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Your search keyword '"Chang, C.‐C."' showing total 29 results
Start Over Author "Chang, C.‐C." Topic fos: physical sciences
29 results on '"Chang, C.‐C."'

1. Measurement of the 3He Spin-Structure Functions and of Neutron (3He) Spin-Dependent Sum Rules at 0.035

Author

Sulkosky, V., Singh, J. T., Peng, C., Chen, J. -P., Deur, A., Abrahamyan, S., Aniol, K. A., Armstrong, D. S., Averett, T., Bailey, S. L., Beck, A., Bertin, P., Butaru, F., Boeglin, W., Camsonne, A., Cates, G. D., Chang, C. C., Choi, Seonho, Chudakov, E., Coman, L., Cornejo, J. C, Craver, B., Cusanno, F., De Leo, R., de Jager, C. W., Denton, J. D., Dhamija, S., Feuerbach, R., Finn, J. M., Frullani, S., Fuoti, K., Gao, H., Garibaldi, F., Gayou, O., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Hansen, J. -O., Hayes, D., Hersman, B., Higinbotham, D. W., Holmstrom, T., Humensky, T. B., Hyde, C. E., Ibrahim, H., Iodice, M., Jiang, X., Kaufman, L. J., Kelleher, A., Keister, K. E., Kim, W., Kolarkar, A., Kolb, N., Korsch, W., Kramer, K., Kumbartzki, G., Lagamba, L., Laine, V., Laveissiere, G., Lerose, J. J., Lhuillier, D., Lindgren, R., Liyanage, N., Lu, H. -J., Ma, B., Margaziotis, D. J., Markowitz, P., McCormick, K., Meziane, M., Meziani, Z. -E., Michaels, R., Moffit, B., Monaghan, P., Nanda, S., Niedziela, J., Niskin, M., Pandolfi, R., Paschke, K. D., Potokar, M., Puckett, A., Punjabi, V. A., Qiang, Y., Ransome, R., Reitz, B., Roche, R., Saha, A., Shabetai, A., Sirca, S., Slifer, K., Snyder, R., Solvignon, P., Stringer, R., Subedi, R., Tobias, W. A., Ton, N., Ulmer, P. E., Urciuoli, G. M., Vacheret, A., Voutier, E., Wang, K., Wan, L., Wojtsekhowski, B., Woo, S., Yao, H., Yuan, J., Zhan, X., Zheng, X., and Zhu, L.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

The spin-structure functions $g_1$ and $g_2$, and the spin-dependent partial cross-section $��_\mathrm{TT}$ have been extracted from the polarized cross-sections differences, $����_{\parallel}\hspace{-0.06cm}\left(��,Q^{2}\right)$ and $����_{\perp}\hspace{-0.06cm}\left(��,Q^{2}\right)$ measured for the $\vec{^\textrm{3}\textrm{He}}(\vec{\textrm{e}},\textrm{e}')\textrm{X}$ reaction, in the E97-110 experiment at Jefferson Lab. Polarized electrons with energies from 1.147 to 4.404 GeV were scattered at angles of 6$^{\circ}$ and 9$^{\circ}$ from a longitudinally or transversely polarized $^{3}$He target. The data cover the kinematic regions of the quasi-elastic, resonance production and beyond. From the extracted spin-structure functions, the first moments $\overline{��_1}\hspace{-0.06cm}\left(Q^{2}\right)$, $��_2\hspace{-0.06cm}\left(Q^{2}\right)$ and $I_{\mathrm{TT}}\hspace{-0.06cm}\left(Q^{2}\right)$ are evaluated with high precision for the neutron in the $Q^2$ range from 0.035 to 0.24~GeV$^{2}$. The comparison of the data and the chiral effective field theory predictions reveals the importance of proper treatment of the $��$ degree of freedom for spin observables., 7 pages, 5 figures, 3 tables. Version published in Phys. Lett. B

Published
2019
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2. High-resolution hypernuclear spectroscopy at Jefferson Lab, Hall A

Author

Jefferson Lab Hall A Collaboration, Garibaldi, F., Acha, A., Ambrozewicz, P., Aniol, K. A., Beturin, P., Benaoum, H., Benesch, J., Bertin, P. Y., Blomqvist, K. I., Boeglin, W. U., Breuer, H., Brindza, P., Bydzovsky, P., Camsonne, A., Chang, C. C., Chen, J. -P., Choi, Seonho, Chudakov, E. A., Cisbani, E., Colilli, S., Coman, L., Cusanno, F., Craver, B. J., De Cataldo, G., de Jager, C. W., De Leo, R., Deur, A. P., Ferdi, C., Feuerbach, R. J., Folts, E., Frullani, S., Gayou, O., Giuliani, F., Gomez, J., Gricia, M., Hansen, J. O., Hayes, D., Higinbotham, D. W., Holmstrom, T. K., Hyde, C. E., Ibrahim, H. F., Iodice, M., Jiang, X., Kaufman, L. J., Kino, K., Kross, B., Lagamba, L., LeRose, J. J., Lindgren, R. A., Lucentini, M., Margaziotis, D. J., Markowitz, P., Marrone, S., Meekins, D. G., Meziani, Z. E., McCormick, K., Michaels, R. W., Millener, D. J., Miyoshi, T., Moffit, B., Monaghan, P. A., Moteabbed, M., Camacho, C. Munoz, Nanda, S., Nappi, E., Nelyubin, V. V., Norum, B. E., Okasyasu, Y., Paschke, K. D., Perdrisat, C. F., Piasetzky, E., Punjabi, V. A., Qiang, Y., Raue, B., Reimer, P. E., Reinhold, J., Reitz, B., Roche, R. E., Rodriguez, V. M., Saha, A., Santavenere, F., Sarty, A. J., Segal, J., Shahinyan, A., Singh, J., Sirca, S., Snyder, R., Solvignon, P. H., Sotona, M., Subedi, R., Sulkosky, V. A., Suzuki, T., Ueno, H., Ulmer, P. E., Urciuoli, G. M., Voutier, E., Wojtsekhowski, B. B., Zheng, X., Zorn, C., Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Jefferson Lab Hall A, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, 01 natural sciences, Nuclear Theory (nucl-th), 0103 physical sciences, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment
Abstract

