J. G. Learned
A5008496297- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Muon and positron interactions and applications
- Pulsars and Gravitational Waves Research
University of Hawaii System
2012-2024
University of Hawaiʻi at Mānoa
1988-2023
Cosmic-ray muons produce various radioisotopes when passing through material. These spallation products can be backgrounds for rare event searches such as in solar neutrino, double-$\ensuremath{\beta}$ decay, and dark matter search experiments. The KamLAND-Zen experiment neutrinoless decay 745 kg of xenon dissolved liquid scintillator. includes dead-time-free electronics with a high efficiency detecting muon-induced neutrons. production yields different are measured combination delayed...
Abstract The Super-Kamiokande detector can be used to search for neutrinos in time coincidence with gravitational waves detected by the LIGO–Virgo Collaboration (LVC). Both low-energy (7–100 MeV) and high-energy (0.1–10 5 GeV) samples were analyzed order cover a very wide neutrino spectrum. Follow-ups of 36 (out 39) reported GWTC-2 catalog examined; no significant excess above background was observed, 10 (24) observed compared 4.8 (25.0) expected events (low-energy) samples. A statistical...
We report new limits on the nucleon lifetime obtained with Irvine-Michigan-Brookhaven water Cherenkov detector. Techniques in track fitting, particle identification, and invariant-mass reconstruction provide information about multitrack events which leads to a significant reduction background for most decay modes. Data during initial 417-day run subsequent 69-day enhanced light collection are discussed. A subtraction is made, yielding 90%-confidence-level lower bounds partial per branching...
Radioactivity induced by cosmic muon spallation is a dominant source of backgrounds for <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi mathvariant="script">O</a:mi><a:mo stretchy="false">(</a:mo><a:mn>10</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>MeV</a:mi><a:mo stretchy="false">)</a:mo></a:mrow></a:math> neutrino interactions in water Cherenkov detectors. In particular, it crucial to reduce measure the solar spectrum and find from distant...
Antineutrinos from nuclear reactors have the potential to be used for reactor monitoring in mid- far-field under certain conditions. are an unshieldable signal and carry information about core distance they travel. Using gadolinium-doped water Cherenkov detectors this purpose has been previously proposed alongside rate-only analyses. As antineutrinos their of travel energy spectrum, analyses can extended a spectral analysis gain more knowledge detected core. A Fourier transform evaluate...
Particle dark matter could belong to a multiplet that includes an electrically charged state. WIMP ($\chi^{0}$) accompanied by negatively excited state ($\chi^{-}$) with small mass difference (e.g. $<$ 20 MeV) can form bound-state nucleus such as xenon. This formation is rare and the released energy $\mathcal{O}(1-10$) MeV depending on nucleus, making large liquid scintillator detectors suitable for detection. We searched events xenon in two experimental phases of KamLAND-Zen experiment,...
Cosmic-ray muons produce various radioisotopes when passing through material. These spallation products can be backgrounds for rare event searches such as in solar neutrino, double-beta decay, and dark matter search experiments. The KamLAND-Zen experiment neutrinoless decay 745kg of xenon dissolved liquid scintillator. includes dead-time-free electronics with a high efficiency detecting muon-induced neutrons. production yields different are measured combination delayed coincidence...
We report a measurement of the strange axial coupling constant $g_A^s$ using atmospheric neutrino data at KamLAND. This is component form factor neutral-current quasielastic (NCQE) interaction. The value significantly changes ratio proton and neutron NCQE cross sections. KamLAND suitable for measuring interactions as it can detect nucleon recoils with low-energy thresholds measure multiplicity high efficiency. data, including information on associated interactions, makes possible to...