K. G. Leach
A5064004820- Nuclear physics research studies
- Nuclear Physics and Applications
- Neutrino Physics Research
- Atomic and Molecular Physics
- Particle physics theoretical and experimental studies
- Atomic and Subatomic Physics Research
- Astronomical and nuclear sciences
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- Dark Matter and Cosmic Phenomena
- Advanced Chemical Physics Studies
- Nuclear reactor physics and engineering
- Quantum, superfluid, helium dynamics
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Mass Spectrometry Techniques and Applications
- Radioactive Decay and Measurement Techniques
- Advanced NMR Techniques and Applications
- Radioactive contamination and transfer
- Astrophysics and Cosmic Phenomena
- Medical Imaging Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Superconducting and THz Device Technology
- X-ray Spectroscopy and Fluorescence Analysis
- Rare-earth and actinide compounds
Colorado School of Mines
2016-2025
Facility for Rare Isotope Beams
2024-2025
Michigan State University
2023-2024
Northeastern University
2024
Nexen (Canada)
2023
TRIUMF
2013-2020
University of Guelph
2011-2020
Simon Fraser University
2014-2017
Technical University of Munich
2009
University of Cologne
2009
Abstract Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances ability create, cool, control complex molecules down quantum level, along with recent upcoming species production at several facilities around world, create compelling opportunity coordinate combine these efforts bring precision measurement extreme nuclei. In...
A precision mass investigation of the neutron-rich titanium isotopes $^{51\ensuremath{-}55}\mathrm{Ti}$ was performed at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The range measurements covers $N=32$ shell closure, overall uncertainties $^{52\ensuremath{-}55}\mathrm{Ti}$ values were significantly reduced. Our results conclusively establish existence weak effect $N=32$, narrowing down abrupt onset this closure. data compared with state-of-the-art ab initio model calculations...
Abstract The nEXO neutrinoless double beta (0 νββ ) decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon search for the in 136 Xe. Progress detector design, paired with higher fidelity its simulation an advanced data analysis, based on one used final results EXO-200, produce sensitivity prediction that exceeds half-life 10 28 years. Specifically, improvements have been made understanding production scintillation photons charge as...
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 wavelike nature systems due extremely weak interaction probabilities. In fact, properties emitted experimentally relevant sources virtually unknown spatial extent neutrino wavepacket is only loosely constrained by reactor oscillation data with spread 13 orders magnitude. Here, we present first direct limits...
From detailed spectroscopy of 110Cd and 112Cd following the β+/electron-capture decay 110,112In β− 112Ag, very weak branches from nonyrast states are observed. The transition rates determined measured branching ratios level lifetimes obtained with Doppler-shift attenuation method inelastic neutron scattering reveal collective enhancements that suggestive a series rotational bands. In 110Cd, γ band built on shape-coexisting intruder configuration is suggested. For 112Cd, 2+ 3+ γ-band members...
Sterile neutrinos are natural extensions to the standard model of particle physics and provide a possible portal dark sector. We report new search for existence sub-MeV sterile using decay-momentum reconstruction technique in decay $^{7}\mathrm{Be}$. The experiment measures total energy $^{7}\mathrm{Li}$ daughter atom from electron capture $^{7}\mathrm{Be}$ implanted into sensitive superconducting tunnel junction (STJ) quantum sensors. This first presents data single STJ operated at low...
The development of quantum optomechanics now allows mechanical sensors with femtogram masses to be controlled and measured in the regime. If element contains isotopes that undergo nuclear decay, measuring recoil sensor following decay reconstruction total momentum all emitted particles, including any neutral particles may escape detection traditional detectors. As an example, for weak decays neutrino can reconstructed on event-by-event basis. We present concept a single nanometer-scale...
A study of the ${\ensuremath{\beta}}^{+}$-electron capture decay ${}^{110}$In into levels ${}^{110}$Cd is combined with a reanalysis data from previous $(n,{n}^{\ensuremath{'}}\ensuremath{\gamma})$ reaction monoenergetic neutrons. The $\ensuremath{\gamma}\ensuremath{\gamma}$ coincidences leads to many new assignments $\ensuremath{\gamma}$ rays observed in reaction, permitting observation weak low-energy transitions, and setting stringent upper limits on unobserved branches. uncertainties...
Based on results from a measurement of weak decay branches observed following the β- 94Y and lifetime data study 94Zr by inelastic neutron scattering, collective structure is deduced in closed-subshell nucleus 94Zr. These establish shape coexistence The role subshells for nuclear collectivity suggested to be important.
``Ultralow'' $Q$-value $\ensuremath{\beta}$ decays are referred to as such due their low decay energies of less than $\ensuremath{\approx}1$ keV. Such a energy is possible when the parent nucleus an excited state in daughter, with close that $Q$ value. These interest potential new candidates for neutrino mass determination experiments and testing ground studies atomic interference effects nuclear process. In this paper, we provide updated evaluation data energy-level identify ultralow...
Passive radiative cooling materials, which provide without consuming electricity, are widely recognized as an important technology for reducing greenhouse gas emissions and delivering thermal comfort to less industrialized communities. Optimizing optical properties is of primary importance these but real-world utilization, ease application scalability also require significant emphasis. In this work, we embed the biomaterial hydroxyapatite, in form nanoscale fibers, within oil-based medium...
