H. M. O’Keeffe
A5055485746- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Muon and positron interactions and applications
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Planetary Science and Exploration
- Nuclear physics research studies
- Nuclear Physics and Applications
- Gamma-ray bursts and supernovae
- Noncommutative and Quantum Gravity Theories
- Urban Heat Island Mitigation
- Greenhouse Technology and Climate Control
- Radioactive contamination and transfer
- X-ray Spectroscopy and Fluorescence Analysis
- Particle Accelerators and Free-Electron Lasers
- Electron and X-Ray Spectroscopy Techniques
- Nuclear Issues and Defense
- Vascular Tumors and Angiosarcomas
- Amyloidosis: Diagnosis, Treatment, Outcomes
- Dermatological and Skeletal Disorders
- High-Energy Particle Collisions Research
Lancaster University
2016-2025
University of Bern
2023
Albert Einstein College of Medicine
2023
Eötvös Loránd University
2023
Boston University
2013-2023
Duke University
2018-2023
Universidad Autónoma de Madrid
2018-2023
University of California, Irvine
2013-2023
Colorado State University
2021-2023
Queen's University
2005-2021
We report results from a combined analysis of solar neutrino data all phases the Sudbury Neutrino Observatory (SNO). By exploiting particle identification information obtained proportional counters installed during third phase, this improved background rejection in that phase experiment. The SNO resulted total flux active flavors ${}^{8}\mathrm{B}$ decays Sun...
Results are reported from a joint analysis of Phase I and II data the Sudbury Neutrino Observatory. The effective electron kinetic energy threshold used is ${T}_{\mathrm{eff}}=3.5$ MeV, lowest yet achieved with water Cherenkov detector data. In units ${10}^{6}$ cm${}^{\ensuremath{-}2}$ ${\mathrm{s}}^{\ensuremath{-}1}$, total flux active-flavor neutrinos $^{8}\mathrm{B}$ decay in Sun measured using neutral current (NC) reaction on deuterons, no constraint neutrino spectrum, found to be...
The T2K experiment studies oscillations of an off-axis muon neutrino beam between the J-PARC accelerator complex and Super-Kamiokande detector. Special emphasis is placed on measuring mixing angle theta_13 by observing electron appearance via sub-dominant to oscillation, searching for CP violation in lepton sector. includes a sophisticated, off-axis, near detector, ND280, situated 280 m downstream production target order measure properties understand better interactions at energy scale below...
Neutron-antineutron oscillations in nature would violate baryon number and indicate a potential underlying mechanism for the observed matter-antimatter asymmetry. Sudbury Neutrino Observatory reports limits on neutron-antineutron first time deuteron. These establish important constraints beyond-the-Standard-Model scenarios that involve baryon-number violation.
The direction of individual <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mmultiscripts><a:mrow><a:mi mathvariant="normal">B</a:mi></a:mrow><a:mprescripts/><a:none/><a:mrow><a:mn>8</a:mn></a:mrow></a:mmultiscripts></a:mrow></a:math> solar neutrinos has been reconstructed using the <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:mi>SNO</d:mi><d:mo>+</d:mo></d:mrow></d:math> liquid scintillator detector. Prompt, directional...
Abstract The SNO $$+$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>+</mml:mo> </mml:math> collaboration reports its first spectral analysis of long-baseline reactor antineutrino oscillation using 114 tonne-years data. Fitting the neutrino probability to observed energy spectrum yields constraints on mass-squared difference $$\Delta m^2_{21}$$ <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msubsup> <mml:mi>m</mml:mi> <mml:mn>21</mml:mn> <mml:mn>2</mml:mn> </mml:msubsup> </mml:mrow>...
The long baseline between Earth and the Sun makes solar neutrinos an excellent test beam for exploring possible neutrino decay. signature of such decay would be energy-dependent distortion traditional survival probability which can fit using well-developed high-precision analysis methods. Here a model including is to all three phases 8B data taken by Sudbury Neutrino Observatory (SNO). This constrains lifetime mass state ν2 >8.08×10−5 s/eV at 90% confidence. An combining this SNO result with...
A measurement of the $^{8}\mathrm{B}$ solar neutrino flux has been made using a 69.2 kt-day dataset acquired with $\mathrm{SNO}+$ detector during its water commissioning phase. At energies above 6 MeV is an extremely pure sample elastic scattering events, owing primarily to detector's deep location, allowing accurate relatively little exposure. In that energy region best fit background rate $0.2{5}_{\ensuremath{-}0.07}^{+0.09}\text{ }\text{...
The SNO+ Collaboration reports the first evidence of reactor antineutrinos in a Cherenkov detector. nearest nuclear reactors are located 240 km away Ontario, Canada. This analysis uses events with energies lower than any previous large water Two analytical methods used to distinguish from background 190 days data and yield consistent for combined significance 3.5σ.
