Mark McCrea
A5070300922- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
- Nuclear physics research studies
- Quantum Chromodynamics and Particle Interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Neutrino Physics Research
- Radiation Detection and Scintillator Technologies
- Advanced Frequency and Time Standards
- Advanced NMR Techniques and Applications
- Scientific Research and Discoveries
- Particle Accelerators and Free-Electron Lasers
- Particle physics theoretical and experimental studies
- Geophysics and Gravity Measurements
- Hydrocarbon exploration and reservoir analysis
- Methane Hydrates and Related Phenomena
- Electrostatics and Colloid Interactions
- Black Holes and Theoretical Physics
- Quantum optics and atomic interactions
- Geophysics and Sensor Technology
- Advanced X-ray Imaging Techniques
- Magnetic confinement fusion research
University of Kentucky
2018-2024
University of Manitoba
2015-2024
University of Winnipeg
2020-2024
Campbell Collaboration
2022
North Carolina State University
2018
Thomas Jefferson National Accelerator Facility
2004
We report the first observation of parity-violating 2.2 MeV gamma-ray asymmetry $A^{np}_\gamma$ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at Spallation Neutron Source Oak Ridge National Laboratory. isolates $\Delta I=1$, \mbox{$^{3}S_{1}\rightarrow {^{3}P_{1}}$} component weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to single coupling constant either DDH meson model or pionless EFT....
Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding wide range questions in many-body physics. Unfortunately, pair correlation function $g(r)$ inferred neutron scattering measurements differential cross section $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}$ different reported literature inconsistent. We have measured energy dependence total slow neutrons...
Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover details weak interaction. can evaluate ratio axial-vector vector coupling constants standard model, λ = g A / V , through multiple correlations. The Nab experiment will carry out measurements electron-neutrino correlation parameter a with precision δ 10 −3 Fierz interference term b 3 × unpolarized free neutron decay. These results, along more precise measurement lifetime,...
We report the first precision measurement of parity-violating asymmetry in direction proton momentum with respect to neutron spin, reaction ^{3}He(n,p)^{3}H, using capture polarized cold neutrons an unpolarized active ^{3}He target. The is a result weak interaction between nucleons, which remains one least well-understood aspects electroweak theory. provides important benchmark for modern effective field theory and potential model calculations. Measurements like this are necessary determine...
The Nab experiment at Oak Ridge National Laboratory, USA, aims to measure the beta-antineutrino angular correlation following neutron $\ensuremath{\beta}$ decay an anticipated precision of approximately 0.1%. proton momentum is reconstructed through time-of-flight measurements, and potential systematic biases in timing reconstruction due detector effects must be controlled nanosecond level. We present a thorough detailed semiconductor quasiparticle transport simulation effort provide precise...
Novel experimental techniques are required to make the next big leap in neutron electric dipole moment sensitivity, both terms of statistics and systematic error control. The nEDM experiment at Spallation Neutron Source (nEDM@SNS) will implement scheme Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. unique properties combining polarized ultracold neutrons, 3 He, superfluid 4 He be exploited provide a sensitivity ∼ 10 −28 e · cm. Our cryogenic apparatus deploy two small (3 L) measurement...
We report the performance of a magnetically silent optically pumped cesium magnetometer with statistical sensitivity 3.9 pT and stability 90 fT over 150 seconds measurement. Optical pumping coherent, linearly-polarized, resonant light leads to relatively long-lived polarized ground state vapour contained in measurement cell. The precesses at its Larmor frequency magnetic field be measured. Nonlinear magneto-optical rotation then plane polarization linearly probe laser beam. angle is...
Abstract We report the performance of a magnetically silent optically pumped cesium magnetometer with statistical sensitivity 3.5 pT/ $$\sqrt{\textrm{Hz}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mtext>Hz</mml:mtext> </mml:msqrt> </mml:math> at 1 Hz and stability 90 fT over 150 s measurement. Optical pumping coherent, linearly-polarized, resonant light leads to relatively long-lived polarized ground state vapour contained in measurement cell. The precesses...
