A. Lennarz
A5059042024- Nuclear physics research studies
- Atomic and Molecular Physics
- Neutrino Physics Research
- Astronomical and nuclear sciences
- Nuclear Physics and Applications
- Particle physics theoretical and experimental studies
- Atomic and Subatomic Physics Research
- Quantum Chromodynamics and Particle Interactions
- Mass Spectrometry Techniques and Applications
- Quantum, superfluid, helium dynamics
- Astro and Planetary Science
- Particle accelerators and beam dynamics
- Advanced NMR Techniques and Applications
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Nuclear reactor physics and engineering
- Isotope Analysis in Ecology
- Ion-surface interactions and analysis
- Advanced Chemical Physics Studies
- Stellar, planetary, and galactic studies
- Diamond and Carbon-based Materials Research
- Radiation Detection and Scintillator Technologies
- Superconducting and THz Device Technology
- Analytical chemistry methods development
TRIUMF
2015-2025
McMaster University
2021-2025
University of Münster
2010-2017
University of British Columbia
2012
Max Planck Institute for Nuclear Physics
2012
University of Manitoba
2012
National Superconducting Cyclotron Laboratory
2012
Michigan State University
2012
Simon Fraser University
2012
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...
We present precision Penning trap mass measurements of neutron-rich calcium and potassium isotopes in the vicinity neutron number N=32. Using TITAN system, 51K was measured for first time, (51,52)Ca values were improved significantly. The new show a dramatic increase binding energy compared to those reported atomic evaluation. In particular, 52Ca is more bound by 1.74 MeV, behavior with deviates substantially from tabulated values. An increased predicted recently based on calculations that...
TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) constitutes the only high precision mass measurement setup coupled to a rare isotope facility capable of increasing charge state short-lived nuclides prior actual determination in Penning trap. Recent developments around TITAN's breeder, electron beam ion trap, form basis several successful experiments on radioactive isotopes with half-lives as low 65 ms states 22+.
The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (${}^{3}$He,$t$) charge-exchange experiment on the double-beta ($\ensuremath{\beta}\ensuremath{\beta}$) decaying nucleus ${}^{100}$Mo. was carried out at Osaka University Research Center for Nuclear Physics (RCNP) with 420 MeV incident ${}^{3}$He beam and Grand Raiden magnetic spectrometer. A final-state energy resolution of 33 keV achieved. It found that nearly entire low-energy (up to...
The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (${}^{3}$He,$t$) charge-exchange experiment on the double-beta ($\ensuremath{\beta}\ensuremath{\beta}$) decaying nucleus ${}^{96}$Zr. was carried out at Osaka University Research Center for Nuclear Physics (RCNP) with 420 MeV incident ${}^{3}$He beam and Grand Raiden magnetic spectrometer. A final-state energy resolution of 32 keV achieved. large fraction low-energy GT${}^{\ensuremath{-}}$ is identified...
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...
Abstract Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand engines astronomical objects origin chemical elements. This white paper summarizes progress status field, new open questions that have emerged, tremendous scientific opportunities opened up with major advances in capabilities across an ever growing number disciplines subfields need be integrated. We take holistic view discussing unique challenges regards science,...
A ${}^{76}$Ge(${}^{3}$He,$t$)${}^{76}$As charge-exchange experiment at an incident energy of 420 MeV has been performed with resolution 30 keV. The Gamow-Teller GT${}^{\ensuremath{-}}$ strength distribution in ${}^{76}$As, which is the intermediate nucleus double-beta ($\ensuremath{\beta}\ensuremath{\beta}$) decay ${}^{76}$Ge, extracted. An unusually strong fragmentation observed even low excitation energies...
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...
This Letter reports on the first cross-section measurements for Sr94(α,n)Zr97 and Kr86(α,n)Sr89 reactions. In particular, our measurement of is weak r-process reaction cross section obtained using a radioactive ion beam. experiment was enabled by use novel solid helium targets, comprised silicon thin films with high incorporation via sputtering technique. Yield were performed at center-of-mass energies 10.4 9.0 MeV reaction, 9.9 Sr94(α,n)Zr97, extending into respective Gamow energy windows...
A (${}^{3}\text{He},t$) charge-exchange reaction experiment on the double-beta decaying nucleus ${}^{136}$Xe has been performed at an incident energy of 420 MeV with objective to measure Gamow-Teller (GT) strength distribution in ${}^{136}$Cs. The measurements have carried out dispersion-matched WS beam line and Grand Raiden spectrometer Research Center for Nuclear Physics Osaka, where resolution 42 keV was achieved. new gas cell thin windows made polyethylene naphthalate employed as a...
