ALAobo Li

Aobo Li

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

The organizations/institutes from the scholar's latest article


Aobo Li has a total of 535 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    Machine Learning on Heterogeneous, Edge, and Quantum Hardware for Particle Physics

    by Julia Gonski, Jennifer Ott, Shiva Abbaszadeh, Sagar Addepalli, Matteo Cremonesi, Jennet Dickinson, Giuseppe Di Guglielmo, Yigit Erdem Ertorer, Lindsey Gray, Ryan Herbst, et al.

    The next generation of particle physics experiments will face an era of challenges in data acquisition, due to unprecedented data rates and volumes along with extreme environments and operational constraints. Harnessing these data for scientific discovery demands real-time inference and decision-making, intelligent data reduction, and efficient processing architectures beyond current capabilities. Crucial to the success of this experimental paradigm are several emerging technologies, such as artificial intelligence and machine learning, silicon microelectronics, and the advent of quantum algorithms and processing. Their intersection includes areas of research such as low-power and low-latency devices for edge computing, heterogeneous accelerator systems, reconfigurable hardware, codesign and synthesis strategies, readout for cryogenic or high-radiation environments, and analog computing. This white paper presents a community-driven vision to identify and prioritize research and development opportunities in hardware-based ML systems and corresponding physics applications, contributing toward a successful transition to the data frontier of fundamental science.

  • Open Access

    Probing the Solar B 8 Neutrino Fog with XENONnT

    by XENON Collaboration, E. Aprile, J. Aalbers, K. Abe, M. M. Abu Rmeileh, M. Adrover, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, et al.

    We report a 3.3 σ measurement of coherent elastic neutrino-nucleus scattering from solar B 8 neutrinos using a 6.77 t × yr exposure from the XENONnT experiment, inferring a solar B 8 neutrino flux of ( 5 − 2 + 3 ) × 10 6 cm − 2 s − 1 , consistent with previous measurements. In the presence of the B 8 “neutrino fog,” we find no evidence for light dark matter, and observe diminishing returns in sensitivity with increasing exposure. A 93% increase in exposure from the previous search improves the median sensitivity to the nucleon scattering cross section for a 5 GeV / c 2 spin-independent weakly interacting massive particle by 10%. The dataset was also used to measure the weak mixing angle at ∼ 0.02 GeV / c momentum transfer and constrain physics beyond the Standard Model.


  • Open Access

    CycleGAN-driven transfer learning for electronics response emulation in high-purity germanium detectors

    by Kevin Bhimani, Julieta Gruszko, Morgan Clark, John Wilkerson, Aobo Li

    High-purity germanium (HPGe) detectors are a key technology for rare-event searches such as neutrinoless double-beta decay ( 0 ν β β ) and dark matter experiments. Pulse shapes from these detectors vary with interaction topology and thus encode information critical for event classification. Pulse shape simulations (PSSs) are essential for modeling analysis cuts that distinguish signal events from backgrounds and for generating reliable simulations of energy spectra. Traditional PSS methods rely on a series of first-principles corrections to replicate the effect of readout electronics, requiring challenging fits over large parameter spaces and often failing to accurately model the data. We present a neural network architecture, the Cyclic Positional U-Net ( CPU-Net ) 7 7 https://github.com/aobol/CPU-Net . , that performs translations of simulated pulses so that they closely resemble measured detector signals. Using a cycle generative adversarial network framework, this response emulation network learns a data-driven mapping between simulated and measured pulses with high fidelity, without requiring a predetermined response model. We use data from a HPGe detector with an inverted-coaxial point contact geometry to show that CPU-Net effectively captures and reproduces critical pulse shape features, allowing more realistic simulations without detector-specific tuning. CPU-Net achieves up to a factor-of-four improvement in distribution-level agreement for pulse shape parameter reconstruction, while preserving the topology-dependent information required for pulse-shape discrimination.

  • Open Access

    Final Results of the Majorana Demonstrator’s Search for Double-Beta Decay of Ge76 to Excited States of Se76

    by I. J. Arnquist, F. T. Avignone, A. S. Barabash, E. Blalock, B. Bos, M. Busch, Y.-D. Chan, J. R. Chapman, C. D. Christofferson, P.-H. Chu, et al.

    Ge 76 can β β decay into three possible excited states of Se 76 , with the emission of two or, if the neutrino is Majorana, zero neutrinos. None of these six transitions have yet been observed. The was designed to study β β decay of Ge 76 using a low background array of high purity germanium detectors. With 98.2 kg-y of isotopic exposure, the emonstrator sets the strongest half-life limits to date for all six transition modes. For 2 ν β β to the 0 1 + state of Se 76 , this search has begun to probe for the first time half-life values predicted using modern many-body nuclear theory techniques, setting a limit of T 1 / 2 > 1.5 × 10 24 y (90% CL). Published by the American Physical Society 2025


  • Open Access

    An assay-based background projection for the MAJORANA DEMONSTRATOR using Monte Carlo Uncertainty Propagation

    by I. J. Arnquist, F. T. Avignone, A. S. Barabash, C. J. Barton, K. H. Bhimani, E. Blalock, B. Bos, M. Busch, T. S. Caldwell, Y. -D. Chan, et al.

