arXiv subjects

Geon-Bo Kim

Publications and source records attributed to Geon-Bo Kim.

4 recordsLinked to original sources

arXiv2026

Nuclear Data Needs for Microcalorimetry and Non-destructive Assay

Cryogenic microcalorimeters are state-of-the-art radiation detectors using superconducting and quantum technologies. They can resolve complex X-ray and low-energy {\gamma}-ray spectra with ultra-high energy resolution of an order of 10 eV at 100 keV, enabling high-precision non-destructive assay (NDA) analysis of nuclear materials containing uranium, plutonium and other actinides. With significant technical advancements in microcalorimetry technology, microcalorimeters are now deployable to end-users such as the International Atomic Energy Agency (IAEA) for improved NDA. However, the accuracy of microcalorimetry analysis can be limited by nuclear data. There are several cases that the current nuclear data obtained by conventional radiation detector technologies is not sufficient to support microcalorimetry analysis. To address the growing need for improved nuclear data in microcalorimetry, the U.S. Department of Energy Office of International Nuclear Safeguards hosted a workshop on Microcalorimetry and Nuclear Data (MiND) in June 2023. Microcalorimetry experts and users, and nuclear structure evaluators and managers, and program sponsors attended the workshop with the main objective of identifying a roadmap for priority nuclear data, stakeholders, partnerships, and opportunities. This paper summarizes the outcome of the MiND workshop, including the priority list of nuclear data for microcalorimetry and a multi-laboratory measurement campaign to improve such nuclear data.

physics.ins-det↗

arXiv2024

Signal processing and spectral modeling for the BeEST experiment

The Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) experiment searches for evidence of heavy neutrino mass eigenstates in the nuclear electron capture decay of $^7$Be by precisely measuring the recoil energy of the $^7$Li daughter. In Phase-III, the BeEST experiment has been scaled from a single superconducting tunnel junction (STJ) sensor to a 36-pixel array to increase sensitivity and mitigate gamma-induced backgrounds. Phase-III also uses a new continuous data acquisition system that greatly increases the flexibility for signal processing and data cleaning. We have developed procedures for signal processing and spectral fitting that are sufficiently robust to be automated for large data sets. This article presents the optimized procedures before unblinding the majority of the Phase-III data set to search for physics beyond the standard model.

physics.ins-det↗

arXiv2024

Direct Experimental Constraints on the Spatial Extent of a Neutrino Wavepacket

Despite their high relative abundance in our Universe, neutrinos are the least understood fundamental particles of nature. They also provide a unique system to study quantum coherence and the wavelike nature of particles in fundamental systems due to their extremely weak interaction probabilities. In fact, the quantum properties of neutrinos emitted in experimentally relevant sources are virtually unknown and the spatial extent of the neutrino wavepacket is only loosely constrained by reactor neutrino oscillation data with a spread of 13 orders of magnitude. Here, we present the first direct limits of this quantity through a new experimental concept to extract the energy width, $\sigma_{\textrm{N},E}$, of the recoil daughter nucleus emitted in the nuclear electron capture (EC) decay of $^7$Be. The final state in the EC decay process contains a recoiling $^7$Li nucleus and an electron neutrino ($\nu_e$) which are entangled at their creation. The $^7$Li energy spectrum is measured to high precision by directly embedding $^7$Be radioisotopes into a high resolution superconducting tunnel junction that is operated as a cryogenic sensor. The lower limit on the spatial uncertainty of the recoil daughter was found to be $\sigma_{\textrm{N}, x} \geq 6.2$\,pm, which implies the final-state system is localized at a scale more than a thousand times larger than the nucleus itself. From this measurement, the first direct lower limits on the spatial extent of the neutrino wavepacket were extracted using two different theoretical methods. These results have wide-reaching implications in several areas including the nature of spatial localization at sub-atomic scales, interpretation of neutrino physics data, and the potential reach of future large-scale experiments.

nucl-ex↗

arXiv2022

Report of the Topical Group on Particle Dark Matter for Snowmass 2021

This report summarizes the findings of the CF1 Topical Subgroup to Snowmass 2021, which was focused on particle dark matter. One of the most important scientific goals of the next decade is to reveal the nature of dark matter (DM). To accomplish this goal, we must delve deep, to cover high priority targets including weakly-interacting massive particles (WIMPs), and search wide, to explore as much motivated DM parameter space as possible. A diverse, continuous portfolio of experiments at large, medium, and small scales that includes both direct and indirect detection techniques maximizes the probability of discovering particle DM. Detailed calibrations and modeling of signal and background processes are required to make a convincing discovery. In the event that a candidate particle is found through different means, for example at a particle collider, the program described in this report is also essential to show that it is consistent with the actual cosmological DM. The US has a leading role in both direct and indirect detection dark matter experiments -- to maintain this leading role, it is imperative to continue funding major experiments and support a robust R\&D program.

hep-ph↗