A search has been made for neutrinos from the hep reaction in Sun and diffuse supernova neutrino background (DSNB) using data collected during first operational phase of Sudbury Neutrino Observatory, with an exposure 0.65 kilotonne-years. For search, two events are observed effective electron energy range 14.3 MeV <T_eff< 20 where 3.1 expected. After accounting oscillations, upper limit 2.3x10^4 cm^-2s^-1 at 90% confidence level is inferred on integral total flux neutrinos. DSNB neutrinos,...
A search has been made for sinusoidal periodic variations in the $^8$B solar neutrino flux using data collected by Sudbury Neutrino Observatory over a 4-year time interval. The variation at period of one year is consistent with modulation Earth's orbital eccentricity. No significant periodicities are found periods between 1 day and 10 years either an unbinned maximum likelihood analysis or Lomb-Scargle periodogram analysis. inconsistent hypothesis that results recent Sturrock et al., based...
Results are reported on the measurement of atmospheric neutrino-induced muon flux at a depth 2 kilometers below Earth's surface from 1229 days operation Sudbury Neutrino Observatory (SNO). By measuring through-going muons as function zenith angle, SNO experiment can distinguish between oscillated and unoscillated portion neutrino flux. A total 514 muonlike events measured $\ensuremath{-}1\ensuremath{\le}\mathrm{cos}{\ensuremath{\theta}}_{\mathrm{zenith}}\ensuremath{\le}0.4$ in exposure...
Experimental tests of Lorentz symmetry in systems all types are critical for ensuring that the basic assumptions physics well founded. Data from phases Sudbury Neutrino Observatory, a kiloton-scale heavy water Cherenkov detector, analyzed possible violations neutrino sector. Such would appear as one eight signal detector: six seasonal variations solar electron survival probability differing energy and time dependence two shape changes to oscillated spectrum. No evidence such signals is...
We have performed three searches for high-frequency signals in the solar neutrino flux measured by Sudbury Neutrino Observatory (SNO), motivated possibility that $g$-mode oscillations could affect production or propagation of $^8$B neutrinos. The first search looked any significant peak frequency range 1/day to 144/day, with a sensitivity sinusoidal amplitudes 12% greater. second focused on regions which been claimed experiments aboard SoHO satellite, and was sensitive 10% third extra power...
The $$\alpha $$ -particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, -particles were produced in scintillator via $$^{12}$$ C(n, ) $$^9$$ Be reactions. second was loaded 2 % $$^{\mathrm {nat}}$$ Sm providing an -emitter, $$^{147}$$ Sm, as internal source. third a flask deployed into water-filled SNO+ detector and radioactive contaminants $$^{222}$$ Rn, $$^{218}$$ Po...
A search has been performed for neutrinos from two sources, the $hep$ reaction in solar $pp$ fusion chain and $\nu_e$ component of diffuse supernova neutrino background (DSNB), using full dataset Sudbury Neutrino Observatory with a total exposure 2.47 kton-years after fiducialization. The is both single-bin counting analysis likelihood fit. We find best-fit flux that compatible model predictions while remaining consistent zero flux, set one-sided upper limit $\Phi_{hep} <...
Results are reported from a search for low-multiplicity neutrino bursts in the Sudbury Neutrino Observatory (SNO). Such could indicate detection of nearby core-collapse supernova explosion. The data were taken Phase I (November 1999 - May 2001), when detector was filled with heavy water, and II (July 2001 August 2003), NaCl added to target. blind analysis which potential backgrounds estimated cuts developed eliminate such 90% confidence before examined. maintained greater than 50%...
This paper reports results from a search for single and multi-nucleon disappearance the $^{16}$O nucleus in water within \snoplus{} detector using all of available data. These so-called "invisible" decays do not directly deposit energy but are instead detected through their subsequent nuclear de-excitation gamma-ray emission. New limits given partial lifetimes: $\tau(n\rightarrow inv) > 9.0\times10^{29}$ years, $\tau(p\rightarrow 9.6\times10^{29}$ $\tau(nn\rightarrow 1.5\times10^{28}$...
The $\mathrm{SNO}+$ experiment collected data as a low-threshold water Cherenkov detector from September 2017 to July 2019. Measurements of the 2.2-MeV $\ensuremath{\gamma}$'s produced by neutron capture on hydrogen were made using an Am-Be calibration source, for which large fraction emitted neutrons are simultaneously with 4.4-MeV $\ensuremath{\gamma}$. Analysis delayed coincidence between $\ensuremath{\gamma}$ and revealed detection efficiency that is centered around 50% varies at level...