L. J. Kaufman - Jefferson Lab Hall A Collaboration

L. J. Kaufman
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L. J. Kaufman
Jefferson Lab Hall A Collaboration

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Nuclear Experiment (33)
Physics - Instrumentation and Detectors (25)
High Energy Physics - Experiment (20)
High Energy Physics - Phenomenology (3)
Physics - Atomic Physics (2)
Physics - Biological Physics (1)
Physics - Soft Condensed Matter (1)
Nuclear Theory (1)
Physics - Optics (1)

Publications Authored By L. J. Kaufman

Searches for double beta decay of $^{134}\text{Xe}$ were performed with EXO-200, a single-phase liquid xenon detector designed to search for neutrinoless double beta decay of $^{136}\text{Xe}$. Using an exposure of $29.6\text{ kg}\!\cdot\!\text{yr}$, the lower limits of $\text{T}_{1/2}^{2\nu\beta\!\beta}>8. Read More

We report results from a systematic measurement campaign conducted to identify low radioactivity materials for the construction of the EXO-200 double beta decay experiment. Partial results from this campaign have already been reported in a 2008 paper by the EXO collaboration. Here we release the remaining data, collected since 2007, to the public. Read More

The EXO-200 Collaboration is searching for neutrinoless double beta decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the transport of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. Here we present measurements of the transverse diffusion constant and drift velocity of electrons at drift fields between 20~V/cm and 615~V/cm using EXO-200 data. Read More

This proceedings contribution reports the first experimental search for Lorentz- and CPT-violating signals specifically studying the effect of the Standard-Model Extension (SME) oscillation-free momentum-independent neutrino coupling operator in the double beta decay process. The search has been performed using an exposure of 100 kg yr of $^{136}$Xe with the EXO-200 detector. No significant evidence of the spectral modification due to isotropic Lorentz violation was found. Read More

The energy resolution of the EXO-200 detector is limited by electronics noise in the measurement of the scintillation response. Here we present a new technique to extract optimal scintillation energy measurements for signals split across multiple channels in the presence of correlated noise. The implementation of these techniques improves the energy resolution of the detector at the neutrinoless double beta decay Q-value from $\left[1. Read More

$^{136}$Xe is a 0{\nu}{\beta}{\beta} decay candidate isotope, and is used in multiple experiments searching for this hypothetical decay mode. These experiments require precise information about neutron capture for their background characterization and minimization. Thermal and resonant neutron capture on $^{136}$Xe have been measured at the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. Read More

A search for Lorentz- and CPT-violating signals in the double beta decay spectrum of $^{136}$Xe has been performed using an exposure of 100 kg$\cdot$yr with the EXO-200 detector. No significant evidence of the spectral modification due to isotropic Lorentz-violation was found, and a two-sided limit of $-2.65 \times 10^{-5 } \; \textrm{GeV} < \mathring{a}^{(3)}_{\text{of}} < 7. Read More

As neutrinoless double-beta decay experiments become more sensitive and intrinsic radioactivity in detector materials is reduced, previously minor contributions to the background must be understood and eliminated. With this in mind, cosmogenic backgrounds have been studied with the EXO-200 experiment. Using the EXO-200 TPC, the muon flux (through a flat horizontal surface) underground at the Waste Isolation Pilot Plant (WIPP) has been measured to be {\Phi} = 4. Read More

EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless double-beta decay of $^{136}$Xe to the ground state of $^{136}$Ba. We report here on a search for the two-neutrino double-beta decay of $^{136}$Xe to the first $0^+$ excited state, $0^+_1$, of $^{136}$Ba based on a 100 kg$\cdot$yr exposure of $^{136}$Xe. Using a specialized analysis employing a machine learning algorithm, we obtain a 90% CL half-life sensitivity of $1. Read More

The COHERENT collaboration's primary objective is to measure coherent elastic neutrino-nucleus scattering (CEvNS) using the unique, high-quality source of tens-of-MeV neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). In spite of its large cross section, the CEvNS process has never been observed, due to tiny energies of the resulting nuclear recoils which are out of reach for standard neutrino detectors. The measurement of CEvNS has now become feasible, thanks to the development of ultra-sensitive technology for rare decay and weakly-interacting massive particle (dark matter) searches. Read More

