L. J. Kaufman
A5032493725- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Quantum Chromodynamics and Particle Interactions
- Nuclear physics research studies
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- High-Energy Particle Collisions Research
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Scientific Research and Discoveries
- Electron and X-Ray Spectroscopy Techniques
- Radiation Therapy and Dosimetry
- Atmospheric Ozone and Climate
- Medical Imaging Techniques and Applications
- Nuclear reactor physics and engineering
- Superconducting Materials and Applications
- African Education and Politics
- Advanced NMR Techniques and Applications
- Solar and Space Plasma Dynamics
- Atomic and Molecular Physics
SLAC National Accelerator Laboratory
2018-2023
Indiana University Bloomington
2014-2023
University of Massachusetts Amherst
2008-2022
William & Mary
2006-2020
Williams (United States)
2020
Indiana University
2018
Stanford University
2018
Amherst College
2009-2015
Amridge University
2015
University of Maryland, College Park
2008-2010
The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest all low-energy neutrino couplings. This mode interaction offers new opportunities to study properties and leads a miniaturization detector size, with potential technological applications. We observed this process at 6.7σ confidence level, using low-background, 14.6-kilogram CsI[Na] scintillator exposed emissions from Spallation Neutron...
The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where proton is knocked-out of the with high momentum transfer missing momentum, show that 12C neutron-proton pairs are nearly twenty times as prevalent proton-proton and, by inference, neutron-neutron This difference between types due to nature strong force has implications for understanding cold dense nuclear systems such neutron stars.
We report on a search for neutrinoless double-beta decay of $^{136}$Xe with EXO-200. No signal is observed an exposure 32.5 kg-yr, background ~1.5 x 10^{-3} /(kg yr keV) in the $\pm 1\sigma$ region interest. This sets lower limit half-life $T_{1/2}^{0\nu\beta\beta}$($^{136}$Xe) > 1.6 10$^{25}$ (90% CL), corresponding to effective Majorana masses less than 140-380 meV, depending matrix element calculation.
A search for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{136}$Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between $0\nu\beta\beta$ and background events. Relative previous analyses, signal detection efficiency has been raised from 80.8% 96.4$\pm$3.0% energy resolution of detector at Q-value improved $\sigma/E=1.23\%$ $1.15\pm0.02\%$ upgraded detector. Accounting new data, median 90% confidence level half-life sensitivity this analysis...
Results from a search for neutrinoless double-beta decay (0νββ) of ^{136}Xe are presented using the first year data taken with upgraded EXO-200 detector. Relative to previous searches by EXO-200, energy resolution detector has been improved σ/E=1.23%, electric field in drift region raised 50%, and system suppress radon volume between cryostat lead shielding implemented. In addition, analysis techniques that improve topological discrimination 0νββ background events have developed....
We report the first measurement of coherent elastic neutrino-nucleus scattering (CEvNS) on argon using a liquid detector at Oak Ridge National Laboratory Spallation Neutron Source. Two independent analyses prefer CEvNS over background-only null hypothesis with greater than $3\ensuremath{\sigma}$ significance. The measured cross section, averaged incident neutrino flux, is $(2.2\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}39}\text{ }\text{...
We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) 10(syst)] x 10(-9), leading to determination weak mixing angle sin2(thetaW(eff) 0.2397 0.0010(stat) 0.0008(syst), evaluated at Q2 0.026 GeV2. Combining this result with measurements Z0 pole, running is observed over 6sigma significance. The sets constraints new physics effects TeV scale.
We report new measurements of the parity-violating asymmetry ${A}_{\mathrm{PV}}$ in elastic scattering 3 GeV electrons off hydrogen and $^{4}\mathrm{He}$ targets with $⟨{\ensuremath{\theta}}_{\mathrm{lab}}⟩\ensuremath{\approx}6.0\ifmmode^\circ\else\textdegree\fi{}$. The result is ${A}_{\mathrm{PV}}=\mathbf{(}+6.40\ifmmode\pm\else\textpm\fi{}0.23(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{syst})\mathbf{)}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$....
We report the observation of two-neutrino double-beta decay in Xe-136 with T_1/2 = 2.11 +- 0.04 (stat.) 0.21 (sys.) x 10^21 yr. This second order process, predicted by Standard Model, has been observed for several nuclei but not Xe-136. The rate provides new input to matrix element calculations and search more interesting neutrino-less decay, most sensitive probe existence Majorana particles measurement neutrino mass scale.
We report on measurements of the neutron spin asymmetries An1,2 and polarized structure functions gn1,2 at three kinematics in deep inelastic region, with x=0.33, 0.47, 0.60 Q2=2.7, 3.5, 4.8(GeV∕c)2, respectively. These were performed using a 5.7GeV longitudinally electron beam 3He target. The results for An1 gn1 x=0.33 are consistent previous world data and, two higher-x points, have improved precision by about an order magnitude. new show zero crossing around x=0.47 value x=0.60 is...