The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in electroproduction on 9Be, 12C and 16O targets. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of Lambda 12B. A high-quality Lambda 16N hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for Lambda 16N, calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Lambda 9Li hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique., Comment: 27 pages, 18 figures, submitted to Physical Review C

Published
2019

3. Exclusive $��^+$ electroproduction off the proton from low to high -t

Author

Basnet, S., Huber, G. M., Li, W. B., Blok, H. P., Gaskell, D., Horn, T., Aniol, K., Arrington, J., Beise, E. J., Boeglin, W., Brash, E. J., Breuer, H., Chang, C. C., Christy, M. E., Ent, R., Gibson, E., Holt, R. J., Jin, S., Jones, M. K., Keppel, C. E., Kim, W., King, P. M., Kovaltchouk, V., Liu, J., Lolos, G. J., Mack, D. J., Margaziotis, D. J., Markowitz, P., Matsumura, A., Meekins, D., Miyoshi, T., Mkrtchyan, H., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Potterveld, D., Punjabi, V., Reimer, P., Reinhold, J., Roche, J., Sarty, A., Smith, G. R., Tadevosyan, V., Tang, L. G., Tvaskis, V., Volmer, J., Vulcan, W., Warren, G., Wood, S. A., Xu, C., and Zheng, X.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Background: Measurements of exclusive meson production are a useful tool in the study of hadronic structure. In particular, one can discern the relevant degrees of freedom at different distance scales through these studies. Purpose: To study the transition between non-perturbative and perturbative Quantum Chromodyanmics as the square of four momentum transfer to the struck proton, -t, is increased. Method: Cross sections for the $^1$H(e,e'$��^+$)n reaction were measured over the -t range of 0.272 to 2.127 GeV$^2$ with limited azimuthal coverage at fixed beam energy of 4.709 GeV, Q$^2$ of 2.4 GeV$^2$ and W of 2.0 GeV at the Thomas Jefferson National Accelerator Facility (JLab) Hall C. Results: The -t dependence of the measured $��^+$ electroproduction cross section generally agrees with prior data from JLab Halls B and C. The data are consistent with a Regge amplitude based theoretical model, but show poor agreement with a Generalized Parton Distribution (GPD) based model. Conclusion: The agreement of cross sections with prior data implies small contribution from the interference terms, and the confirmation of the change in t-slopes between the low and high -t regions previously observed in photoproduction indicates the changing nature of the electroproduction reaction in our kinematic regime., 9 pages, 5 figures Physical Review C, in press

Published
2019
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4. Short-distance matrix elements for $D^0$-meson mixing for $N_f=2+1$ lattice QCD

Author

Bazavov, A., Bernard, C., Bouchard, C. M., Chang, C. C., DeTar, C., Du, D., El-Khadra, A. X., Freeland, E. D., Gámiz, E., Gottlieb, Steven, Heller, U. M., Kronfeld, A. S., Laiho, J., Mackenzie, P. B., Neil, E. T., Simone, J. N., Sugar, R., Toussaint, D., Van de Water, R. S., and Zhou, R.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Lattice, High Energy Physics - Phenomenology (hep-ph), High Energy Physics::Lattice, High Energy Physics::Phenomenology, High Energy Physics - Lattice (hep-lat), FOS: Physical sciences, High Energy Physics::Experiment, High Energy Physics - Experiment
Abstract

We calculate in three-flavor lattice QCD the short-distance hadronic matrix elements of all five $\Delta C=2$ four-fermion operators that contribute to neutral $D$-meson mixing both in and beyond the Standard Model. We use the MILC Collaboration's $N_f = 2+1$ lattice gauge-field configurations generated with asqtad-improved staggered sea quarks. We also employ the asqtad action for the valence light quarks and use the clover action with the Fermilab interpretation for the charm quark. We analyze a large set of ensembles with pions as light as $M_\pi \approx 180$ MeV and lattice spacings as fine as $a\approx 0.045$ fm, thereby enabling good control over the extrapolation to the physical pion mass and continuum limit. We obtain for the matrix elements in the $\overline{\text{MS}}$-NDR scheme using the choice of evanescent operators proposed by Beneke \emph{et al.}, evaluated at 3 GeV, $\langle D^0|\mathcal{O}_i|\bar{D}^0 \rangle = \{0.0805(55)(16), -0.1561(70)(31), 0.0464(31)(9), 0.2747(129)(55), 0.1035(71)(21)\}~\text{GeV}^4$ ($i=1$--5). The errors shown are from statistics and lattice systematics, and the omission of charmed sea quarks, respectively. To illustrate the utility of our matrix-element results, we place bounds on the scale of CP-violating new physics in $D^0$~mixing, finding lower limits of about 10--50$\times 10^3$ TeV for couplings of $\mathrm{O}(1)$. To enable our results to be employed in more sophisticated or model-specific phenomenological studies, we provide the correlations among our matrix-element results. For convenience, we also present numerical results in the other commonly-used scheme of Buras, Misiak, and Urban., Comment: Published version, 42 pages, 18 figures