Alpha decays in the EXO-200 detector are used to measure the fraction of charged $^{218}\mathrm{Po}$ and $^{214}\mathrm{Bi}$ daughters created from alpha and beta decays, respectively. $^{222}\mathrm{Rn}$ alpha decays in liquid xenon (LXe) are found to produce $^{218}\mathrm{Po}^{+}$ ions $50.3 \pm 3. Read More

We present final results on the photon electroproduction ($\vec{e}p\rightarrow ep\gamma$) cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region from Jefferson Lab experiment E00-110. Results from an analysis of a subset of these data were published before, but the analysis has been improved which is described here at length, together with details on the experimental setup. Furthermore, additional data have been analyzed resulting in photon electroproduction cross sections at new kinematic settings, for a total of 588 experimental bins. Read More

Authors: C. Adams, J. R. Alonso, A. M. Ankowski, J. A. Asaadi, J. Ashenfelter, S. N. Axani, K. Babu, C. Backhouse, H. R. Band, P. S. Barbeau, N. Barros, A. Bernstein, M. Betancourt, M. Bishai, E. Blucher, J. Bouffard, N. Bowden, S. Brice, C. Bryan, L. Camilleri, J. Cao, J. Carlson, R. E. Carr, A. Chatterjee, M. Chen, S. Chen, M. Chiu, E. D. Church, J. I. Collar, G. Collin, J. M. Conrad, M. R. Convery, R. L. Cooper, D. Cowen, H. Davoudiasl, A. De Gouvea, D. J. Dean, G. Deichert, F. Descamps, T. DeYoung, M. V. Diwan, Z. Djurcic, M. J. Dolinski, J. Dolph, B. Donnelly, D. A. Dwyer, S. Dytman, Y. Efremenko, L. L. Everett, A. Fava, E. Figueroa-Feliciano, B. Fleming, A. Friedland, B. K. Fujikawa, T. K. Gaisser, M. Galeazzi, D. C. Galehouse, A. Galindo-Uribarri, G. T. Garvey, S. Gautam, K. E. Gilje, M. Gonzalez-Garcia, M. C. Goodman, H. Gordon, E. Gramellini, M. P. Green, A. Guglielmi, R. W. Hackenburg, A. Hackenburg, F. Halzen, K. Han, S. Hans, D. Harris, K. M. Heeger, M. Herman, R. Hill, A. Holin, P. Huber, D. E. Jaffe, R. A. Johnson, J. Joshi, G. Karagiorgi, L. J. Kaufman, B. Kayser, S. H. Kettell, B. J. Kirby, J. R. Klein, Yu. G. Kolomensky, R. M. Kriske, C. E. Lane, T. J. Langford, A. Lankford, K. Lau, J. G. Learned, J. Ling, J. M. Link, D. Lissauer, L. Littenberg, B. R. Littlejohn, S. Lockwitz, M. Lokajicek, W. C. Louis, K. Luk, J. Lykken, W. J. Marciano, J. Maricic, D. M. Markoff, D. A. Martinez Caicedo, C. Mauger, K. Mavrokoridis, E. McCluskey, D. McKeen, R. McKeown, G. Mills, I. Mocioiu, B. Monreal, M. R. Mooney, J. G. Morfin, P. Mumm, J. Napolitano, R. Neilson, J. K. Nelson, M. Nessi, D. Norcini, F. Nova, D. R. Nygren, G. D. Orebi Gann, O. Palamara, Z. Parsa, R. Patterson, P. Paul, A. Pocar, X. Qian, J. L. Raaf, R. Rameika, G. Ranucci, H. Ray, D. Reyna, G. C. Rich, P. Rodrigues, E. Romero Romero, R. Rosero, S. D. Rountree, B. Rybolt, M. C. Sanchez, G. Santucci, D. Schmitz, K. Scholberg, D. Seckel, M. Shaevitz, R. Shrock, M. B. Smy, M. Soderberg, A. Sonzogni, A. B. Sousa, J. Spitz, J. M. St. John, J. Stewart, J. B. Strait, G. Sullivan, R. Svoboda, A. M. Szelc, R. Tayloe, M. A. Thomson, M. Toups, A. Vacheret, M. Vagins, R. G. Van de Water, R. B. Vogelaar, M. Weber, W. Weng, M. Wetstein, C. White, B. R. White, L. Whitehead, D. W. Whittington, M. J. Wilking, R. J. Wilson, P. Wilson, D. Winklehner, D. R. Winn, E. Worcester, L. Yang, M. Yeh, Z. W. Yokley, J. Yoo, B. Yu, J. Yu, C. Zhang