Recently, the Collaboration reported a measurement of parity-violating (PV) proton directional asymmetry in capture reaction 3He(⃗𝑛,𝑝)3H at meV incident neutron energies. The result increased limited inventory precisely measured and calculable PV observables few-body systems required to further understand structure hadronic weak interaction. In this Letter, we report experimental theoretical investigation parity conserving (PC) 𝐴PC same (the first ever PC observable energies). As S- P-wave...
This paper presents a new technique to study the adsorption and desorption of ions electrons on insulating surfaces in presence strong electric fields cryoliquids. The experimental design consists compact cryostat coupled with sensitive electro-optical Kerr device monitor stability fields. behavior nitrogen helium poly(methyl methacrylate) (PMMA) surface was compared PMMA coated mixture deuterated polystyrene polybutadiene. Ion accumulation removal these were unambiguously observed. Within...
This paper presents a new technique to study the adsorption and desorption of ions electrons on insulating surfaces in presence strong electric fields cryoliquids. The experimental design consists compact cryostat coupled with sensitive electro-optical Kerr device monitor stability fields. behavior nitrogen helium poly(methyl methacrylate) (PMMA) surface was compared PMMA coated mixture deuterated polystyrene polybutadiene. Ion accumulation removal these were unambiguously observed. Within...
Recently, the n$^3$He collaboration reported a measurement of parity-violating (PV) proton directional asymmetry $A_{\mathrm {PV}} = (1.55\pm 0.97~\mathrm {(st\ at)} \pm 0.24~\mathrm {(sys)})\times 10^{-8}$ in capture reaction ${}^3$He$(\vec {n},{\mathrm p}){}^3$H at meV incident neutron energies. The result increased limited inventory precisely measured and calculable PV observables few-body systems required to further understand structure hadronic weak interaction. In this letter, we...
The Nab experiment will measure the electron-neutrino correlation and Fierz interference term in free neutron beta decay to test Standard Model probe Beyond Physics. Using National Instrument's PXIe-5171 Reconfigurable Oscilloscope module, we have developed a data acquisition system that is not only capable of meeting Nab's specifications, but flexible enough be adapted situ as experimental environment dictates. L1 L2 trigger logic can reconfigured optimize for coincidence event detection at...
The goal of the TRIUMF Ultra-Cold Advanced Neutron (TUCAN) Collaboration is to successfully make an new measurement neutron electric dipole (nEDM) experiment with uncertainty 1 × 10−27 e-cm in 400 days run time, a one order magnitude improvement compared current world’s best. unique using spallation-driven superfluid helium (He-II) source ultracold neutrons (UCN). We are now at stage upgrading UCN produce world-leading densities, He-II cryostat that has undergone cryogenic testing KEK...
The TRIUMF Ultra-Cold Advanced Neutron (TUCAN) collaboration aims at a precision neutron electric dipole moment (nEDM) measurement with an uncertainty of 10 -27 e•cm, which is orderof-magnitude better than the current nEDM upper limit and enables us to test Supersymmetry.To achieve this precision, we are developing new high-intensity ultracold (UCN) source using super-thermal UCN production in superfluid helium (He-II) spectrometer.The development status them reported article.
A family of large bending dipoles has been magnetically measured to support the 10 kW IR-FEL upgrade. This upgrade will allow for a wider wavelength range and an increase in machine energy operate between 80 MeV/c 210 MeV/c. The dipole magnets beam bend 180 degrees over 1 meter radius. requirements these include varying field strengths, horizontal apertures parts 10,000 homogeneity as well setability core integrated field. paper describe process involved measuring achieving requirements.
We report a measurement of two energy-weighted $\ensuremath{\gamma}$ cascade angular distributions from polarized slow neutron capture on the $^{35}\mathrm{Cl}$ nucleus, one parity-odd correlation proportional to $\stackrel{P\vec}{{s}_{n}}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{P\vec}{{k}_{\ensuremath{\gamma}}}$ and parity-even...