arXiv subjects

D. H. Hwang

Publications and source records attributed to D. H. Hwang.

5 recordsLinked to original sources

arXiv2026

A study of neutrinoless double electron capture in $^{40}$Ca from the AMoRE experiment

The search for neutrinoless double electron capture ($0ν\mathrm{2EC}$) provides a sensitive probe of lepton-number violation and the Majorana nature of neutrinos. We investigate the $0ν\mathrm{2EC}$ decay of $^{40}$Ca using cryogenic detectors equipped with metallic magnetic calorimeters in the AMoRE-I experiment. The analysis is based on a physics dataset corresponding to a total exposure of 7.32 kg$\cdot$yr from thirteen $^{40}$Ca$^{100}$MoO$_4$ crystals. No significant excess is observed, and a lower limit on the half-life is obtained as $T^{0ν}_{1/2} > 1.7 \times 10^{22}$ yr at 90$\%$ confidence level. An improved sensitivity is expected for the upcoming AMoRE-II experiment. These results demonstrate the potential of CaMoO$_4$ detectors to explore rare decay processes beyond the primary $^{100}$Mo $0νββ$ search program.

nucl-ex↗

arXiv2026

LiFE-SNS: LiF Experiment for keV-scale Sterile Neutrino Search

The LiF Experiment for keV-scale Sterile Neutrino Search (LiFE-SNS) aims to probe sterile neutrinos through precision measurements of the tritium $β$ spectrum. Tritium nuclei are produced and embedded in LiF crystals via the ${}^{6}\mathrm{Li}(n,α){}^{3}\mathrm{H}$ reaction, allowing thermal calorimetric detection of $β$ decays with magnetic microcalorimeters (MMCs) operated at millikelvin temperatures. We present the detector configuration, background studies, and calibration method, including modeling of position-dependent response and characterization of detector nonlinearity. We also discuss potential sources of systematic uncertainty relevant to the sterile-neutrino search. While the first phase of LiFE-SNS has been completed, this paper focuses on calibration and detector characterization. The achieved performance enables precision $β$-spectrum measurements, and projected sensitivities indicate competitive reach in the keV mass region.

hep-ex↗

arXiv2025

Improved limit on neutrinoless double beta decay of $^{100}$Mo from AMoRE-I

AMoRE searches for the signature of neutrinoless double beta decay of $^{100}$Mo with a 100 kg sample of enriched $^{100}$Mo. Scintillating molybdate crystals coupled with a metallic magnetic calorimeter operate at milli-Kelvin temperatures to measure the energy of electrons emitted in the decay. As a demonstration of the full-scale AMoRE, we conducted AMoRE-I, a pre-experiment with 18 molybdate crystals, at the Yangyang Underground Laboratory for over two years. The exposure was 8.02 kg$\cdot$year (or 3.89 kg$_{\mathrm{^{100}Mo}}\cdot$year) and the total background rate near the Q-value was 0.025 $\pm$ 0.002 counts/keV/kg/year. We observed no indication of $0νββ$ decay and report a new lower limit of the half-life of $^{100}$Mo $0νββ$ decay as $ T^{0ν}_{1/2}>2.9\times10^{24}~\mathrm{yr}$ at 90\% confidence level. The effective Majorana mass limit range is $m_{ββ}<$(210--610) meV using nuclear matrix elements estimated in the framework of different models, including the recent shell model calculations.

nucl-ex↗

arXiv2025

Development of MMC-based lithium molybdate cryogenic calorimeters for AMoRE-II

The AMoRE collaboration searches for neutrinoless double beta decay of $^{100}$Mo using molybdate scintillating crystals via low temperature thermal calorimetric detection. The early phases of the experiment, AMoRE-pilot and AMoRE-I, have demonstrated competitive discovery potential. Presently, the AMoRE-II experiment, featuring a large detector array with about 90 kg of $^{100}$Mo isotope, is under construction. This paper discusses the baseline design and characterization of the lithium molybdate cryogenic calorimeters to be used in the AMoRE-II detector modules. The results from prototype setups that incorporate new housing structures and two different crystal masses (316 g and 517 - 521 g), operated at 10 mK temperature, show energy resolutions (FWHM) of 7.55 - 8.82 keV at the 2.615 MeV $^{208}$Tl $γ$ line, and effective light detection of 0.79 - 0.96 keV/MeV. The simultaneous heat and light detection enables clear separation of alpha particles with a discrimination power of 12.37 - 19.50 at the energy region around $^6$Li(n, $α$)$^3$H with Q-value = 4.785 MeV. Promising detector performances were demonstrated at temperatures as high as 30 mK, which relaxes the temperature constraints for operating the large AMoRE-II array.

physics.ins-det↗

arXiv2024

Background study of the AMoRE-pilot experiment

We report a study on the background of the Advanced Molybdenum-Based Rare process Experiment (AMoRE), a search for neutrinoless double beta decay (\znbb) of $^{100}$Mo. The pilot stage of the experiment was conducted using $\sim$1.9 kg of \CAMOO~ crystals at the Yangyang Underground Laboratory, South Korea, from 2015 to 2018. We compared the measured $β/γ$ energy spectra in three experimental configurations with the results of Monte Carlo simulations and identified the background sources in each configuration. We replaced several detector components and enhanced the neutron shielding to lower the background level between configurations. A limit on the half-life of $0νββ$ decay of $^{100}$Mo was found at $T_{1/2}^{0ν} \ge 3.0\times 10^{23}$ years at 90\% confidence level, based on the measured background and its modeling. Further reduction of the background rate in the AMoRE-I and AMoRE-II are discussed.

nucl-ex↗