The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. Read More

The search for neutrinoless double-beta decay (0{\nu}{\beta}{\beta}) requires extremely low background and a good understanding of their sources and their influence on the rate in the region of parameter space relevant to the 0{\nu}{\beta}{\beta} signal. We report on studies of various {\beta}- and {\gamma}-backgrounds in the liquid- xenon-based EXO-200 0{\nu}{\beta}{\beta} experiment. With this work we try to better understand the location and strength of specific background sources and compare the conclusions to radioassay results taken before and during detector construction. Read More

An RF ion-funnel technique has been developed to extract ions from a high-pressure (10 bar) noble-gas environment into vacuum ($10^{-6}$ mbar). Detailed simulations have been performed and a prototype has been developed for the purpose of extracting $^{136}$Ba ions from Xe gas with high efficiency. With this prototype, ions have been extracted for the first time from high-pressure xenon gas and argon gas. Read More

Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence and bleaching of the fluorescence reveal the existence of different matrix sites. Read More

EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless double-beta decay of $^{136}$Xe. Here we report on a search for various Majoron-emitting modes based on 100 kg$\cdot$yr exposure of $^{136}$Xe. A lower limit of $T^{^{136}Xe}_{1/2} >1. Read More

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope $^{136}$Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). Read More

Affiliations: 1Jefferson Lab Hall A Collaboration, 2Jefferson Lab Hall A Collaboration, 3Jefferson Lab Hall A Collaboration, 4Jefferson Lab Hall A Collaboration, 5Jefferson Lab Hall A Collaboration, 6Jefferson Lab Hall A Collaboration, 7Jefferson Lab Hall A Collaboration, 8Jefferson Lab Hall A Collaboration, 9Jefferson Lab Hall A Collaboration, 10Jefferson Lab Hall A Collaboration, 11Jefferson Lab Hall A Collaboration, 12Jefferson Lab Hall A Collaboration, 13Jefferson Lab Hall A Collaboration, 14Jefferson Lab Hall A Collaboration, 15Jefferson Lab Hall A Collaboration, 16Jefferson Lab Hall A Collaboration, 17Jefferson Lab Hall A Collaboration, 18Jefferson Lab Hall A Collaboration, 19Jefferson Lab Hall A Collaboration, 20Jefferson Lab Hall A Collaboration, 21Jefferson Lab Hall A Collaboration, 22Jefferson Lab Hall A Collaboration, 23Jefferson Lab Hall A Collaboration, 24Jefferson Lab Hall A Collaboration, 25Jefferson Lab Hall A Collaboration, 26Jefferson Lab Hall A Collaboration, 27Jefferson Lab Hall A Collaboration, 28Jefferson Lab Hall