Published
2017
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5. $B^0_{(s)}$-mixing matrix elements from lattice QCD for the Standard Model and beyond

Author

Bazavov, A., Bernard, C., Bouchard, C. M., Chang, C. C., DeTar, C., Du, Daping, El-Khadra, A. X., Freeland, E. D., Gamiz, E., Gottlieb, Steven, Heller, U. M., Kronfeld, A. S., Laiho, J., Mackenzie, P. B., Neil, E. T., Simone, J., Sugar, R., Toussaint, D., Van de Water, R. S., and Zhou, Ran

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Lattice, High Energy Physics - Phenomenology (hep-ph), High Energy Physics::Lattice, High Energy Physics::Phenomenology, High Energy Physics - Lattice (hep-lat), FOS: Physical sciences, High Energy Physics::Experiment
Abstract

We calculate---for the first time in three-flavor lattice QCD---the hadronic matrix elements of all five local operators that contribute to neutral $B^0$- and $B_s$-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the expression for the neutral $B$-meson width difference. We obtain the most precise determination to date of the SU(3)-breaking ratio $\xi = 1.206(18)(6)$, where the second error stems from the omission of charm sea quarks, while the first encompasses all other uncertainties. The threefold reduction in total uncertainty, relative to the 2013 Flavor Lattice Averaging Group results, tightens the constraint from $B$ mixing on the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle. Our calculation employs gauge-field ensembles generated by the MILC Collaboration with four lattice spacings and pion masses close to the physical value. We use the asqtad-improved staggered action for the light valence quarks, and the Fermilab method for the bottom quark. We use heavy-light meson chiral perturbation theory modified to include lattice-spacing effects to extrapolate the five matrix elements to the physical point. We combine our results with experimental measurements of the neutral $B$-meson oscillation frequencies to determine the CKM matrix elements $|V_{td}| = 8.00(34)(8) \times 10^{-3}$, $|V_{ts}| = 39.0(1.2)(0.4) \times 10^{-3}$, and $|V_{td}/V_{ts}| = 0.2052(31)(10)$, which differ from CKM-unitarity expectations by about 2$\sigma$. These results and others from flavor-changing-neutral currents point towards an emerging tension between weak processes that are mediated at the loop and tree levels., Comment: 75 pp, 17 figs. Ver 2 fixes typos; corrects mistakes resulting in slight changes to results, correlation matrices; updates decay constants to agree with recent PDG update; corrects uncertainties for tree-level CKM matrix elements used in comparison, slightly reducing tensions; includes additional analyses that support mostly-nonperturbative matching; expands discussion of isospin-breaking effects

Published
2016
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6. Hadronic matrix elements of neutral-meson mixing through lattice QCD

Author

Chang, C. C.

Subjects
High Energy Physics - Lattice, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, High Energy Physics - Lattice (hep-lat), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract

Neutral-meson mixing is loop suppressed in the Standard Model, leading to the possibility of enhanced sensitivity to new physics. The uncertainty in Standard Model predictions for $B$-meson oscillation frequencies is dominated by theoretical uncertainties within the short-distance $B$-meson hadronic matrix elements, motivating the need for improved precision. In $D$-meson mixing, the Standard Model short-distance contributions are further suppressed by the GIM mechanism allowing for the possibility of large new physics enhancements. A first-principle determination of the $D$-meson short-distance hadronic matrix elements will allow for model-discrimination between the new physics theories. I review recently published and ongoing lattice calculations of hadronic matrix elements in $B$ and $D$-meson mixing with emphasis on the Fermilab lattice and MILC collaboration effort on the determination of the $B$ and $D$-meson mixing hadronic matrix elements using the methods of lattice QCD., Comment: Talk presented at CIPANP2015. 8 pages, 5 figures, LaTeX

Published
2015
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7. Spectroscopy of Lambda-9Li by electroproduction