We present the first measurements of $\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}ep\ensuremath{\gamma}$ cross section in deeply virtual Compton scattering (DVCS) regime and valence quark region. The ${Q}^{2}$ dependence (from 1.5 to $2.3\text{ }\text{ }{\mathrm{GeV}}^{2}$) helicity-dependent indicates twist-2 dominance DVCS, proving that generalized parton distributions (GPDs) are accessible experiment at moderate ${Q}^{2}$. helicity-independent is also measured...
We report on an improved measurement of the $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ half-life ${}^{136}$Xe performed by EXO-200. The use a large and homogeneous time-projection chamber allows for precise estimate fiducial mass used measurement, resulting in small systematic uncertainty. also discuss detail data-analysis methods double-$\ensuremath{\beta}$ decay searches with EXO-200, while emphasizing those directly related to present measurement. is found be...
We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2=2 (GeV/c)2, xB=1.2, in an (e, e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing momentum greater than Fermi of nucleons nucleus far delta excitation, short-range nucleon-nucleon correlations are predicted dominate reaction. For (9.5+/-2)% events, recoiling partner proton was observed back-to-back vector, experimental signature correlations.
EXO-200 is an experiment designed to search for double beta decay of $^{136}$Xe with a single-phase, liquid xenon detector. It uses active mass 110 kg enriched 80.6% in the isotope 136 ultra-low background time projection chamber capable simultaneous detection ionization and scintillation. This paper describes detector particular attention most innovative aspects design that revolve around reduction backgrounds, efficient use expensive isotopically xenon, optimization energy resolution...
The next-generation Enriched Xenon Observatory (nEXO) is a proposed experiment to search for neutrinoless double beta ($0\nu\beta\beta$) decay in $^{136}$Xe with target half-life sensitivity of approximately $10^{28}$ years using $5\times10^3$ kg isotopically enriched liquid-xenon time projection chamber. This improvement two orders magnitude over current limits obtained by significant increase the mass, monolithic and homogeneous configuration active medium, multi-parameter measurements...
Abstract The nEXO neutrinoless double beta (0 νββ ) decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon search for the in 136 Xe. Progress detector design, paired with higher fidelity its simulation an advanced data analysis, based on one used final results EXO-200, produce sensitivity prediction that exceeds half-life 10 28 years. Specifically, improvements have been made understanding production scintillation photons charge as...
The projected performance and detector configuration of nEXO are described in this pre-Conceptual Design Report (pCDR). is a tonne-scale neutrinoless double beta ($0νββ$) decay search $^{136}$Xe, based on the ultra-low background liquid xenon technology validated by EXO-200. With $\simeq$ 5000 kg enriched to 90% isotope 136, has half-life sensitivity approximately $10^{28}$ years. This represents an improvement about two orders magnitude with respect current results. Based experience gained...
We have measured the parity-violating electroweak asymmetry in elastic scattering of polarized electrons from 4He at an average angle <theta(lab)> = 5.7 degrees and a four-momentum transfer Q2 0.091 GeV2 . From these data, for first time, strange electric form factor nucleon G(E)s can be isolated. The A(PV) (6.72 +/- 0.84(stat) 0.21(syst) x 10(-6) yields value -0.038 0.042(stat) 0.010(syst), consistent with zero.
The present experiment exploits the interference between Deeply Virtual Compton Scattering (DVCS) and Bethe-Heitler processes to extract imaginary part of DVCS amplitudes on neutron deuteron from helicity-dependent D$({\vec e},e'\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ $x_B$=0.36. We a linear combination generalized parton distributions (GPDs) particularly sensitive $E_q$, least constrained GPD. A model dependent constraint contribution up down quarks nucleon spin is deduced.
We report the most precise measurement to date of a parity-violating asymmetry in elastic electron-proton scattering. The was carried out with beam energy 3.03 GeV and scattering angle =6 degrees, result A_PV = -1.14 +/- 0.24 (stat) 0.06 (syst) parts per million. From this we extract, at Q^2 0.099 GeV^2, strange form factor combination G_E^s + 0.080 G_M^s 0.030 0.025 0.006 0.012 (FF) where first two errors are experimental last error is due uncertainty neutron electromagnetic factor. This...
We have measured the neutron spin asymmetry A(n)(1) with high precision at three kinematics in deep inelastic region x=0.33, 0.47, and 0.60, Q(2)=2.7, 3.5, 4.8 (GeV/c)(2), respectively. Our results unambiguously show, for first time, that crosses zero around x=0.47 becomes significantly positive x=0.60. Combined world proton data, polarized quark distributions were extracted. results, general, agree relativistic constituent models perturbative quantum chromodynamics (PQCD) analyses based on...
The electric form factor of the neutron was determined from studies reaction ${}^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{e},{e}^{\ensuremath{'}}n)pp$ in quasielastic kinematics Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a target which nuclear polarization oriented perpendicular to momentum transfer. detected magnetic spectrometer coincidence with neutrons that registered large-solid-angle detector. More than...
We present final results on the photon electroproduction ($\vec{e}p\rightarrow ep\gamma$) cross section in deeply virtual Compton scattering (DVCS) regime and valence quark region from Jefferson Lab experiment E00-110. Results an analysis of a subset these data were published before, but has been improved which is described here at length, together with details experimental setup. Furthermore, additional have analyzed resulting sections new kinematic settings, for total 588 bins. $Q^2$-...