A5041058876- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Quantum, superfluid, helium dynamics
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- Nuclear physics research studies
- Particle physics theoretical and experimental studies
- Radioactive Decay and Measurement Techniques
- Advanced NMR Techniques and Applications
- Dark Matter and Cosmic Phenomena
- Radiation Therapy and Dosimetry
- Cold Atom Physics and Bose-Einstein Condensates
- Nuclear reactor physics and engineering
- Quantum Chromodynamics and Particle Interactions
- Particle accelerators and beam dynamics
- Radioactivity and Radon Measurements
- Atomic and Molecular Physics
- Geophysical Methods and Applications
- Particle Detector Development and Performance
- Cold Fusion and Nuclear Reactions
- Methane Hydrates and Related Phenomena
- X-ray Spectroscopy and Fluorescence Analysis
- Radioactive contamination and transfer
- Gyrotron and Vacuum Electronics Research
- Particle Accelerators and Free-Electron Lasers
Tulane University
2013-2024
National Institute of Standards and Technology
1996-2014
University of Michigan–Ann Arbor
2010
Harvard University
1999-2005
European Commission
2005
Oak Ridge National Laboratory
2005
University of Tennessee at Knoxville
2005
Material (Belgium)
2005
Indiana University Bloomington
2005
DePauw University
2005
The most precise determination of the neutron lifetime using beam method was completed in 2005 and reported a result $\tau_n = (886.3 \pm 1.2 [\textrm{stat}] 3.2 [\textrm{syst}])$ s. dominant uncertainties were attributed to absolute fluence (2.7 s). measured with monitor that counted neutron-induced charged particles from absorption thin, well-characterized 6Li deposit. detection efficiency calculated areal density deposit, detector solid angle, evaluated nuclear data file, ENDF/B-VI...
The decay of the free neutron into a proton, electron, and antineutrino is prototype semileptonic weak simplest example nuclear beta decay. It played key role in early Universe as it determined ratio neutrons to protons during era primordial light element nucleosynthesis. Neutron physically related important processes solar physics neutrino detection. mean lifetime has been subject more than 20 major experiments done, using variety methods, between 1950 present. most precise recent...
A measurement of the neutron lifetime ${\ensuremath{\tau}}_{n}$ performed by absolute counting in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto silicon detector held at high potential counted with nearly unit efficiency. The device an efficiency inversely proportional to velocity, which cancels dwell time beam trap. result is...
We report the first result for electron-antineutrino angular correlation ($a$ coefficient) in free neutron $\ensuremath{\beta}$ decay from aCORN experiment. uses a novel method which $a$ coefficient is proportional to an asymmetry proton time of flight events where electron and recoil are detected delayed coincidence. Data presented 15 month run at NIST Center Neutron Research. obtained...
The aCORN experiment measures the neutron-decay electron-antineutrino correlation ($a$ coefficient) using a novel method based on an asymmetry in proton time-of-flight for events where beta electron and recoil are detected delayed coincidence. We report data analysis result from second run at NIST Center Neutron Research, high-flux cold neutron beam new NG-C guide end position:...
We report the results of an improved determination triple correlation $D P \cdot(p_{e}\times p_{\nu})$ that can be used to limit possible time-reversal invariance in beta decay polarized neutrons and constrain extensions Standard Model. Our result is $D=(-0.96\pm 1.89 (stat)\pm 1.01 (sys))\times 10^{-4}$. The corresponding phase between g_A g_V $\phi_{AV} = 180.013^\circ\pm0.028^\circ$ (68 % confidence level). This represents most sensitive measurement D decay.
The standard model predicts that, in addition to a proton, an electron, and antineutrino, continuous spectrum of photons is emitted the β decay free neutron. We report on RDK II experiment which measured photon using two different detector arrays. An annular array bismuth germanium oxide scintillators detected from 14 782 keV. spectral shape was consistent with theory, we determined branching ratio 0.00335±0.00005[stat]±0.00015[syst]. A second large area avalanche photodiodes directly 0.4...
We have measured the electron-capture decay branch of $^{100}\mathrm{Tc}$ to be (1.8\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$%, from which we deduce logft=4.${45}_{\mathrm{\ensuremath{-}}0.30}^{+0.18}$. This indicates that a two-step process connecting only ground states $^{100}\mathrm{\ensuremath{-}}^{100}$Tc${\mathrm{\ensuremath{-}}}^{100}$Ru can account for 2\ensuremath{\nu} double-\ensuremath{\beta}-decay rate $^{100}\mathrm{Mo}$.
