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Brian Raue (Florida International University)9/12/17, 8:40 AMSince the discovery of the discrepancy between Rosenbluth and polarization-transfer measurements of the proton form-factor ratio $G_E/G_M$ there has been a renewed interest in measuring contributions to the elastic cross section from two-photon exchange (TPE). Three recent experiments conducted at CLAS, VEPP-3, and OLYMPUS directly determined the real part of the TPE amplitude by measuring the...Go to contribution page
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Andrei Afanasev (GWU)9/12/17, 9:15 AM
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Peter Blunden (University of Manitoba)9/12/17, 9:50 AMIn this talk I will give an overview of recent progress in theoretical calculations of two-photon exchange (TPE) effects in elastic electron-proton scattering. This will include a survey of existing models and theoretical frameworks. TPE effects are relevant for extractions of proton form factors at high $Q^2$, and of the proton radius at low $Q^2$. Recent experiments to directly measure hard...Go to contribution page
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Volker Burkert (Jefferson Lab)9/12/17, 10:35 AM
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Larry cardman (Jefferson Lab)9/12/17, 11:20 AMOral ContributionThe Polarized Electrons for Polarized Positrons (PEPPo) experiment at the injector of the Continuous Electron Beam Accelerator Facility demonstrated for the first time the efficient transfer of polarization from electrons to positrons via a two-step process: polarized bremsstrahlung radiation is induced by a polarized electron beam in a high-Z target; and then the polarized bremsstrahlung...Go to contribution page
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Maxime DeFurne9/12/17, 11:50 AM
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Mikhail Yurov (UVA)9/12/17, 1:25 PMTwo experimental techniques, Rosenbluth separation and recoil polarization transfer, used to extract proton's electromagnetic form factors ratio $\frac{G_E}{G_M}$ yield markedly different results. Modern theoretical calculations suggest that two-photon exchange (TPE) might be responsible for the observed discrepancy and that it is $\varepsilon$ dependent. Jefferson Lab Experiment E05-017 was...Go to contribution page
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Francois-Xavier Girod (JLab)9/12/17, 1:50 PMThe exclusive electroproduction of a hard photon off a nucleon $eN\rightarrow eN\gamma$ provides three-dimensional information on the nucleon structure. This reaction proceeds via the Bethe-Heitler (BH) process (with the photon emitted by the electron), and the Deeply Virtual Compton Scattering (DVCS) process (with the photon emitted by the proton). BH and DVCS are indistinguishable, and...Go to contribution page
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Axel Schmidt (MIT)9/12/17, 2:15 PMThe discrepancy between polarized and unpolarized measurements of the proton's electromagnetic form factors is striking, and suggests that two-photon exchange (TPE) may be playing a larger role in elastic electron-proton scattering than is estimated in standard radiative corrections formulae. While TPE is difficult to calculate in a model-independent way, it can be determined experimentally...Go to contribution page
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Ferdinand Willeke (Brookhaven National Lab)9/12/17, 3:00 PM
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Yves Roblin (Jefferson Lab)9/12/17, 3:30 PMWe will discuss the possibility of using CEBAF as a positron machine. After a review of the current machine capabilities, we will examine one particular scenario for generating, accelerating and transporting positrons in CEBAF. Modifications to the existing CEBAF machine will be discussed as well as expected performance and impact on the regular program.Go to contribution page
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Michael Tiefenback (Jefferson Lab)9/12/17, 4:00 PMOperation of CEBAF with positrons using the standard electron beam direction (clockwise as viewed from above) requires inverting the polarity of the recirculation arc and Spreader/Recombiner dipoles. Retaining the focusing optics used for electrons requires inverting the quadrupole gradients. The hardware readily supports reversed polarity, and no observations are known to suggest any change...Go to contribution page
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Michael Tiefenback (JLab)9/12/17, 4:30 PMThe CEBAF accelerator has a demonstrated capacity for delivery of electron current to Hall B at the ~100 nA level, on par with the current anticipated for future positron beams. However, machine configuration requires macropulse current levels of a few micro-Amperes due to limited sensitivity of many installed diagnostics. Informed by this operational experience, we outline a set of...Go to contribution page
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David Gaskell (Jefferson Lab)9/12/17, 5:00 PM
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Stefan Schmitt (DESY)9/13/17, 8:30 AMStructure functions and parton densities determined in ep collisions at HERA are reviewed. At HERA, about 0.5 fb-1 of data were recorded at a centre-of-mass energy of about 320 GeV by each of the two collider experiments H1 and ZEUS. The data samples are about equally shared between operation with e+p and e-p beams. In e+p collisions further small...Go to contribution page
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Jeff Owens (Florida State University)9/13/17, 9:10 AMIn order to better understand the behavior of parton distribution functions in x and Q, it is necessary to be able to separate the contributions from various flavors. Such flavor differentiation can be greatly assisted by charged current deep inelastic scattering. The status of flavor differentiation will be discussed and some useful examples utilizing charged current interactions will be given.Go to contribution page