Author

Urciuoli, G. M., Cusanno, F., Marrone, S., Acha, A., Ambrozewicz, P., Aniol, K. A., Baturin, P., Bertin, P. Y., Benaoum, H., Blomqvist, K. I., Boeglin, W. U., Breuer, H., Brindza, P., Bydzovsky, P., Camsonne, A., Chang, C. C., Chen, J. -P., Choi, Seonho, Chudakov, E. A., Cisbani, E., Colilli, S., Coman, L., Craver, B. J., De Cataldo, G., de Jager, C. W., De Leo, R., Deur, A. P., Ferdi, C., Feuerbach, R. J., Folts, E., Fratoni, R., Frullani, S., Garibaldi, F., Gayou, O., Giuliani, F., Gomez, J., Gricia, M., Hansen, J. O., Hayes, D., Higinbotham, D. W., Holmstrom, T. K., Hyde, C. E., Ibrahim, H. F., Iodice, M., Jiang, X., Kaufman, L. J., Kino, K., Kross, B., Lagamba, L., LeRose, J. J., Lindgren, R. A., Lucentini, M., Margaziotis, D. J., Markowitz, P., Meziani, Z. E., McCormick, K., Michaels, R. W., Millener, D. J., Miyoshi, T., Moffit, B., Monaghan, P. A., Moteabbed, M., Camacho, C. Munoz, Nanda, S., Nappi, E., Nelyubin, V. V., Norum, B. E., Okasyasu, Y., Paschke, K. D., Perdrisat, C. F., Piasetzky, E., Punjabi, V. A., Qiang, Y., Reimer, P. E., Reinhold, J., Reitz, B., Roche, R. E., Rodriguez, V. M., Saha, A., Santavenere, F., Sarty, A. J., Segal, J., Shahinyan, A., Singh, J., Sirca, S., Snyder, R., Solvignon, P. H., Sotona, M., Subedi, R., Sulkosky, V. A., Suzuki, T., Ueno, H., Ulmer, P. E., Veneroni, P., Voutier, E., Wojtsekhowski, B. B., Zheng, X., Zorn, C., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), HALL A, and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

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. The cross section to low-lying states of Lambda-9Li is concentrated within 3 MeV of the ground state and can be fitted with four peaks. The positions of the doublets agree with theory while a disagreement could exist with respect to the relative strengths of the peaks in the doublets. A Lambda separation energy of 8.36 +- 0.08 (stat.) +- 0.08 (syst.) MeV was measured, in agreement with an earlier experiment., Comment: 14 pages, 8 figures

Published
2015

8. Neutral B-meson mixing parameters in and beyond the SM with 2+1 flavor lattice QCD

Author

Bouchard, C. M., Freeland, E. D., Bernard, C. W., Chang, C. C., El-Khadra, A. X., G��miz, M. E., Kronfeld, A. S., Laiho, J., and Van de Water, R. S.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Lattice, High Energy Physics::Lattice, High Energy Physics - Lattice (hep-lat), High Energy Physics::Phenomenology, FOS: Physical sciences, High Energy Physics::Experiment
Abstract

We report on the status of our calculation of the hadronic matrix elements for neutral $B$-meson mixing with asqtad sea and valence light quarks and using the Wilson clover action with the Fermilab interpretation for the $b$ quark. We calculate the matrix elements of all five local operators that contribute to neutral $B$-meson mixing both in and beyond the Standard Model. We use MILC ensembles with $N_f=2+1$ dynamical flavors at four different lattice spacings in the range $a \approx 0.045$--$0.12$~fm, and with light sea-quark masses as low as 0.05 times the physical strange quark mass. We perform a combined chiral-continuum extrapolation including the so-called wrong-spin contributions in simultaneous fits to the matrix elements of the five operators. We present a complete systematic error budget and conclude with an outlook for obtaining final results from this analysis., 7 pages, 4 figures, presented at the 32nd International Symposium on Lattice Field Theory (Lattice 2014), 23-28 June, 2014, Columbia University, New York, NY

Published
2014

9. Update on a short-distance D^0-meson mixing calculation with $N_f=2+1$ flavors

Author

Chang, C. C., Bernard, C., Bouchard, C. M., El-Khadra, A. X., Freeland, E. D., Gámiz, E., Kronfeld, A. S., Laiho, J., and Van de Water, R. S.

Subjects
High Energy Physics - Lattice, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, High Energy Physics - Lattice (hep-lat), FOS: Physical sciences, High Energy Physics::Experiment
Abstract

We present an update on our calculation of the short-distance $D^0$-meson mixing hadronic matrix elements. The analysis is performed on the MILC collaboration's $N_f=2+1$ asqtad configurations. We use asqtad light valence quarks and the Sheikoleslami-Wohlert action with the Fermilab interpretation for the valence charm quark. SU(3), partially quenched, rooted, staggered heavy-meson chiral perturbation theory is used to extrapolate to the chiral-continuum limit. Systematic errors arising from the chiral-continuum extrapolation, heavy-quark discretization, and quark-mass uncertainties are folded into the statistical errors from the chiral-continuum fits with methods of Bayesian inference. A preliminary error budget for all five operators is presented., Comment: 7 pages, 1 figure, LATTICE2014 proceedings

Published
2014
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10. Greenland Telescope Project --- Direct Confirmation of Black Hole with Sub-millimeter VLBI

Author

Inoue, M., Algaba-Marcos, J. C., Asada, K., Chang, C. -C., Chen, M. -T., Han, J., Hirashita, H., Ho, P. T. P., Hsieh, S. -N., Huang, T., Jiang, H., Koch, P. M., Kubo, D. Y., Kuo, C. -Y., Liu, B., Martin-Cocher, P., Matsushita, S., Meyer-Zhao, Z., Nakamura, M., Nishioka, H., Nystrom, G., Pradel, N., Pu, H. -Y., Raffin, P. A., Shen, H. -Y., Snow, W., Srinivasan, R., Wei, T. -S., Blundell, R., Burgos, R., Grimes, P., Keto, E., Paine, S., Patel, N., Sridharan, T. K., Doeleman, S. S., Fish, V., Brisken, W., and Napier, P.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, Active galactic nucleus, Astronomy, FOS: Physical sciences, Condensed Matter Physics, Submillimeter Array, law.invention, Telescope, Radio telescope, law, Very-long-baseline interferometry, General Earth and Planetary Sciences, Angular resolution, Millimeter, Electrical and Electronic Engineering, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM), Geology
Abstract