The s-wave neutron fraction of the 0+ levels in 12Be has been investigated for first time through 11Be(d,p) transfer reaction using a 5A MeV 11Be beam at TRIUMF, Canada. populated all known bound states 12Be. ground state spectroscopic factor was determined to be 0.28−0.07+0.03 while that long-lived 02+ excited 0.73−0.40+0.27. This observation, together with smaller effective separation energy indicates enhanced probability an extended density tail beyond 10Be core compared state.
The elusive β^{-}p^{+} decay was observed in ^{11}Be by directly measuring the emitted protons and their energy distribution for first time with prototype Active Target Time Projection Chamber an experiment performed at ISAC-TRIUMF. measured branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained presence a narrow resonance ^{11}B above proton separation energy.
From detailed spectroscopy of $^{110}\mathrm{Cd}$ and $^{112}\mathrm{Cd}$ following the ${\ensuremath{\beta}}^{+}/\mathrm{EC}$ decay $^{110,112}\mathrm{In}$ ${\ensuremath{\beta}}^{\ensuremath{-}}$ $^{112}\mathrm{Ag}$, presence very weak branches from nonyrast states is revealed. In $^{112}\mathrm{Cd}$, ${2}_{5}^{+}\ensuremath{\rightarrow}{0}_{4}^{+}$ ${4}_{6}^{+}\ensuremath{\rightarrow}{2}_{5}^{+}$ transitions are observed that yield...
The electroweak interaction in the standard model is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this Letter, we present most precise measurement of tensor currents low-energy regime examining β-ν[over ¯] correlation trapped ^{8}Li ions with Beta-decay Paul Trap. We find a_{βν}=-0.3325±0.0013_{stat}±0.0019_{syst} at 1σ for case coupling to right-handed neutrinos (C_{T}=-C_{T}^{'}), which consistent prediction.
The excited states of N=44 ^{74}Zn were investigated via γ-ray spectroscopy following ^{74}Cu β decay. By exploiting γ-γ angular correlation analysis, the 2_{2}^{+}, 3_{1}^{+}, 0_{2}^{+}, and 2_{3}^{+} in firmly established. branching E2/M1 mixing ratios for transitions deexciting measured, allowing extraction relative B(E2) values. In particular, 2_{3}^{+}→0_{2}^{+} 2_{3}^{+}→4_{1}^{+} observed first time. results show excellent agreement with new microscopic large-scale shell-model...
Proton inelastic scattering off a neutron halo nucleus, 11Li, has been studied in inverse kinematics at the IRIS facility TRIUMF. The aim was to establish soft dipole resonance and obtain its strength. Using high quality 66 MeV 11Li beam, strongly populated excited state observed Ex=0.80 +/- 0.02 with width of 1.15 0.06 MeV. A DWBA (distorted-wave Born approximation) analysis measured differential cross section isoscalar macroscopic form factors leads conclude that this is an electric (E1)...
Using the Penning trap mass spectrometer TITAN, we performed first direct measurements of $^{20,21}\mathrm{Mg}$, isotopes that are most proton-rich members $A=20$ and $A=21$ isospin multiplets. These were possible through use a unique ion-guide laser ion source, development suppressed isobaric contamination by 6 orders magnitude. Compared to latest atomic evaluation, find $^{21}\mathrm{Mg}$ is in good agreement but $^{20}\mathrm{Mg}$ deviates $3\ensuremath{\sigma}$. reduce uncertainties...
Large detectors employing xenon are a leading technology in existing and planned searches for new physics, including neutrinoless double beta decay ($0\nu\beta\beta$) dark matter. While upcoming will employ target masses of ton or more, further extending gas liquid phase Xe to the kton scale would enable extremely sensitive next-generation rare phenomena. The key challenge this well beyond is acquisition itself. We describe motivation time projection chambers (TPCs) possible avenues that...
The Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) experiment searches for evidence of heavy neutrino mass eigenstates the nuclear electron decay $^7$Be by precisely measuring recoil energy $^7$Li daughter. In Phase-III, BeEST has been scaled from a single superconducting tunnel junction (STJ) sensor to 36-pixel array increase sensitivity and mitigate gamma-induced backgrounds. Phase-III also uses new continuous data acquisition system that greatly increases...
A high-precision half-life measurement for the superallowed ${\ensuremath{\beta}}^{+}$ emitter $^{26}\mathrm{Al}^{m}$ was performed at TRIUMF-ISAC radioactive ion beam facility yielding ${T}_{1/2}=6346.54\ifmmode\pm\else\textpm\fi{}{0.46}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.60}_{\mathrm{syst}}\text{ }\text{ }\mathrm{ms}$, consistent with, but 2.5 times more precise than, previous world average. The and $ft$ value, 3037.53(61) s, are now most precisely determined any...
Shape coexistence between the strongly deformed ground state and weakly ${0}_{2}^{+}$ in $^{98}\mathrm{Sr}$ has been a major topic of interest due to energy difference 215 keV, which is smallest all even-even nuclei. The electric monopole transition strength ${\ensuremath{\rho}}^{2}(E0)$ an important quantity that can relate deformation shape mixing two ${0}^{+}$ states, are admixtures vibrational (S) rotational (D) states simple model. In $\ensuremath{\beta}$-decay spectroscopy experiment,...