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Charlotte Van Hulse (University of the Basque Country UPV/EHU)9/13/17, 9:40 AMThe study of the nucleon spin structure has been approached from two complementary perspectives. From the one hand, generalized parton distributions (GPDs) give information about the distribution of quarks and gluons inside the nucleon as a function of the fraction of their longitudinal momentum with respect to the longitudinal nucleon momentum and as a function of their transverse...Go to contribution page
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Tanja Horn (Catholic University of America)9/13/17, 10:40 AM
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Jae Nam9/13/17, 11:10 AM
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Michael Murray (University of Kansas)9/13/17, 11:40 AMOral ContributionThe unprecedented energies, luminosities and experimental capabilities of the LHC have given physicists opportunities to search for new physics over a very wide mass range using photon induced reactions. This talk will summarize recent LHC results on photon-photon, photon proton and photon-proton reactions at both the electroweak and QCD scales. These results will be placed in the context of...Go to contribution page
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Atsuo Kawasuso (QST)9/13/17, 1:30 PMOral ContributionPositrons emitted from radioisotopes are longitudinally spin-polarized due to parity non-conservation in the weak interaction. In 1960's, the angular correlation of annihilation radiation measurement with spin-polarized positrons was demonstrated to be useful in studying the ferromagnetic band structures. In 1982, the first experiment on surface ferromagnetism with spin-polarized positron beam...Go to contribution page
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Allen Mills, Jr. (University of California Riverside)9/13/17, 2:05 PMOne goal of the JPos-17 International Workshop on Physics with Positrons is to ascertain whether it would be a good idea to expand the mission of the Thomas Jefferson National Accelerator Facility to include science with low energy (i.e. “slow”) spin polarized positrons. It is probably true that experimentation with slow positrons would potentially have wide-ranging benefits comparable to...Go to contribution page
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Stephen Benson (Jefferson Lab)9/13/17, 3:05 PMThough there are many applications of low energy positrons, many experiments are source limited. Using the LERF accelerator at the Thomas Jefferson National Accelerator Facility, it is possible to produce a high brightness source of very low-energy positrons. The accelerator requirements are well within the capabilities of the installed hardware. The accelerator can easily produce 50 kW of...Go to contribution page
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Andreas Wagner (Helmholtz-Zentrum Dresden-Rossendorf)9/13/17, 3:40 PMThe Helmholtz-Center at Dresden-Rossendorf operates several user beamlines for materials research using positron annihilation energy and lifetime spectroscopy. Two beamlines are being operated at a superconducting electron linear accelerator [1] producing hard X-rays from electron-bremsstrahlung and in turn generating positrons from pair production. Both installations employ bunched...Go to contribution page
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Toshio HYODO (Slow positron applications at Slow Positron Facility of Institute of Materials Structure Science, KEK)9/13/17, 4:15 PMPositron ApplicationsSlow Positron Facility at KEK (High Energy Accelerator Research Organization) is a user dedicated facility with an energy-tunable (0.1 - 35 keV) slow positron beam created by a dedicated 50MeV linac [1]. It operates in a short pulse (width 1-12 ns, variable, \5\times 10 ^6\ e\^+\/s) and a long pulse (width 1.2 \mu s, \5\times 10 ^7\ e\^+\/s) modes of 50 Hz. High energy positrons from pair...Go to contribution page
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Nagendra Nath MONDAL (Techno India Batanagar (Techno India Group))9/13/17, 4:50 PM
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Rolland Johnson (Muons, Inc.)9/13/17, 5:20 PM
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Bogdan Wojtsekhowski (Jefferson Lab)9/14/17, 8:30 AM
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Sonny Mantry9/14/17, 8:50 AM
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Seamus Riordan (Stony Brook University)9/14/17, 9:25 AMTest of the Standard ModelWeak neutral current interactions with charged leptons have offered unique opportunities to study novel aspects of hadronic structure and search for physics beyond the standard model. These studies in the medium energy community have been primarily through parity-violating processes with electron beams, but with the possibility of polarized positron beams, new and complementary...Go to contribution page
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Paolo Valente (INFN Rome)9/14/17, 10:10 AMDark Matter elusiveness could be explained by speculating that it lives in a separate sector with respect to the Standard Model (SM) and that interacts with it only by means of messengers. The simplest model foresees just one messenger: a possibly massive vector boson given by a new U(1) symmetry. This mediator can faintly mix with the photon and, hence, interact with SM charged particles,...Go to contribution page
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Luca Marsicano (INFN Genova)9/14/17, 10:45 AMThe interest in the Dark Photon (A' or U) has recently grown, since it could act as a light mediator to a new sector of Dark Matter particles. In this paradigm, the electron-positron annihilation can rarely produce a $\gamma $ U couple. Various experiments (e.g. PADME@LNF, Adv. High Energy Phys. 2014:959802; VEPP-3, arXiv:1207.5089[hep-ex]) have been proposed to detect this process using ...Go to contribution page