A Collaboration, 29Jefferson Lab Hall A Collaboration, 30Jefferson Lab Hall A Collaboration, 31Jefferson Lab Hall A Collaboration, 32Jefferson Lab Hall A Collaboration, 33Jefferson Lab Hall A Collaboration, 34Jefferson Lab Hall A Collaboration, 35Jefferson Lab Hall A Collaboration, 36Jefferson Lab Hall A Collaboration, 37Jefferson Lab Hall A Collaboration, 38Jefferson Lab Hall A Collaboration, 39Jefferson Lab Hall A Collaboration, 40Jefferson Lab Hall A Collaboration, 41Jefferson Lab Hall A Collaboration, 42Jefferson Lab Hall A Collaboration, 43Jefferson Lab Hall A Collaboration, 44Jefferson Lab Hall A Collaboration, 45Jefferson Lab Hall A Collaboration, 46Jefferson Lab Hall A Collaboration, 47Jefferson Lab Hall A Collaboration, 48Jefferson Lab Hall A Collaboration, 49Jefferson Lab Hall A Collaboration, 50Jefferson Lab Hall A Collaboration, 51Jefferson Lab Hall A Collaboration, 52Jefferson Lab Hall A Collaboration, 53Jefferson Lab Hall A Collaboration, 54Jefferson Lab Hall A Collaboration, 55Jefferson Lab Hall A Collaboration, 56Jefferson Lab Hall A Collaboration, 57Jefferson Lab Hall A Collaboration, 58Jefferson Lab Hall A Collaboration, 59Jefferson Lab Hall A Collaboration, 60Jefferson Lab Hall A Collaboration, 61Jefferson Lab Hall A Collaboration, 62Jefferson Lab Hall A Collaboration, 63Jefferson Lab Hall A Collaboration, 64Jefferson Lab Hall A Collaboration, 65Jefferson Lab Hall A Collaboration, 66Jefferson Lab Hall A Collaboration, 67Jefferson Lab Hall A Collaboration, 68Jefferson Lab Hall A Collaboration, 69Jefferson Lab Hall A Collaboration, 70Jefferson Lab Hall A Collaboration, 71Jefferson Lab Hall A Collaboration, 72Jefferson Lab Hall A Collaboration, 73Jefferson Lab Hall A Collaboration, 74Jefferson Lab Hall A Collaboration, 75Jefferson Lab Hall A Collaboration, 76Jefferson Lab Hall A Collaboration, 77Jefferson Lab Hall A Collaboration, 78Jefferson Lab Hall A Collaboration, 79Jefferson Lab Hall A Collaboration, 80Jefferson Lab Hall A Collaboration, 81Jefferson Lab Hall A Collaboration, 82Jefferson Lab Hall A Collaboration, 83Jefferson Lab Hall A Collaboration, 84Jefferson Lab Hall A Collaboration, 85Jefferson Lab Hall A Collaboration, 86Jefferson Lab Hall A Collaboration, 87Jefferson Lab Hall A Collaboration, 88Jefferson Lab Hall A Collaboration, 89Jefferson Lab Hall A Collaboration, 90Jefferson Lab Hall A Collaboration, 91Jefferson Lab Hall A Collaboration, 92Jefferson Lab Hall A Collaboration, 93Jefferson Lab Hall A Collaboration, 94Jefferson Lab Hall A Collaboration, 95Jefferson Lab Hall A Collaboration, 96Jefferson Lab Hall A Collaboration, 97Jefferson Lab Hall A Collaboration, 98Jefferson Lab Hall A Collaboration