A 12-m diameter radio telescope will be deployed to the Summit Station in Greenland to provide direct confirmation of a Super Massive Black Hole (SMBH) by observing its shadow image in the active galaxy M87. The telescope (Greenland Telescope: GLT) is to become one of the Very Long Baseline Interferometry (VLBI) stations at sub-millimeter (submm) regime, providing the longest baseline > 9,000 km to achieve an exceptional angular resolution of 20 micro arc sec at 350 GHz, which will enable us to resolve the shadow size of ~40 micro arc sec. The triangle with the longest baselines formed by the GLT, the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and the Submillimeter Array (SMA) in Hawaii will play a key role for the M87 observations. We have been working on the image simulations based on realistic conditions for a better understanding of the possible observed images. In parallel, retrofitting of the telescope and the site developments are in progress. Based on three years of opacity monitoring at 225 GHz, our measurements indicate that the site is excellent for submm observations, comparable to the ALMA site. The GLT is also expected to make single-dish observations up to 1.5 THz., 15 pages, 6 figures, accepted by Radio Science journal

Published
2014
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11. Separated Response Functions in Exclusive, Forward $��^{\pm}$ Electroproduction on Deuterium

Author

Huber, G. M., Blok, H. P., Butuceanu, C., Gaskell, D., Horn, T., Mack, D. J., Abbott, D., Aniol, K., Anklin, H., Armstrong, C., Arrington, J., Assamagan, K., Avery, S., Baker, O. K., Barrett, B., Beise, E. J., Bochna, C., Boeglin, W., Brash, E. J., Breuer, H., Chang, C. C., Chant, N., Christy, M. E., Dunne, J., Eden, T., Ent, R., Fenker, H., Gibson, E. F., Gilman, R., Gustafsson, K., Hinton, W., Holt, R. J., Jackson, H., Jin, S., Jones, M. K., Keppel, C. E., Kim, P. H., Kim, W., King, P. M., Klein, A., Koltenuk, D., Kovaltchouk, V., Liang, M., Liu, J., Lolos, G. J., Lung, A., Margaziotis, D. J., Markowitz, P., Matsumura, A., McKee, D., Meekins, D., Mitchell, J., Miyoshi, T., Mkrtchyan, H., Mueller, B., Niculescu, G., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Pitz, D., Potterveld, D., Punjabi, V., Qin, L. M., Reimer, P. E., Reinhold, J., Roche, J., Roos, P. G., Sarty, A., Shin, I. K., Smith, G. R., Stepanyan, S., Tang, L. G., Tadevosyan, V., Tvaskis, V., van der Meer, R. L. J., Vansyoc, K., Van Westrum, D., Vidakovic, S., Volmer, J., Vulcan, W., Warren, G., Wood, S. A., Xu, C., Yan, C., Zhao, W. -X., Zheng, X., Zihlmann, B., and Collaboration, The Jefferson Lab Fpi

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, $Q^2$, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in $��^-$ and $��^+$ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Method: Data were acquired with 2.6-5.2 GeV electron beams and the HMS+SOS spectrometers in Jefferson Lab Hall C, at central $Q^2$ values of 0.6, 1.0, 1.6 GeV$^2$ at W=1.95 GeV, and $Q^2$=2.45 GeV$^2$ at W=2.22 GeV. There was significant coverage in $��$ and $��$, which allowed separation of $��_{L,T,LT,TT}$. Results: $��_L$ shows a clear signature of the pion pole, with a sharp rise at small -t. In contrast, $��_T$ is much flatter versus t. The longitudinal/transverse ratios evolve with $Q^2$ and t, and at the highest $Q^2$=2.45 GeV$^2$ show a slight enhancement for $��^-$ production compared to $��^+$. The $��^-/��^+$ ratio for transverse photons exhibits only a small $Q^2$-dependence, following a nearly universal curve with t, with a steep transition to a value of about 0.25, consistent with s-channel quark knockout. The $��_{TT}/��_T$ ratio also drops rapidly with $Q^2$, qualitatively consistent with s-channel helicity conservation. The $��^-/��^+$ ratio for longitudinal photons indicates a small isoscalar contamination at W=1.95 GeV, consistent with what was observed in our earlier determination of the pion form factor at these kinematics., 25 pages, 16 figures, 6 tables

Published
2014
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12. Guiding center orbit following calculation of edge particle and heat transport in stochastic magnetic field

Author

Chang, C. C., Nishimura, Y., and Cheng, C. Z.

Subjects
Plasma Physics (physics.plasm-ph), FOS: Physical sciences, equipment and supplies, human activities, Physics - Plasma Physics
Abstract

Particle and heat transport in tokamak edge is investigated by guiding center orbit following calculation. The guiding center equation is solved for both electrons and ions in the presence of magnetic perturbation. It is suggested that the remnants of the magnetic islands play a role in characterizing the radial transport. The transport coefficient is estimated which also demonstrate local structure in the vicinity of magnetic islands.

Published
2013

13. Matrix Elements for $D$- and $B$-Mixing from 2+1 Flavor Lattice QCD

Author

Chang, C. C., Bernard, C., Chris Bouchard, El-Khadra, A. X., Freeland, E. D., Gámiz, E., Kronfeld, A. S., Laiho, J., and Water, R. S.