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Nathan Sherrill (Indiana University Bloomington)9/14/17, 11:10 AMProposed theories beyond the Standard Model (SM) can support the breaking of Lorentz and CPT symmetry. Searches for violations of these symmetries are often performed within the framework of the Standard Model Extension (SME), the most general effective field theory parametrizing CPT and Lorentz violation. The breaking of CPT and Lorentz symmetries in the SME is characterized by coefficients...Go to contribution page
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Varghese Anto Chirayath (Department of Physics, University of Texas at Arlington, 76019)9/14/17, 1:00 PMWe discuss our recent report on the direct observation of a low-energy Auger electron emission process initiated by the creation of a deep valence hole in single layer graphene through positron annihilation. Here, an electron from a higher energy level in the valence band fills the valence hole created by positron-electron annihilation. The energy released because of this relaxation is...Go to contribution page
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Jan Kuriplach (Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic)9/14/17, 1:25 PMPositronium can be very helpful when studying the electronic structure of materials. Indeed, the recent experiment [1], where the Ps emission from a copper (110) surface was examined, allowed for the precise determination of the electron chemical potential of copper by means of measuring the Ps affinity. This affinity ($A_{Ps}$) [1] is defined formally via the electron ($\Phi_-$) and positron...Go to contribution page
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J. David Van Horn (University of Missouri-Kansas City)9/14/17, 1:50 PMAsymmetry is a basic property found at multiple scales in the universe [1]. Asymmetric molecular interactions are fundamental to the operation of biological systems in both signaling and structural roles. Other aspects asymmetry are observed and useful in many areas of science and engineering and have been studied since the discovery of chirality in tartrate salts [2]. The observation of...Go to contribution page
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Ali R. Koymen (University of Texas at Arlington)9/14/17, 2:15 PMThe ability of positrons to create polarized core holes stems from the fact that the annihilation rate for spin singlet collisions is 1115 times faster than for spin triplet collisions and thus ~558 times faster with an electron of opposite spin. It is therefore possible to use the inherent polarization of positron beams to create polarized core holes with a net polarization approximately...Go to contribution page
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Fanglei Lin (Jefferson Lab)9/15/17, 8:30 AMBoth polarized and unpolarized positron beams with an energy range from a few eV to hundreds of GeV have diverse applications in medicine, material science and nuclear physics. In many cases, they are the unique tools for the study of the physical world. However, the creation of polarized positrons with sufficient intensity is particularly challenging. We propose a dedicated scheme to generate...Go to contribution page
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Jan Bernauer (MIT)9/15/17, 9:10 AMOne of the puzzles of the proton form factor is the difference between determinations of the form factor ratio using unpolarized and polarized beams. The causal source of this discrepancy is is believed to be two photon exchange (TPE). Recent precision experiments at $Q^2$ below 2.5 $(\mathrm{GeV}/c)^2$ found smaller than expected but clear indication of two photon exchange. However, they...Go to contribution page
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David Gaskell (Jefferson Lab)9/15/17, 9:45 AMMeasurements of Deep Inelastic Scattering (DIS) from nuclei, aimed at understanding the nuclear dependence of inelastic structure functions (the EMC effect), are typically performed at high energies, hence effects due to the acceleration of electrons in the Coulomb field of a large $Z$ nucleus are usually ignored. However, there are certain kinematics, in particular at large...Go to contribution page
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Michael Paolone (Temple University)9/15/17, 10:40 AMIn order to determine the Coulomb sum in nuclei, a precision measurement of inclusive electron scattering cross sections in the quasi-elastic region was performed at Jefferson Lab. Incident electrons with energies ranging from 0.4 GeV to 4 GeV scattered from $^{4}He$,$^{12}C$,$^{56}Fe$ and $^{208}Pb$ nuclei at four scattering angles ($15^{\circ},60^{\circ},90^{\circ},120^{\circ}$) and...Go to contribution page
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Oleksandr Koshchii (George Washington University)9/15/17, 11:15 AMElastic electron/positron scattering off a nucleus has proved to be an efficient tool to study the structure of nucleons. Modern cross section and asymmetry measurements at Jlab require radiative corrections to be taken into account. In particular, two-photon exchange (TPE) effects beyond the standard model-independent contributions have to be considered at the current level of precision....Go to contribution page
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V. Tioukine9/15/17, 1:00 PM
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Riad Suleiman (Jefferson Lab)9/15/17, 1:30 PMHighlights of R&D to improve the performance of polarized electron sources and prolong the lifetime of GaAs Superlattice will be presented.Go to contribution page
