Russell Mammei
A5012787759- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
- Quantum, superfluid, helium dynamics
- Radiation Detection and Scintillator Technologies
- Particle physics theoretical and experimental studies
- Particle Detector Development and Performance
- Photocathodes and Microchannel Plates
- Neutrino Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Particle accelerators and beam dynamics
- Diamond and Carbon-based Materials Research
- Plasma Diagnostics and Applications
- Gyrotron and Vacuum Electronics Research
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Advanced NMR Techniques and Applications
- Nuclear physics research studies
- Muon and positron interactions and applications
- Quantum optics and atomic interactions
- Magnetic confinement fusion research
- Electron and X-Ray Spectroscopy Techniques
- Cardiac Structural Anomalies and Repair
- Electrical Contact Performance and Analysis
- Photovoltaic System Optimization Techniques
University of Winnipeg
2015-2024
University of Manitoba
2015-2024
TRIUMF
2019-2023
Campbell Collaboration
2022
Virginia Tech
2005-2019
Thomas Jefferson National Accelerator Facility
2006-2016
ETH Zurich
2005
North Carolina State University
2005
Paul Scherrer Institute
2005
Institut Laue-Langevin
2005
We report a precision measurement of the parity-violating asymmetry $A_{PV}$ in elastic scattering longitudinally polarized electrons from $^{208}$Pb. measure $A_{PV}=550\pm 16 {\rm (stat)}\pm 8\ (syst)}$ parts per billion, leading to an extraction neutral weak form factor $F_W(Q^2 = 0.00616\ GeV}^2) 0.368 \pm 0.013$. Combined with our previous measurement, extracted neutron skin thickness is $R_n-R_p=0.283 0.071$~fm. The result also yields first significant direct interior density...
We report a precise measurement of the parity-violating (PV) asymmetry A_{PV} in elastic scattering longitudinally polarized electrons from ^{48}Ca. measure A_{PV}=2668±106(stat)±40(syst) parts per billion, leading to an extraction neutral weak form factor F_{W}(q=0.8733 fm^{-1})=0.1304±0.0052(stat)±0.0020(syst) and charge minus F_{ch}-F_{W}=0.0277±0.0055. The resulting neutron skin thickness R_{n}-R_{p}=0.121±0.026(exp)±0.024(model) fm is relatively thin yet consistent with many model...
The Polarized Electrons for Positrons experiment at the injector of Continuous Electron Beam Accelerator Facility has demonstrated first time efficient transfer polarization from electrons to positrons produced by polarized bremsstrahlung radiation induced a electron beam in high-Z target. Positron up 82% have been measured an initial momentum 8.19 MeV/c, limited only polarization. This technique extends positron capabilities GeV MeV beams, and opens access physics wide community.
A new measurement of the neutron $β$-decay asymmetry $A_0$ has been carried out by UCNA collaboration using polarized ultracold neutrons (UCN) from solid deuterium UCN source at Los Alamos Neutron Science Center (LANSCE). Improvements in experiment have led to reductions both statistical and systematic uncertainties leading $A_0 = -0.11954(55)_{\rm stat.}(98)_{\rm syst.}$, corresponding ratio axial-vector vector coupling $λ\equiv g_A/g_V -1.2756(30)$.
In this paper, we describe the performance of Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements cold flux, very low energy production rate, and UCN rates density at exit from biological shield are presented compared to Monte Carlo predictions. The compare well with predictions code MCNPX agree our custom code. source is shown perform as modeled. maximum delivered 52(9) UCN/cc a solid deuterium volume ∼1500 cm3.
A precise measurement of the neutron decay β asymmetry A₀ has been carried out using polarized ultracold neutrons from pulsed spallation source at Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report = -0.119 66±0.000 89{-0.001 40}{+0.001 23}, which determine ratio axial-vector to vector weak coupling nucleon g{A}/g{V}=-1.275 90{-0.004 45}{+0.004 09}.
We present a detailed report of measurement the neutron $\beta$-asymmetry parameter $A_0$, parity-violating angular correlation between spin and decay electron momentum, performed with polarized ultracold neutrons (UCN). UCN were extracted from pulsed spallation solid deuterium source via transport through 7-T magnetic field. The then transported an adiabatic-fast-passage spin-flipper field region, prior to storage in cylindrical volume situated within 1-T $2 \times 2\pi$ solenoidal...
