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Steven R. Elliott

Publications and source records attributed to Steven R. Elliott.

12 recordsLinked to original sources
arXiv2026

Vision AI Agent for Continuous Material Monitoring of LEGEND-1000 LoFi Reentrant Tube

We report on a vision AI agent pipeline for non-contact material strain and property extraction from video data, demonstrated on video taken during hydrostatic testing of four OFHC copper cylinders conducted as part of the LEGEND-1000 hardware validation campaign. Traditional strain gauge measurements proved unreliable, motivating a fully-automated agentic alternative. The agent was built on the LangChain framework with Claude Haiku 4.5 as its central reasoning engine, integrating a specialized suite of computer vision tools: FFmpeg for video preprocessing and rotation correction via Hough Line Transform, the Segment Anything Model 2 (SAM2) for spatiotemporal segmentation with automated memory-informed dynamic chunking, and a hybrid EasyOCR and LLM-based timestamp validation pipeline. Three specialized sub-agents were developed to process the video data and obtain cylinder diameters and timestamps while autonomously handling obstacles such as corrupted frames and memory limits. From the diameter profiles synchronized to pressure data, hoop stress--strain curves were reconstructed and yield strengths were calculated using the 0.2\% offset, 0.5\% EUL, and Johnson-Cook methods across two independent tests. Cross-validation against a non-agentic pipeline confirmed agreement for the diameter extraction at the $\pm$5 pixel level. The material properties and testing results were further compared to Ansys mechanical simulations performed as part of the LEGEND-1000 reentrant tube design campaign. This work showcases the power of agentic pipelines to extract materials data from video alone.

physics.ins-det↗
arXiv2023

The Gallium Anomaly

In order to test the end-to-end operations of gallium solar neutrino experiments, intense electron-capture sources were fabricated to measure the responses of the radiochemical SAGE and GALLEX/GNO detectors to known fluxes of low-energy neutrinos. Such tests were viewed at the time as a cross-check, given the many tests of $^{71}$Ge recovery and counting that had been routinely performed, with excellent results. However, the four $^{51}$Cr and $^{37}$Ar source experiments yielded rates below expectations, a result commonly known as the Ga anomaly. As the intensity of the electron-capture sources can be measured to high precision, the neutrino lines they produce are fixed by known atomic and nuclear rates, and the neutrino absorption cross section on $^{71}$Ga is tightly constrained by the lifetime of $^{71}$Ge, no simple explanation for the anomaly has been found. To check these calibration experiments, a dedicated experiment BEST was performed, utilizing a neutrino source of unprecedented intensity and a detector optimized to increase statistics while providing some information on counting rate as a function of distance from the source. The results BEST obtained are consistent with the earlier solar neutrino calibration experiments, and when combined with those measurements, yield a Ga anomaly with a significance of approximately $4σ$, under conservative assumptions. But BEST found no evidence of distance dependence and thus no explicit indication of new physics. In this review we describe the extensive campaigns carried out by SAGE, GALLEX/GNO, and BEST to demonstrate the reliability and precision of their experimental procedures, including $^{71}$Ge recovery, counting, and analysis. We also describe efforts to define uncertainties in the neutrino capture cross section. With the results from BEST, an anomaly remains.

nucl-ex↗
arXiv2022

A Facility for Low-Radioactivity Underground Argon

The DarkSide-50 experiment demonstrated the ability to extract and purify argon from deep underground sources and showed that the concentration of $^{39}$Ar in that argon was greatly reduced from the level found in argon derived from the atmosphere. That discovery broadened the physics reach of argon-based detector and created a demand for low-radioactivity underground argon (UAr) in high-energy physics, nuclear physics, and in environmental and allied sciences. The Global Argon Dark Matter Collaboration (GADMC) is preparing to produce UAr for DarkSide-20k, but a general UAr supply for the community does not exist. With the proper resources, those plants could be operated as a facility to supply UAr for most of the experiments after the DarkSide 20k production. However, if the current source becomes unavailable, or UAr masses greater than what is available from the current source is needed, then a new source must be found. To find a new source will require understanding the production of the radioactive argon isotopes underground in a gas field, and the ability to measure $^{37}$Ar, $^{39}$Ar, and $^{42}$Ar to ultra-low levels. The operation of a facility creates a need for ancillary systems to monitor for $^{37}$Ar, $^{39}$Ar, or $^{42}$Ar infiltration either directly or indirectly, which can also be used to vet the $^{37}$Ar, $^{39}$Ar, and $^{42}$Ar levels in a new UAr source, but requires the ability to separate UAr from the matrix well gas. Finding methods to work with industry to find gas streams enriched in UAr, or to commercialize a UAr facility, are highly desirable.

physics.ins-det↗
arXiv2019

Ge Detectors and $0νββ$: The Search for Double Beta Decay with Germanium Detectors: Past, Present and Future

