S. Riordan
A5056613482- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Atomic and Subatomic Physics Research
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Nuclear physics research studies
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Advanced NMR Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Radiation Therapy and Dosimetry
- Advanced Chemical Physics Studies
- Magnetic confinement fusion research
- Photocathodes and Microchannel Plates
- Medical Imaging Techniques and Applications
- High-pressure geophysics and materials
- Cellular Automata and Applications
- Nuclear reactor physics and engineering
- Radioactive Decay and Measurement Techniques
- Scientific Research and Discoveries
- Crystallography and Radiation Phenomena
Argonne National Laboratory
2017-2024
Stony Brook University
2016-2022
State University of New York
2022
Israel Atomic Energy Commission
2020
The University of Texas at Austin
2020
Soreq Nuclear Research Center
2020
University of Virginia
2009-2019
University of Ljubljana
2018
University of Coimbra
2018
University of Massachusetts Amherst
2011-2016
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...
The u- and d-quark contributions to the elastic nucleon electromagnetic form factors have been determined by using experimental data on G(E)(n), G(M)(n), G(E)(p), G(M)(p). Such a flavor separation of became possible up negative four-momentum transfer squared Q(2) = 3.4 GeV(2) with recent G(E)(n) from Hall A at Jefferson Lab. For above 1 GeV(2), for both u d quark, ratio Pauli Dirac factors, F(2)/F(1), was found be almost constant in sharp contrast behavior F(2)/F(1) proton as whole. Also,...
We studied simultaneously the 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'pn) reactions at Q^2=2 [GeV/c]2 x_B>1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with or neutron recoiling almost back missing momentum, leaving residual A=2 system low excitation energy. These data were used identify two-nucleon short-range correlated pairs deduce their isospin structure as function momentum region where nucleon-nucleon force is expected...
We present deeply virtual ${\ensuremath{\pi}}^{0}$ electroproduction cross-section measurements at ${x}_{B}=0.36$ and three different ${Q}^{2}$ values ranging from 1.5 to $2\text{ }\text{ }{\mathrm{Ge}\mathrm{V}}^{2}$, obtained Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used separate the longitudinal transverse responses. Results demonstrate that cross section dominated by its component and, thus, far asymptotic limit predicted perturbative quantum chromodynamics....
Conceived to host 5 kg of xenon at a pressure 15 bar in the fiducial volume, NEXT- White (NEW) apparatus is currently largest high gas TPC using electroluminescent amplification world. It also 1:2 scale model NEXT-100 detector scheduled start searching for $\beta\beta 0\nu$ decays 136Xe 2019. Both detectors measure energy event plane photomultipliers located behind transparent cathode. They can reconstruct trajectories charged tracks dense with help silicon anode. A sophisticated system,...
The NEXT-White (NEW) detector is currently the largest radio-pure high-pressure xenon gas time projection chamber with electroluminescent readout in world. It has been operating at Laboratorio Subterr'aneo de Canfranc (LSC) since October 2016. This paper describes calibrations performed using 83mKr decays during a long run taken from March to November 2017 (Run II). Krypton are used correct for finite drift-electron lifetime as well dependence of measured energy on event transverse position...
The fundamental theory of the strong interaction-quantum chromodynamics (QCD)—provides foundational framework with which to describe and understand key properties atomic nuclei. A deep understanding explicit role quarks gluons in nuclei remains elusive however, as these effects have thus far been well-disguised by confinement QCD are encapsulated a successful description terms effective hadronic degrees freedom. observation EMC effect has provided an enduring indication for nuclei, points...
We present evidence of non-excimer-based secondary scintillation in gaseous xenon, obtained using both the NEXT-White TPC and a dedicated setup. Detailed comparison with first-principle calculations allows us to assign this mechanism neutral bremsstrahlung (NBrS), process that has been postulated exist xenon largely overlooked. For photon emission below 1000 nm, NBrS yield increases from about 10$^{-2}$ photon/e$^{-}$ cm$^{-1}$ bar$^{-1}$ at pressure-reduced electric field values 50 V above...