Background: Time-reversal-invariance violation, or equivalently CP may explain the observed cosmological baryon asymmetry as well signal physics beyond Standard Model. In decay of polarized neutrons, triple correlation D<J_{n}>\cdot(p_{e}\timesp_{\nu}) is a parity-even, time-reversal- odd observable that uniquely sensitive to relative phase axial-vector amplitude with respect vector amplitude. The also possible contributions from scalar and tensor amplitudes. Final-state effects contribute D...
We report a new measurement of the neutron decay lifetime by absolute counting in-beam neutrons and their protons. Protons were confined in quasi-Penning trap counted with silicon detector. The beam fluence was measured capture thin 6LiF foil detector known efficiency. combination these simultaneous measurements gives lifetime: tau(n)=(886.8+/-1.2[stat]+/-3.2[syst]) s. systematic uncertainty is dominated uncertainties mass deposit 6Li(n,t) cross section. This most precise to date using an method.
Free neutron decay is a fundamental process in particle and nuclear physics. It the prototype for beta other semileptonic weak decays. Neutron played key role formation of light elements early universe. The precise value mean lifetime, about 15 min, has been subject many experiments over past 70 years. two main experimental methods, beam method ultracold storage method, give average values lifetime that currently differ by 8.7 s (4 standard deviations), serious discrepancy. physics decay,...
We describe an experiment that has set new limits on the time reversal invariance violating D coefficient in neutron beta-decay. The emiT measured angular correlation J . p_e x p_p using octagonal symmetry optimizes electron-proton coincidence rates. result is D=[-0.6+/-1.2(stat)+/-0.5(syst)]x10^(-3). This improves constraints phase of g_A/g_V and contributions to T violation due leptoquarks. paper presents details experiment, data analysis, investigation systematic effects.
The theory of quantum electrodynamics predicts that the $\ensuremath{\beta}$ decay neutron into a proton, electron, and antineutrino is accompanied by continuous spectrum emitted photons described as inner bremsstrahlung. While this phenomenon has been observed in nuclear electron-capture for many years, it only recently free-neutron decay. We present detailed discussion an experiment which radiative mode free was observed. In experiment, branching ratio rare determined recording were...
A precise value of the neutron lifetime is important in several areas physics, including determinations quark-mixing matrix element │Vud│, related tests Standard Model, and predictions light abundances Big Bang Nucleosynthesis models. We report progress on a new measurement utilizing cold beam technique. Several experimental improvements both proton counting that have been developed over last decade are presented. This effort should yield final uncertainty 1 s with an improved understanding...
Three-dimensional magnetic confinement of neutrons is reported. Neutrons are loaded into an Ioffe-type superconducting trap through inelastic scattering cold with 4He. Scattered sufficiently low energy and in the appropriate spin state confined by field until they decay. The electron resulting from neutron decay produces scintillations liquid helium bath that results a pulse extreme ultraviolet light. This light frequency downconverted to visible detected. Results presented which 500 +/- 155...
We present the results of two separate measurements half-life ${}^{44}\mathrm{Ti}$ relative to those ${}^{22}\mathrm{Na}$ and ${}^{207}\mathrm{Bi},$ respectively. By comparing numbers 1157-keV \ensuremath{\gamma} rays from 1274-keV observed a mixed source over period approximately 2 yr, we determined be $61.5\ifmmode\pm\else\textpm\fi{}1.0\mathrm{yr}.$ From an 1-yr-long study another source, where compared 1064-keV $62\ifmmode\pm\else\textpm\fi{}5\mathrm{yr}.$ these results, have obtained...
We report the first measurement of low-energy neutron-(3)He incoherent scattering length using neutron interferometry: b_{i};{'} = (-2.512 +/- 0.012 stat 0.014 syst) fm. This is in good agreement with a recent calculation AV18 + 3N potential. The lengths are important for testing and developing nuclear potential models that include three-nucleon forces, effective field theories few-body systems, measurements quantum excitations liquid helium. work demonstrates use polarized target interferometer.
We respond to issues raised by Serebrov et al. in a recent paper regarding systematic effects the beam neutron lifetime experiment performed at NIST. show that these were considered original analyses and our corrections uncertainties appropriate. point out some misunderstandings analysis of None lead us alter value reported.