High Purity Germanium Detectors have excellent energy resolution; the best among the technologies used in double beta decay. Since neutrino-less double beta decay hinges on the search for a rare peak upon a background continuum, this strength has enabled the technology to consistently provide leading results. The Ge crystals at the heart of these experiments are very pure; they have no measurable U or Th contamination. The added efforts to reduce the background associated with electronics, cryogenic cooling, and shielding have been very successful, leading to the longevity of productivity. The first experiment published in 1967 by the Milan group of Fiorini, established the benchmark half-life limit $>3\times10^{20}$ yr. More recently, the \MJ\ and GERDA collaborations have developed new detector technologies that optimize the pulse waveform analysis. As a result, the GERDA collaboration refuted the claim of observation with a revolutionary approach to shielding by immersing the detectors directly in radio-pure liquid argon. In 2018, the \MJ\ collaboration, using a classic vacuum cryostat and high-Z shielding, achieved a background level near that of GERDA by developing very pure materials for use nearby the detectors. Together, GERDA and \MJ\ have provided limits approaching $10^{26}$ yr. In this article, we elaborate on the historical use of Ge detectors for double beta decay addressing the strengths and weaknesses. We also summarize the status and future as many \MJ\ and GERDA collaborators have joined with scientists from other efforts to give birth to the LEGEND collaboration. LEGEND will exploit the best features of both experiments to extend the half-life limit beyond $10^{28}$ yr with a ton-scale experiment.

nucl-ex↗
arXiv2017

Solar Axion Search Technique with Correlated Signals from Multiple Detectors

The coherent Bragg scattering of photons converted from solar axions inside crystals would boost the signal for axion-photon coupling enhancing experimental sensitivity for these hypothetical particles. Knowledge of the scattering angle of solar axions with respect to the crystal lattice is required to make theoretical predications of signal strength. Hence, both the lattice axis angle within a crystal and the absolute angle between the crystal and the Sun must be known. In this paper, we examine how the experimental sensitivity changes with respect to various experimental parameters. We also demonstrate that, in a multiple-crystal setup, knowledge of the relative axis orientation between multiple crystals can improve the experimental sensitivity, or equivalently, relax the precision on the absolute solar angle measurement. However, if absolute angles of all crystal axes are measured, we find that a precision of 2-4 degrees will suffice for an energy resolution of $σ_E=0.04{\rm E}$ and a flat background. Finally, we also show that, given a minimum number of detectors, a signal model averaged over angles can substitute for precise crystal angular measurements, with some loss of sensitivity.

hep-ex↗
arXiv2012

Recent Progress in Double Beta Decay

At least one neutrino has a mass of about 50 meV or larger. However, the absolute mass scale for the neutrino remains unknown. Studies of double beta decay offer hope for determining the absolute mass scale. Furthermore, the critical question: Is the neutrino its own antiparticle? is unanswered. In particular, zero-neutrino double beta decay can address the issues of lepton number conservation, the particle-antiparticle nature of the neutrino, and its mass. A summary of the recent progress in double beta decay, and the related technologies will be discussed in the context of the future double beta decay program.

nucl-ex↗
arXiv2011

Double Beta Decay

At least one neutrino has a mass of about 50 meV or larger. However, the absolute mass scale for the neutrino remains unknown. Furthermore, the critical question: Is the neutrino its own antiparticle? is unanswered. Studies of double beta decay offer hope for determining the absolute mass scale. In particular, zero-neutrino double beta decay (\BBz) can address the issues of lepton number conservation, the particle-antiparticle nature of the neutrino, and its mass. A summary of the recent results in \BBz, and the related technologies will be discussed in the context of the future \BBz\ program.

nucl-ex↗
arXiv2007

Double Beta Decay, Majorana Neutrinos, and Neutrino Mass

The theoretical and experimental issues relevant to neutrinoless double-beta decay are reviewed. The impact that a direct observation of this exotic process would have on elementary particle physics, nuclear physics, astrophysics and cosmology is profound. Now that neutrinos are known to have mass and experiments are becoming more sensitive, even the non-observation of neutrinoless double-beta decay will be useful. If the process is actually observed, we will immediately learn much about the neutrino. The status and discovery potential of proposed experiments are reviewed in this context, with significant emphasis on proposals favored by recent panel reviews. The importance of and challenges in the calculation of nuclear matrix elements that govern the decay are considered in detail. The increasing sensitivity of experiments and improvements in nuclear theory make the future exciting for this field at the interface of nuclear and particle physics.

nucl-ex↗
arXiv2003

Neutrino Mass Patterns and Future Double-Beta Decay Experiments

The next generation of double-beta decay experiments have an excellent chance of providing data on the neutrino mass pattern. This presentation is a summary of what is currently known about the mass pattern and expectations from experiment. Uncertainties due to the precision in the oscillation parameters are not critical to the interpretation of a zero-neutrino, double-beta decay measurement in terms of the mass pattern. Even though there is reason for optimism, the matrix element uncertainty is still a concern. A selected, representative group of the future experiments is discussed.

nucl-ex↗
arXiv2003

Experiments for Double-Beta Decay

The recent neutrino oscillation experimental results indicate that at least one neutrino has a mass greater than 50 meV. The next generation of double-beta decay experiments will very likely have a sensitivity to an effective Majorana neutrino mass below this target. Therefore this is a very exciting time for this field of research as even null results from these experiments have the potential to elucidate the nature of the neutrino.

nucl-ex↗
arXiv2002

Double Beta Decay

The motivation, present status, and future plans of the search for the neutrinoless double beta decay are reviewed. It is argued that, motivated by the recent observations of neutrino oscillations, there is a reasonable hope that neutrinoless double beta decay corresponding to the neutrino mass scale suggested by oscillations, of about 50 meV, actually exists. The challenges to achieve the sensitivity corresponding to this mass scale, and plans to overcome them, are described.

hep-ph↗