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Erdong Wang (bnl)9/15/17, 2:00 PM
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Jiquan Guo (Jefferson Lab)9/15/17, 2:50 PMJLEIC polarized positron program calls for a luminosity no more than one order of magnitude lower than the electron program. In this talk, a PEPPo based positron beam formation scheme will be presented. The combination of PEPPo’s low positron yield, the low duty factor injection bunch train required by JLEIC e-/e+ ring, as well as the mismatch of the JLEIC and CEBAF RF frequency, pose major...Go to contribution page
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Chase Boulware (Niowave, Inc.)9/15/17, 3:20 PMHigh power electron beams from superconducting radio-frequency (SRF) linacs have numerous commercial applications including x-ray sterilization, active interrogation and radiography, industrial and medical isotope production, and free electron lasers. Many of these applications use an x-ray beam generated when the electrons strike a high-Z target. Such a target can be optimized for production...Go to contribution page
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Andrei Afanasev (GWU)Interference PhysicsOral ContributionI will present an overview of the higher-order QED effects in lepton scattering on nucleons and nuclei. Availability of the positron beams provides a unique opportunity for direct measurements of C-odd asymmetries, when compared to their counterparts in electron scattering. The studies of TMD’s in semi-inclusive lepton scattering show that T-odd spin asymmetries are typically a few per...Go to contribution page
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James Alexander
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Petr Stepanov (1Center for Photochemical Sciences, Bowling Green State University, OH, USA)PosterCoincidence Doppler broadening (CDB) spectroscopy is a powerful technique to characterize defects and study electron-positron states in a wide range of materials. A new method for processing a two-dimensional Doppler spectrum into a single-dimensional one was developed. The new routine performs two-dimensional background fitting of the CDB spectra and its subtraction from raw experimental...Go to contribution page
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Mr Sahil Agarwal (BGSU)PosterAbstract Transparent ceramics are emerging as excellent candidates for many electro-optical applications such as solid-state lasers, optical window materials and scintillators. In this work, we apply positron annihilation spectroscopy for the first time to study transparent ceramics and its related interesting phenomena. Our recent work revealed a novel luminescence phenomenon in Ce doped...Go to contribution page
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Ian Cloet (Argonne National Laboratory)
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Alessandro Pilloni (Jefferson Lab)We discuss the activities of the Joint Physics Analysis Center in the field of hadron spectroscopy, in particular about the identification of the exotic XYZ statesGo to contribution page
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Erdong Wang (bnl)Positron Source and Beam PhysicsOral ContributionIn order to construct a future electron-ion collider with high luminosity, a high average current, and high bunch charge, a polarized electron source is under R&D at Brookhaven National Laboratory. We present the R&D plan for achieving the required charge and current in the polarized eRHIC gun. The background is the low-risk Linac-Ring eRHIC plan of using a number of individual guns with RF...Go to contribution page
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Volodymyr Myronenko (Deutsches-Elektronen Synchrotron)Test of the Standard ModelOral ContributionThe electron-proton collide HERA (Hamburg, Germany) has proven to be a valuable facility for studying proton structure, hard QCD processes, EW phenomena and searches for new physics. For the run period from 2000 till 2007 the HERA collider was upgraded with spin rotators in order to study various physical phenomena using precisely known longitudinal polarisation of the lepton beam. We give an...Go to contribution page
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J. David Van Horn (University of Missouri-Kansas City)PosterThe interactions of energy and particles in asymmetric substances has been of fundamental research interest since the discovery of chirality [1]. A well-studied asymmetric crystalline material is α-quartz [2], which has a helical structure associated with its crystallographic z-axis. Previously, we reported a large difference in ‘free positron’ annihilation lifetime and intensity between...Go to contribution page
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Ms Pooneh Saadatkia (Bowling Green State University)PosterComplex oxides with the ABO3 perovskite crystal structure reveal a range of spectacular phenomena such as superconductivity, ferroelectricity, and metal-insulator transitions. SrTiO3, has been the focus of intense research in the world of oxide materials due to its functional, dielectric and ferroelectric properties. Vacancies are usually suggested to be the dominant point defects in...Go to contribution page
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Rolland Johnson (Muons, Inc.)Positron Source and Beam PhysicsOral ContributionNovel electron gun features are required to enhance the peak and/or average beam brightness by reducing the emittances of electron bunches while allowing the guns to operate at a high repetition rate using laser excitation of the photocathode. The generation of surface acoustical waves (SAW) on piezoelectric substrates is known to produce strong piezoelectric fields that propagate on the...Go to contribution page
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Ali Koyman
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