Subjects
High Energy Physics - Lattice, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, High Energy Physics - Lattice (hep-lat), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract

We present the status of our calculation of hadronic matrix elements for $D$- and $B$-meson mixing. We use a large set of the MILC collaboration's $N_f=2+1$ asqtad ensembles, which includes lattice spacings in the range $a\approx0.12$-0.045 fm, and up/down to strange quark mass ratios as low as 0.05. The asqtad action is also employed for the light valence quarks. For the heavy quarks we use the Sheikholeslami-Wohlert action with the Fermilab interpretation. Our calculation covers the complete set of five local operators needed to describe $B$-meson mixing in the Standard Model and Beyond. In the charm sector, our calculation of local mixing matrix elements may be used to constrain new physics models. We present final correlator fit results on the full data set for the $B$-meson mixing project and preliminary fit results for the $D$-meson mixing project., Comment: 7 pages, 4 figures, Lattice 2013 proceedings

Published
2013
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14. Moments of the neutron $g_2$ structure function at intermediate $Q^2$

Author

Solvignon, P., Liyanage, N., Chen, J. -P., Choi, Seonho, Slifer, K., Aniol, K., Averett, T., Boeglin, W., Camsonne, A., Cates, G. D., Chang, C. C., Chudakov, E., Craver, B., Cusanno, F., Deur, A., Dutta, D., Ent, R., Feuerbach, R., Frullani, S., Gao, H., Garibaldi, F., Gilman, R., Glashausser, C., Gorbenko, V., Hansen, O., Higinbotham, D. W., Ibrahim, H., Jiang, X., Jones, M., Kelleher, A., Kelly, J., Keppel, C., Kim, W., Korsch, W., Kramer, K., Kumbartzki, G., LeRose, J. J., Lindgren, R., Ma, B., Margazioti, D. J., Markowitz, P., McCormick, K., Meziani, Z. -E., Michaels, R., Moffit, B., Monaghan, P., Camacho, C. Munoz, Paschke, K., Reitz, B., Saha, A., Shneor, R., Singh, J., Sulkosky, V., Tobias, A., Urciuoli, G. M., Wang, K., Wijesooriya, K., Wojtsekhowski, B., Woo, S., Yang, J. -C., Zheng, X., and Zhu, L.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

We present new experimental results of the $^3$He spin structure function $g_2$ in the resonance region at $Q^2$ values between 1.2 and 3.0 (GeV/c)$^2$. Spin dependent moments of the neutron were then extracted. Our main result, the resonance contribution to the neutron $d_2$ matrix element, was found to be small at $$=2.4 (GeV/c)$^2$ and in agreement with the Lattice QCD calculation. The Burkhardt-Cottingham sum rule for $^3$He and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low $x$ unmeasured region. A small deviation was observed at $Q^2$ values between 0.5 and 1.2 (GeV/c)$^2$ for the neutron.

Published
2013
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15. Interfacial Instabilities in Torsional Flows

Author

Lai, C. -Y., Sun, Y. -T, Chang, C. -C., Chen, Y. -Y., Arratia, P. E., and Tsai, J. -C.

Subjects
Fluid Dynamics (physics.flu-dyn), FOS: Physical sciences, Physics - Fluid Dynamics
Abstract

In this fluid dynamics video, we show current findings on the morphology of an oil-water interface in a torsional flow produced by rotating the upper lid of a cylindrical tank. This video was submitted as part of the Gallery of Fluid Motion 2012 which is showcase of fluid dynamics videos., 1 video is included

Published
2012

16. Measurement of the gradient of the Casimir force between a nonmagnetic sphere and a magnetic plate

Author

Banishev, A. A., Chang, C. -C., Klimchitskaya, G. L., Mostepanenko, V. M., and Mohideen, U.

Subjects
Condensed Matter - Other Condensed Matter, Condensed Matter::Materials Science, Quantum Physics, FOS: Physical sciences, Condensed Matter::Strongly Correlated Electrons, Quantum Physics (quant-ph), Other Condensed Matter (cond-mat.other)
Abstract

We measured the gradient of the Casimir force between an Au sphere and a plate made of ferromagnetic metal (Ni). It is demonstrated that the magnetic properties influence the force magnitude. This opens prospective opportunities for the control of the Casimir force in nanotechnology and for obtaining Casimir repulsion by using ferromagnetic dielectrics., 15 pages, 4 figures, to appear in Phys. Rev. B