    The background index is an important quantity which is used in projecting and calculating the half-life sensitivity of neutrinoless double-beta decay ($0νββ$) experiments. A novel analysis framework is presented to calculate the background index using the specific activities, masses and simulated efficiencies of an experiment's components as distributions. This Bayesian framework includes a unified approach to combine specific activities from assay. Monte Carlo uncertainty propagation is used to build a background index distribution from the specific activity, mass and efficiency distributions. This analysis method is applied to the MAJORANA DEMONSTRATOR, which deployed arrays of high-purity Ge detectors enriched in $^{76}$Ge to search for $0νββ$. The framework projects a mean background index of $\left[8.95 \pm 0.36\right] \times 10^{-4}$cts/(keV kg yr) from $^{232}$Th and $^{238}$U in the DEMONSTRATOR's components.

  • Open Access

    Generative models for simulation of KamLAND-Zen

    by Zhenghao Fu, Christopher Grant, Dominika M. Krawiec, Aobo Li, Lindley A. Winslow

    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.


  • Open Access

    Exotic Dark Matter Search with the Majorana Demonstrator

    by I. J. Arnquist, F. T. Avignone, A. S. Barabash, C. J. Barton, K. H. Bhimani, E. Blalock, B. Bos, M. Busch, M. Buuck, T. S. Caldwell, et al.

    With excellent energy resolution and ultralow-level radiogenic backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter (DM) models. In this work, we report new experimental limits on keV-scale sterile neutrino DM via the transition magnetic moment from conversion to active neutrinos νs→νa. We report new limits on fermionic dark matter absorption (χ+A→ν+A) and sub-GeV DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), and new exclusion limits for bosonic dark matter (axionlike particles and dark photons). These searches utilize the (1–100)-keV low-energy region of a 37.5-kg y exposure collected by the Demonstrator between May 2016 and November 2019 using a set of Ge76-enriched detectors whose surface exposure time was carefully controlled, resulting in extremely low levels of cosmogenic activation.


  • Open Access

    Generative Models for Simulation of KamLAND-Zen

    by Z. Fu, C. Grant, D. M. Krawiec, A. Li, L. Winslow

    The next generation of searches for neutrinoless double beta decay (0ν\b{eta}\b{eta}) 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 0ν\b{eta}\b{eta} is critical. Traditional Monte Carlo (MC) simulations can be supplemented by machine-learning-based generative models. In this work, we describe the performance of generative models designed for monolithic liquid scintillator detectors like KamLAND to produce highly accurate simulation data without a predefined physics model. We demonstrate its 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.

  • Open Access

    Majorana Demonstrator Data Release for AI/ML Applications

    by I. J. Arnquist, F. T. Avignone, A. S. Barabash, C. J. Barton, K. H. Bhimani, E. Blalock, B. Bos, M. Busch, M. Buuck, T. S. Caldwell, et al.

    The enclosed data release consists of a subset of the calibration data from the Majorana Demonstrator experiment. Each Majorana event is accompanied by raw Germanium detector waveforms, pulse shape discrimination cuts, and calibrated final energies, all shared in an HDF5 file format along with relevant metadata. This release is specifically designed to support the training and testing of Artificial Intelligence (AI) and Machine Learning (ML) algorithms upon our data. This document is structured as follows. Section I provides an overview of the dataset's content and format; Section II outlines the location of this dataset and the method for accessing it; Section III presents the NPML Machine Learning Challenge associated with this dataset; Section IV contains a disclaimer from the Majorana collaboration regarding the use of this dataset; Appendix A contains technical details of this data release. Please direct questions about the material provided within this release to liaobo77@ucsd.edu (A. Li).

  • Open Access

    Constraints on the decay of $^{180m}$Ta

    by I. J. Arnquist, F. T. Avignone, A. S. Barabash, C. J. Barton, K. H. Bhimani, E. Blalock, B. Bos, M. Busch, M. Buuck, T. S. Caldwell, et al.

    $^{180m}$Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known $β$ and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter and K-spin violation. For this study, we repurposed the MAJORANA DEMONSTRATOR, an experimental search for the neutrinoless double-beta decay of $^{76}$Ge using an array of high-purity germanium detectors, to search for the decay of $^{180m}$Ta. More than 17 kilograms, the largest amount of tantalum metal ever used for such a search was installed within the ultra-low background detector array. In this paper we present results from the first year of Ta data taking and provide an updated limit for the $^{180m}$Ta half-life on the different decay channels. With new limits up to 1.5 x $10^{19}$ years, we improved existing limits by one to two orders of magnitude. This result is the most sensitive search for a single $β$ and electron capture decay ever achieved.