In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei can provide information on the details of the effective hyperon-nucleon interaction. Electroproduction of the hypernucleus Lambda-9Li has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a 9Be target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. Read More

Many extensions of the Standard Model of particle physics suggest that neutrinos should be Majorana-type fermions, but this assumption is difficult to confirm. Observation of neutrinoless double-beta decay ($0\nu \beta \beta$), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with $^{76}$Ge (GERDA experiment) and $^{136}$Xe (KamLAND-Zen and EXO-200 experiments) have established the lifetime of this decay to be longer than $10^{25}$ yr, corresponding to a limit on the neutrino mass of 0. Read More

Authors: A. de Gouvea, K. Pitts, K. Scholberg, G. P. Zeller, J. Alonso, A. Bernstein, M. Bishai, S. Elliott, K. Heeger, K. Hoffman, P. Huber, L. J. Kaufman, B. Kayser, J. Link, C. Lunardini, B. Monreal, J. G. Morfin, H. Robertson, R. Tayloe, N. Tolich, K. Abazajian, T. Akiri, C. Albright, J. Asaadi, K. S Babu, A. B. Balantekin, P. Barbeau, M. Bass, A. Blake, A. Blondel, E. Blucher, N. Bowden, S. J. Brice, A. Bross, B. Carls, F. Cavanna, B. Choudhary, P. Coloma, A. Connolly, J. Conrad, M. Convery, R. L. Cooper, D. Cowen, H. da Motta, T. de Young, F. Di Lodovico, M. Diwan, Z. Djurcic, M. Dracos, S. Dodelson, Y. Efremenko, T. Ekelof, J. L. Feng, B. Fleming, J. Formaggio, A. Friedland, G. Fuller, H. Gallagher, S. Geer, M. Gilchriese, M. Goodman, D. Grant, G. Gratta, C. Hall, F. Halzen, D. Harris, M. Heffner, R. Henning, J. L. Hewett, R. Hill, A. Himmel, G. Horton-Smith, A. Karle, T. Katori, E. Kearns, S. Kettell, J. Klein, Y. Kim, Y. K. Kim, Yu. Kolomensky, M. Kordosky, Yu. Kudenko, V. A. Kudryavtsev, K. Lande, K. Lang, R. Lanza, K. Lau, H. Lee, Z. Li, B. R. Littlejohn, C. J. Lin, D. Liu, H. Liu, K. Long, W. Louis, K. B. Luk, W. Marciano, C. Mariani, M. Marshak, C. Mauger, K. T. McDonald, K. McFarland, R. McKeown, M. Messier, S. R. Mishra, U. Mosel, P. Mumm, T. Nakaya, J. K. Nelson, D. Nygren, G. D. Orebi Gann, J. Osta, O. Palamara, J. Paley, V. Papadimitriou, S. Parke, Z. Parsa, R. Patterson, A. Piepke, R. Plunkett, A. Poon, X. Qian, J. Raaf, R. Rameika, M. Ramsey-Musolf, B. Rebel, R. Roser, J. Rosner, C. Rott, G. Rybka, H. Sahoo, S. Sangiorgio, D. Schmitz, R. Shrock, M. Shaevitz, N. Smith, M. Smy, H. Sobel, P. Sorensen, A. Sousa, J. Spitz, T. Strauss, R. Svoboda, H. A. Tanaka, J. Thomas, X. Tian, R. Tschirhart, C. Tully, K. Van Bibber, R. G. Van de Water, P. Vahle, P. Vogel, C. W. Walter, D. Wark, M. Wascko, D. Webber, H. Weerts, C. White, H. White, L. Whitehead, R. J. Wilson, L. Winslow, T Wongjirad, E. Worcester, M. Yokoyama, J. Yoo, E. D. Zimmerman

This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos. Read More

We report on an improved measurement of the 2\nu \beta \beta\ half-life of Xe-136 performed by EXO-200. The use of a large and homogeneous time projection chamber allows for the precise estimate of the fiducial mass used for the measurement, resulting in a small systematic uncertainty. We also discuss in detail the data analysis methods used for double-beta decay searches with EXO-200, while emphasizing those directly related to the present measurement. Read More

The search for neutrinoless double beta decay is a rich source for new physics. The observation of this decay will lead to understanding of the absolute mass scale of neutrinos, the Majorana nature of the neutrino (whether the neutrino is its own anti-particle), and lepton number violation. Double beta decay is being investigated around the world by several experiments using different candidate isotopes. Read More