Published
2012

17. Virtual Compton Scattering and the Generalized Polarizabilities of the Proton at Q^2=0.92 and 1.76 GeV^2

Author

Fonvieille, H., Laveissiere, G., Degrande, N., Jaminion, S., Jutier, C., Todor, L., Di Salvo, R., Van Hoorebeke, L., Alexa, L. C., Anderson, B. D., Aniol, K. A., Arundell, K., Audit, G., Auerbach, L., Baker, F. T., Baylac, M., Berthot, J., Bertin, P. Y., Bertozzi, W., Bimbot, L., Boeglin, W. U., Brash, E. J., Breton, V., Breuer, H., Burtin, E., Calarco, J. R., Cardman, L. S., Cavata, C., Chang, C. -C., Chen, J. -P., Chudakov, E., Cisbani, E., Dale, D. S., deJager, C. W., De Leo, R., Deur, A., d'Hose, N., Dodge, G. E., Domingo, J. J., Elouadrhiri, L., Epstein, M. B., Ewell, L. A., Finn, J. M., Fissum, K. G., Fournier, G., Frois, B., Frullani, S., Furget, C., Gao, H., Gao, J., Garibaldi, F., Gasparian, A., Gilad, S., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Gorbenko, V., Grenier, P., Guichon, P. A. M., Hansen, J. O., Holmes, R., Holtrop, M., Howell, C., Huber, G. M., Hyde, C. E., Incerti, S., Iodice, M., Jardillier, J., Jones, M. K., Kahl, W., Kato, S., Katramatou, A. T., Kelly, J. J., Kerhoas, S., Ketikyan, A., Khayat, M., Kino, K., Kox, S., Kramer, L. H., Kumar, K. S., Kumbartzki, G., Kuss, M., Leone, A., LeRose, J. J., Liang, M., Lindgren, R. A., Liyanage, N., Lolos, G. J., Lourie, R. W., Madey, R., Maeda, K., Malov, S., Manley, D. M., Marchand, C., Marchand, D., Margaziotis, D. J., Markowitz, P., Marroncle, J., Martino, J., McCormick, K., McIntyre, J., Mehrabyan, S., Merchez, F., Meziani, Z. E., Michaels, R., Miller, G. W., Mougey, J. Y., Nanda, S. K., Neyret, D., Offermann, E. A. J. M., Papandreou, Z., Pasquini, B., Perdrisat, C. F., Perrino, R., Petratos, G. G., Platchkov, S., Pomatsalyuk, R., Prout, D. L., Punjabi, V. A., Pussieux, T., Quemener, G., Ransome, R. D., Ravel, O., Real, J. S., Renard, F., Roblin, Y., Rowntree, D., Rutledge, G., Rutt, P. M., Saha, A., Saito, T., Sarty, A. J., Serdarevic, A., Smith, T., Smirnov, G., Soldi, K., Sorokin, P., Souder, P. A., Suleiman, R., Templon, J. A., Terasawa, T., Tieulent, R., Tomasi-Gustaffson, E., Tsubota, H., Ueno, H., Ulmer, P. E., Urciuoli, G. M., Vanderhaeghen, M., Van der Meer, R. L. J., Van De Vyver, R., Vernin, P., Vlahovic, B., Voskanyan, H., Voutier, E., Watson, J. W., Weinstein, L. B., Wijesooriya, K., Wilson, R., Wojtsekhowski, B. B., Zainea, D. G., Zhang, W. -M., Zhao, J., Zhou, Z. -L., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
High Energy Physics - Experiment (hep-ex), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, High Energy Physics - Experiment
Abstract

Virtual Compton Scattering (VCS) on the proton has been studied at Jefferson Lab using the exclusive photon electroproduction reaction (e p --> e p gamma). This paper gives a detailed account of the analysis which has led to the determination of the structure functions P_LL-P_TT/epsilon and P_LT, and the electric and magnetic generalized polarizabilities (GPs) alpha_E(Q^2) and beta_M(Q^2) at values of the four-momentum transfer squared Q^2= 0.92 and 1.76 GeV^2. These data, together with the results of VCS experiments at lower momenta, help building a coherent picture of the electric and magnetic GPs of the proton over the full measured Q^2-range, and point to their non-trivial behavior., version 2: modified according to PRC Editor's and Referee's recommendations. Archival paper for the E93-050 experiment at JLab Hall A. 28 pages, 23 figures, 5 cross-section tables. To be submitted to Phys.Rev.C

Published
2012

18. Final Analysis of Proton Form Factor Ratio Data at $\mathbf{Q^2 = 4.0}$, 4.8 and 5.6 GeV$\mathbf{^2}$

Author

Puckett, A. J. R., Brash, E. J., Gayou, O., Jones, M. K., Pentchev, L., Perdrisat, C. F., Punjabi, V., Aniol, K. A., Averett, T., Benmokhtar, F., Bertozzi, W., Bimbot, L., Calarco, J. R., Cavata, C., Chai, Z., Chang, C. -C., Chang, T., Chen, J. P., Chudakov, E., de Leo, R., Dieterich, S., Endres, R., Epstein, M. B., Escoffier, S., Fonvieille, H., Frullani, S., Gao, J., Garibaldi, F., Gilad, S., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Hansen, J. -O., Higinbotham, D., Huber, G. M., Iodice, M., de Jager, C. W., Jiang, X., Khandaker, M., Kozlov, S., Kramer, K. M., Kumbartzki, G., Lerose, J. J., Lhuillier, D., Lindgren, R. A., Liyanage, N., Lolos, G. J., Margaziotis, D. J., Marie, F., Markowitz, P., Mccormick, K., Michaels, R., Milbrath, B. D., Nanda, S. K., Neyret, D., Piskunov, N. M., Ransome, R. D., Raue, B. A., Roché, R., Rvachev, M., Saha, A., Salgado, C., Sirca, S., Sitnik, I., Strauch, S., Todor, L., Tomasi-Gustafsson, E., Urciuoli, G. M., Voskanyan, H., Wijesooriya, K., Wojtsekhowski, B. B., Zheng, X., Zhu, L., Fissum, K.G., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Département d'Electronique, des Détecteurs et d'Informatique pour la Physique (ex SEDI) (DEDIP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, HALL A, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
High Energy Physics - Experiment (hep-ex), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, High Energy Physics - Experiment
Abstract

