These measurements aim to improve neutrino energy reconstruction and reduce uncertainties in current and future neutrino oscillation experiments. Additionally, ANNIE serves as a testbed for advanced technologies such as Large Area Picosecond Photodetectors (LAPPDs) and Water-Based Liquid Scintillator, which enhance vertex resolution and enable detection below the Cherenkov threshold. By leveraging the high neutron capture cross section of Gd-loaded water, ANNIE is well positioned to observe final-state neutrons in beam-correlated neutrino interactions. To constrain the uncertainties in the neutron capture efficiency and time within the detector, we have conducted multiple calibration campaigns using an AmBe source. The AmBe source is deployed at different locations of the tank to map the neutron capture efficiency and determine the expected neutron capture time. Additionally, the AmBe calibration data are used to define the precise neutron clustering that will be useful for identifying neutron-like clusters from neutrino interaction. In this poster, we will present the current status of the AmBe neutron calibration program and the development of neutron cluster definition for the ANNIE Experiment.

Ajana, Dhavalkumar [Florida State U.]↗