It has been proposed recently that a previously unobserved neutron decay branch to dark matter particle ($\ensuremath{\chi}$) could account for the discrepancy in lifetime observed experiments use two different measurement techniques. One of possible final states discussed includes single $\ensuremath{\chi}$ along with an ${e}^{+}{e}^{\ensuremath{-}}$ pair. We data from UCNA (Ultracold Neutron Asymmetry) experiment set limits on this channel. Coincident electron-like events are detected...
We installed a source for ultracold neutrons at new, dedicated spallation target TRIUMF. The was originally developed in Japan and uses superfluid-helium converter cooled to 0.9$\,$K. During an extensive test campaign November 2017, we extracted up 325000 after one-minute irradiation of the target, over three times more than previously achieved with this source. corresponding ultracold-neutron density whole production guide volume is 5.3$\,$cm$^{-3}$. storage lifetime initially 37$\,$s...
We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in elastic scattering 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, ^{208}Pb at very forward angles where most detailed theoretical calculations have been performed. The first measurements A_{n} for ^{40}Ca ^{48}Ca are found to be similar that consistent with expectations thus demonstrating validity nuclei Z≤20. also two new momentum transfers (Q^{2}) extending previous measurement. Our data...
Two ${\mathrm{K}}_{2}\mathrm{CsSb}$ photocathodes were manufactured at Brookhaven National Lab and delivered to Jefferson within a compact vacuum apparatus pressure $\ensuremath{\sim}{10}^{\ensuremath{-}11}\text{ }\text{ }\mathrm{Torr}$. These evaluated using dc high voltage photogun biased voltages up 200 kV, illuminated with laser light wavelengths 440 or 532 nm, generate electron beams currents 20 mA. Some conditions produced exceptionally large photocathode charge lifetimes, without...
The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the $\beta$-decay asymmetry parameter, $A_0$, for free neutron decay. In experiment, polarized ultracold neutrons are transported into a decay trap, and their electrons detected with $\approx 4\pi$ acceptance two detector packages which provide position energy reconstruction. also has sensitivity $b_{n}$, Fierz interference term in rate. this work, we determine $b_{n}$ from dependence of $A_0$ using data taken during...
We report the first measurement of an angular correlation parameter in neutron $\ensuremath{\beta}$ decay using polarized ultracold neutrons (UCN). utilize UCN with energies below about 200 neV, which we guide and store for $\ensuremath{\sim}30\text{ }\text{ }\mathrm{s}$ a Cu volume. The interaction magnetic dipole moment static 7 T field external to volume provides 420 neV potential energy barrier spin state parallel field, polarizing before they pass through adiabatic fast passage flipper...
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,...
Precision measurements of free-neutron β decay have been used to precisely constrain our understanding the weak interaction. However, neutron Fierz interference term bn, which is particularly sensitive beyond-standard-model tensor currents at TeV scale, has thus far eluded measurement. Here we report first direct constraints on this term, finding bn=0.067±0.005stat+0.090−0.061sys, consistent with standard model. The uncertainty dominated by absolute energy reconstruction and linearity...
The field emission characteristics of niobium electrodes were compared to those stainless steel using a DC high voltage test apparatus. A total eight evaluated: two 304 polished mirrorlike finish with diamond grit and six (two single-crystal, large-grain, fine-grain) that chemically buffered-chemical acid solution. Upon the first application voltage, best large-grain single-crystal performed better than electrodes, exhibiting less at comparable strength. In all cases, from (stainless and/or...
The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component this experiment an adiabatic fast passage spin flipper capable efficient operation ambient magnetic fields on order 1 T. requirement that it operate high field necessitated construction based, for first time, birdcage resonator. design, construction, and initial testing prior to its use with UCN during 2007 run cycle Los Alamos...
Delta-Rice is an HDF5 (The HDF Group et al., 2020) filter plugin that was developed to compress digitized detector signals recorded by the Nab experiment (Fry 2019), a fundamental neutron physics experiment.This two-step process where incoming data passed through pre-processing and then compressed with Rice coding.A routine for determining optimal dataset provided along example GPU deployment.When applied collected acquisition system, this method produced output files 29% their initial size,...
The alkali species Cs and K were codeposited using an effusion source, onto relatively thick layers of Sb (50 nm to ∼7 μm) grown on GaAs Ta substrates inside a vacuum chamber that was baked not-vented, also vented with clean dry nitrogen but not rebaked. characteristics the films, including sticking probability, surface roughness, grain size, crystal properties very different for these conditions, yet comparable values photocathode yield [or quantum efficiency (QE)] at 284 V obtained...