The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. Read More

Authors: The HAPPEX, PREX Collaborations, :, S. Abrahamyan, A. Acha, A. Afanasev, Z. Ahmed, H. Albataineh, K. Aniol, D. S. Armstrong, W. Armstrong, J. Arrington, T. Averett, B. Babineau, S. L. Bailey, J. Barber, A. Barbieri, A. Beck, V. Bellini, R. Beminiwattha, H. Benaoum, J. Benesch, F. Benmokhtar, P. Bertin, T. Bielarski, W. Boeglin, P. Bosted, F. Butaru, E. Burtin, J. Cahoon, A. Camsonne, M. Canan, P. Carter, C. C. Chang, G. D. Cates, Y. C. Chao, C. Chen, J. P. Chen, Seonho Choi, E. Chudakov, E. Cisbani, B. Craver, F. Cusanno, M. M. Dalton, R. De Leo, K. de Jager, W. Deconinck, P. Decowski, D. Deepa, X. Deng, A. Deur, D. Dutta, A. Etile, C. Ferdi, R. J. Feuerbach, J. M. Finn, D. Flay, G. B. Franklin, M. Friend, S. Frullani, E. Fuchey, S. A. Fuchs, K. Fuoti, F. Garibaldi, E. Gasser, R. Gilman, A. Giusa, A. Glamazdin, L. E. Glesener, J. Gomez, M. Gorchtein, J. Grames, K. Grimm, C. Gu, O. Hansen, J. Hansknecht, O. Hen, D. W. Higinbotham, R. S. Holmes, T. Holmstrom, C. J. Horowitz, J. Hoskins, J. Huang, T. B. Humensky, C. E. Hyde, H. Ibrahim, F. Itard, C. M. Jen, E. Jensen, X. Jiang, G. Jin, S. Johnston, J. Katich, L. J. Kaufman, A. Kelleher, K. Kliakhandler, P. M. King, A. Kolarkar, S. Kowalski, E. Kuchina, K. S. Kumar, L. Lagamba, D. Lambert, P. LaViolette, J. Leacock, J. Leckey IV, J. H. Lee, J. J. LeRose, D. Lhuillier, R. Lindgren, N. Liyanage, N. Lubinsky, J. Mammei, F. Mammoliti, D. J. Margaziotis, P. Markowitz, M. Mazouz, K. McCormick, A. McCreary, D. McNulty, D. G. Meekins, L. Mercado, Z. E. Meziani, R. W. Michaels, M. Mihovilovic, B. Moffit, P. Monaghan, N. Muangma, C. Munoz-Camacho, S. Nanda, V. Nelyubin, D. Neyret, Nuruzzaman, Y. Oh, K. Otis, A. Palmer, D. Parno, K. D. Paschke, S. K. Phillips, M. Poelker, R. Pomatsalyuk, M. Posik, M. Potokar, K. Prok, A. J. R. Puckett, X. Qian, Y. Qiang, B. Quinn, A. Rakhman, P. E. Reimer, B. Reitz, S. Riordan, J. Roche, P. Rogan, G. Ron, G. Russo, K. Saenboonruang, A. Saha, B. Sawatzky, A. Shahinyan, R. Silwal, J. Singh, S. Sirca, K. Slifer, R. Snyder, P. Solvignon, P. A. Souder, M. L. Sperduto, R. Subedi, M. L. Stutzman, R. Suleiman, V. Sulkosky, C. M. Sutera, W. A. Tobias, W. Troth, G. M. Urciuoli, P. Ulmer, A. Vacheret, E. Voutier, B. Waidyawansa, D. Wang, K. Wang, J. Wexler, A. Whitbeck, R. Wilson, B. Wojtsekhowski, X. Yan, H. Yao, Y. Ye, Z. Ye, V. Yim, L. Zana, X. Zhan, J. Zhang, Y. Zhang, X. Zheng, V. Ziskin, P. Zhu

We have measured the beam-normal single-spin asymmetry $A_n$ in the elastic scattering of 1-3 GeV transversely polarized electrons from $^1$H and for the first time from $^4$He, $^{12}$C, and $^{208}$Pb. For $^1$H, $^4$He and $^{12}$C, the measurements are in agreement with calculations that relate $A_n$ to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the $^{208}$Pb result is significantly smaller than the corresponding prediction using the same formalism. Read More

EXO-200 is an experiment designed to search for double beta decay of $^{136}$Xe with a single-phase, liquid xenon detector. It uses an active mass of 110 kg of xenon enriched to 80.6% in the isotope 136 in an ultra-low background time projection chamber capable of simultaneous detection of ionization and scintillation. Read More

We describe purity measurements of the natural and enriched xenon stockpiles used by the EXO-200 double beta decay experiment based on a mass spectrometry technique. The sensitivity of the spectrometer is enhanced by several orders of magnitude by the presence of a liquid nitrogen cold trap, and many impurity species of interest can be detected at the level of one part-per-billion or better. We have used the technique to screen the EXO-200 xenon before, during, and after its use in our detector, and these measurements have proven useful. Read More

We report the observation of two-neutrino double-beta decay in Xe-136 with T_1/2 = 2.11 +- 0.04 (stat. Read More

We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Read More

A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon TPC of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute (SLPM) of xenon gas with 750 torr differential pressure. Read More

We describe a source capable of producing single barium ions through nuclear recoils in radioactive decay. The source is fabricated by electroplating 148Gd onto a silicon {\alpha}-particle detector and vapor depositing a layer of BaF2 over it. 144Sm recoils from the alpha decay of 148Gd are used to dislodge Ba+ ions from the BaF2 layer and emit them in the surrounding environment. Read More