We report on the results of E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement twist-3 matrix element ${d}_{2}$ neutron (${d}_{2}^{n}$) was conducted. The quantity ${d}_{2}^{n}$ represents average color Lorentz force struck quark experiences deep inelastic electron scattering event off due to its interaction with hadronizing remnants. This determined from linear combination third moments $^{3}\mathrm{He}$ spin structure functions, ${g}_{1}$ and ${g}_{2}$,...
A bstract Excellent energy resolution is one of the primary advantages electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay ( ββ 0 ν ), which require precise measurements. Using NEXT-White detector, developed by NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show first time that an 1% FWHM can be achieved at 2.6 MeV, establishing present technology best all searches.
We report the first measurement of target-normal single-spin asymmetry in deep-inelastic scattering from inclusive reaction ${^{3}\mathrm{He}}^{\ensuremath{\uparrow}}(e,{e}^{\ensuremath{'}})X$ on a polarized $^{3}\mathrm{He}$ gas target. Assuming time-reversal invariance, this is strictly zero Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using 5.89 GeV electron beam, covers range $1.7<W<2.9\text{...
The proton is composed of quarks and gluons, bound by the most elusive mechanism strong interaction called confinement. In this work, dynamics gluons are investigated using deeply virtual Compton scattering (DVCS): produced a multi-GeV electron, highly photon scatters off which subsequently radiates high energy photon. Similarly to holography, measuring not only magnitude but also phase DVCS amplitude allows perform 3D images internal structure proton. made accessible through...
A bstract The measurement of the internal 222 Rn activity in NEXT-White detector during so-called Run-II period with 136 Xe-depleted xenon is discussed detail, together its implications for double beta decay searches NEXT. measured through alpha production rate induced fiducial volume by and alpha-emitting progeny. specific to be (38.1 ± 2.2 (stat.) 5.9 (syst.)) mBq/m 3 . Radon-induced electrons have also been characterized from 214 Bi daughter ions plating out on cathode time projection...
One of the major goals NEXT-White (NEW) detector is to demonstrate energy resolution that an electroluminescent high pressure xenon TPC can achieve for tracks. For this purpose, calibrations with 137Cs and 232Th sources have been carried out as a part long run taken during most 2017. This paper describes initial results obtained those calibrations, showing excellent linearity extrapolates approximately 1% FWHM at Qββ.
Gaseous time projection chambers (TPC) are a very attractive detector technology for particle tracking. Characterization of both drift velocity and diffusion is great importance to correctly assess their tracking capabilities.
We report on new p(e,e′p)π∘ measurements at the Δ+(1232) resonance low momentum transfer region, where mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The data explore Q2 dependence of resonant quadrupole amplitudes first time indicate that Electric Coulomb converge as Q2→0. amplitude have been extended lowest ever reached, suggest more than half its magnitude attributed in this region. disagree with...
We report the first longitudinal-transverse separation of deeply virtual exclusive ${\ensuremath{\pi}}^{0}$ electroproduction cross section off neutron and coherent deuteron. The corresponding four structure functions $d{\ensuremath{\sigma}}_{L}/dt$, $d{\ensuremath{\sigma}}_{T}/dt$, $d{\ensuremath{\sigma}}_{LT}/dt$, $d{\ensuremath{\sigma}}_{TT}/dt$ are extracted as a function momentum transfer to recoil system at ${Q}^{2}=1.75\text{ }\text{ }{\mathrm{GeV}}^{2}$ ${x}_{B}=0.36$....
A bstract The NEXT experiment aims at searching for the hypothetical neutrinoless double-beta decay from 136 Xe isotope using a high-purity xenon TPC. Efficient discrimination of events through pattern recognition topology primary ionisation tracks is major requirement experiment. However, it limited by diffusion electrons. It known that addition small fraction molecular gas to reduces electron diffusion. On other hand, electroluminescence (EL) yield drops and achievable energy resolution...
High pressure gas time projection chambers (HPGTPCs) are made with a variety of materials, many which still await proper characterization in high noble environments. As HPGTPCs increase size toward ton-scale detectors, assemblies become larger and more complex, creating need for detailed understanding how structural supports voltage insulators behave. This includes identification materials predictable mechanical properties without surface charge accumulation that may lead to field...