Gamow-Teller (GT) strength distributions have been investigated in a high-resolution (${}^{3}$He,$t$) charge-exchange experiment on the double-$\ensuremath{\beta}$ ($\ensuremath{\beta}\ensuremath{\beta}$ ) decaying nuclei ${}^{128}$Te and ${}^{130}$Te. The was carried out at Research Center for Nuclear Physics, Osaka, with 420-MeV incident ${}^{3}$He beam Grand Raiden magnetic spectrometer. A final-state energy resolution of 35 keV achieved. extracted GT low excitation energies final...
We report a direct measurement of the ${Q}_{\ensuremath{\beta}\ensuremath{\beta}}$ value neutrinoless double-$\ensuremath{\beta}$-decay candidate ${}^{48}\mathrm{Ca}$ at TITAN Penning-trap mass spectrometer, with result that ${Q}_{\ensuremath{\beta}\ensuremath{\beta}}=4267.98(32)\phantom{\rule{0.28em}{0ex}}\text{keV}$. measured masses both mother and daughter nuclides, in latter case found 1 keV deviation from literature value. In addition to value, we also present results new calculation...
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...
We present a first direct Q-value measurement of the Ga71(ν,e−)Ge71 reaction using TITAN mass-measurement facility at ISAC/TRIUMF. The measurements were performed in Penning trap on neon-like 71Ga21+ and 71Ge22+ isobar separation on-line produced mother daughter nuclei through threshold charge breeding an electron-beam ion trap. In addition, isoionic samples 71Ge21+ stored concurrently provided separate measurement. Both independent result combined 233.5±1.2 keV, which is agreement with...
In this Letter, we introduce the concept of in-trap nuclear decay spectroscopy highly charged radioactive ions and describe its successful application as a novel spectroscopic tool. This is demonstrated by measurement properties mass $A=124$ (here, $^{124}\mathrm{In}$ $^{124}\mathrm{Cs}$) in electron-beam ion trap TITAN facility at TRIUMF. By subjecting trapped to an intense electron beam, are charge bred high states (i.e., equivalent removal $N$-shell electrons), increase storage times...
A high-resolution measurement of the ${}^{71}$Ga(${}^{3}$He,$t$)${}^{71}$Ge charge-exchange reaction extracts Gamow-Teller strength distribution in ${}^{71}$Ge and allows a precision evaluation expected solar-neutrino capture rate, assuming non-oscillation scenario. The new measurements can be used as benchmark for comparing to neutrino rates presence oscillations. With results, dominant statistical uncertainty ${}^{71}$Ga rate lies now solar fluxes from CNO cycle.
The ``island of inversion'' around ${}^{32}$Mg is one the most important paradigms for studying disappearance stabilizing ``magicity'' a shell closure. We present first Penning-trap mass measurements exotic nuclides ${}^{29\ensuremath{-}31}$Na and ${}^{30\ensuremath{-}34}$Mg, which allow precise determination empirical gap ${}^{32}$Mg. new value 1.10(3) MeV smallest observed any nuclide with canonical magic number.
We report a high-statistics measurement of the $L/K$ orbital electron capture ratio in $^{7}\mathrm{Be}$ embedded cryogenic Ta. The thin Ta film formed part high-resolution superconducting tunnel junction radiation detector that was used to identify signals from different decay channels. measured 0.070(7) is significantly larger than only previous this quantity and theoretical predictions include in-medium effects. This value uniquely sensitive probe 1s 2s overlaps with nucleus relevance...
A measurement of proton inelastic scattering 8He at 8.25A MeV TRIUMF shows a resonance 3.54(6) with width 0.89(11) MeV. The energy the state is in good agreement coupled cluster and no-core shell model continuum calculations, latter successfully describing measured as well. Its differential cross section analyzed phenomenological collective excitation form factor microscopic reaction channels framework consistently reveals large deformation parameter β2 = 0.40(3), consistent predictions...
Measurements of the elastic scattering cross section $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$ are important in order to improve constraints on theoretical models $^{4}\mathrm{He}(^{3}\mathrm{He},\ensuremath{\gamma})^{7}\mathrm{Be}$, a key reaction Big Bang nucleosynthesis solar neutrino production. The astrophysical $S$ factor for this is significant source uncertainty standard-solar-model prediction $^{7}\mathrm{Be}$ $^{8}\mathrm{B}$ fluxes. measurements reported literature do not extend low...
The study of stellar burning began just over 100 years ago. Nonetheless, we do not yet have a detailed picture the nucleosynthesis within stars and how impacts structure remnants evolution. Achieving this understanding will require precise direct measurements nuclear reactions involved. This report summarizes status for burning, focusing on developments last couple decades, offering prospectus near-future developments.