Authors: S. Riordan, S. Abrahamyan, B. Craver, A. Kelleher, A. Kolarkar, J. Miller, G. D. Cates, N. Liyanage, B. Wojtsekhowski, A. Acha, K. Allada, B. Anderson, K. A. Aniol, J. R. M. Annand, J. Arrington, T. Averett, A. Beck, M. Bellis, W. Boeglin, H. Breuer, J. R. Calarco, A. Camsonne, J. P. Chen, E. Chudakov, L. Coman, B. Crowe, F. Cusanno, D. Day, P. Degtyarenko, P. A. M. Dolph, C. Dutta, C. Ferdi, C. Fernandez-Ramirez, R. Feuerbach, L. M. Fraile, G. Franklin, S. Frullani, S. Fuchs, F. Garibaldi, N. Gevorgyan, R. Gilman, A. Glamazdin, J. Gomez, K. Grimm, J. O. Hansen, J. L. Herraiz, D. W. Higinbotham, R. Holmes, T. Holmstrom, D. Howell, C. W. deJager, X. Jiang, M. K. Jones, J. Katich, L. J. Kaufman, M. Khandaker, J. J. Kelly, D. Kiselev, W. Korsch, J. LeRose, R. Lindgren, P. Markowitz, D. J. Margaziotis, S. May-Tal Beck, S. Mayilyan, K. McCormick, Z. E. Meziani, R. Michaels, B. Moffit, S. Nanda, V. Nelyubin, T. Ngo, D. M. Nikolenko, B. Norum, L. Pentchev, C. F. Perdrisat, E. Piasetzky, R. Pomatsalyuk, D. Protopopescu, A. J. R. Puckett, V. A. Punjabi, X. Qian, Y. Qiang, B. Quinn, I. Rachek, R. D. Ransome, P. E. Reimer, B. Reitz, J. Roche, G. Ron, O. Rondon, G. Rosner, A. Saha, M. Sargsian, B. Sawatzky, J. Segal, M. Shabestari, A. Shahinyan, Yu. Shestakov, J. Singh, S. Sirca, P. Souder, S. Stepanyan, V. Stibunov, V. Sulkosky, S. Tajima, W. A. Tobias, J. M. Udias, G. M. Urciuoli, B. Vlahovic, H. Voskanyan, K. Wang, F. R. Wesselmann, J. R. Vignote, S. A. Wood, J. Wright, H. Yao, X. Zhu

The electric form factor of the neutron was determined from studies of the reaction He3(e,e'n)pp in quasi-elastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. Read More

Oxygen, nitrogen and methane purification efficiencies for a common zirconium getter are measured in 1050 Torr of xenon gas. Starting with impurity concentrations near 10^{-6} g/g, the outlet impurity level is found to be less than 120*10^{-12} g/g for O2 and less than 950*10^{-12} g/g for N2. For methane we find residual contamination of the purified gas at concentrations varying over three orders of magnitude, depending on the purifier temperature and the gas flow rate. Read More

We report on the development and performance of a high-sensitivity purity-analysis technique for gaseous xenon. The gas is sampled at macroscopic pressure from the system of interest using a UHV leak valve. The xenon present in the sample is removed with a liquid-nitrogen cold trap, and the remaining impurities are observed with a standard vacuum mass-spectroscopy device. Read More

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where a proton is knocked-out of the nucleus with high momentum transfer and high missing momentum, show that in 12C the neutron-proton pairs are nearly twenty times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars. Read More

We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. Read More

EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector. Read More

An experimental study of the 16O(e,e'K^+)16N_Lambda reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K^+)Lambda,Sigma_0 exclusive reactions and a precise calibration of the energy scale. Read More

We report the observation of imaging beyond the diffraction limit due to bound surface states in negative refraction photonic crystals. We achieve an effective negative index figure-of-merit [-Re(n)/Im(n)] of at least 380, ~125x improvement over recent efforts in the near-infrared, with a 0.4 THz bandwidth. Read More

An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferson Lab on a $^{12}$C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Read More

Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich and colloid-poor regions. Gelation results when interconnected colloid-rich regions solidify. We show that this occurs when these regions undergo a glass transition, leading to dynamic arrest of the spinodal decomposition. Read More

Sexual reproduction presents significant challenges to formal treatment of evolutionary processes. A starting point for systematic treatments of ecological and evolutionary phenomena has been provided by the gene centered view of evolution which assigns effective fitness to each allele instead of each organism. The gene centered view can be formalized as a dynamic mean field approximation applied to genes in reproduction / selection dynamics. Read More