Precise measurements of the proton electromagnetic form factor ratio $R = \mu_p G_E^p/G_M^p$ using the polarization transfer method at Jefferson Lab have revolutionized the understanding of nucleon structure by revealing the strong decrease of $R$ with momentum transfer $Q^2$ for $Q^2 \gtrsim 1$ GeV$^2$, in strong disagreement with previous extractions of $R$ from cross section measurements. In particular, the polarization transfer results have exposed the limits of applicability of the one-photon-exchange approximation and highlighted the role of quark orbital angular momentum in the nucleon structure. The GEp-II experiment in Jefferson Lab's Hall A measured $R$ at four $Q^2$ values in the range 3.5 GeV$^2 \le Q^2 \le 5.6$ GeV$^2$. A possible discrepancy between the originally published GEp-II results and more recent measurements at higher $Q^2$ motivated a new analysis of the GEp-II data. This article presents the final results of the GEp-II experiment, including details of the new analysis, an expanded description of the apparatus and an overview of theoretical progress since the original publication. The key result of the final analysis is a systematic increase in the results for $R$, improving the consistency of the polarization transfer data in the high-$Q^2$ region. This increase is the result of an improved selection of elastic events which largely removes the systematic effect of the inelastic contamination, underestimated by the original analysis., Comment: 30 pages, 17 figures, 4 tables. Final version to appear in Phys. Rev. C

Published
2011

19. Magnetodielectric study in SiO2-coated Fe3O4 nanoparticle compacts

Author

Chang, C. -C., Zhao, L., and Wu, M. -K.

Subjects
Condensed Matter - Materials Science, Condensed Matter::Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Physics::Optics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

The dielectric properties of Fe$_{3}$O$_{4}$ magnetic nanoparticles with an insulating coating layer of SiO$_{2}$ were investigated. At high temperatures, the changes of the dielectric constant and loss induced by the magnetic field are opposite in sign and strongly frequency-dependent, which originates from extrinsic magnetodielectric coupling-the Maxwell-Wagner effect combined with magnetoresistance. And the interface defects leads to the obvious hysteresis phenomena observed in the measurements. On the other hand, the strong coupling of dielectric and magnetic properties at low temperatures contradicts the Maxwell-Wagner model, suggesting the intrinsic magnetodielectric coupling. Our observations are consistent with the recent polarization switching measurements, which confirm the low-temperature multiferroic state existing in highly-lossy Fe$_{3}$O$_{4}$. And the core/shell nanostructure may provide a new route to achieve applicable magnetoelectric materials with low loss., Comment: 6 pages, 6 figures, published in Journal of Applied Physics

Published
2011
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20. Charged pion form factor between Q^2=0.60 and 2.45 GeV^2. II. Determination of, and results for, the pion form factor

Author

Huber, G. M., Blok, H. P., Horn, T., Beise, E. J., Gaskell, D., Mack, D. J., Tadevosyan, V., Volmer, J., Abbott, D., Aniol, K., Anklin, H., Armstrong, C., Arrington, J., Assamagan, K., Avery, S., Baker, O. K., Barrett, B., Bochna, C., Boeglin, W., Brash, E. J., Breuer, H., Chang, C. C., Chant, N., Christy, M. E., Dunne, J., Eden, T., Ent, R., Gibson, E., Gilman, R., Gustafsson, K., Hinton, W., Holt, R. J., Jackson, H., Jin, S., Jones, M. K., Keppel, C. E., Kim, P. H., Kim, W., King, P. M., Klein, A., Koltenuk, D., Kovaltchouk, V., Kiang, M., Liu, J., Lolos, G. J., Lung, A., Margaziotis, D. J., Markowitz, P., Matsumura, A., McKee, D., Meekins, D., Mitchell, J., Miyoshi, T., Mkrtchyan, H., Mueller, B., Niculescu, G., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Pitz, D., Potterveld, D., Punjabi, V., Qin, L. M., Reimer, P., Reinhold, J., Roche, J., Roos, P. G., Sarty, A., Shin, I. K., Smith, G. R., Stepanyan, S., Tang, L. G., Tvaskis, V., van der Meer, R. L. J., Vansyoc, K., Van Westrum, D., Vidakovic, S., Vulcan, W., Warren, G., Wood, S. A., Xu, C., Yan, C., Zhao, W. -X., Zheng, X., and Zihlmann, B.

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The charged pion form factor, Fpi(Q^2), is an important quantity which can be used to advance our knowledge of hadronic structure. However, the extraction of Fpi from data requires a model of the 1H(e,e'pi+)n reaction, and thus is inherently model dependent. Therefore, a detailed description of the extraction of the charged pion form factor from electroproduction data obtained recently at Jefferson Lab is presented, with particular focus given to the dominant uncertainties in this procedure. Results for Fpi are presented for Q^2=0.60-2.45 GeV^2. Above Q^2=1.5 GeV^2, the Fpi values are systematically below the monopole parameterization that describes the low Q^2 data used to determine the pion charge radius. The pion form factor can be calculated in a wide variety of theoretical approaches, and the experimental results are compared to a number of calculations. This comparison is helpful in understanding the role of soft versus hard contributions to hadronic structure in the intermediate Q^2 regime., 18 pages, 11 figures

Published
2008

21. Charged pion form factor between $Q^2$=0.60 and 2.45 GeV$^2$. I. Measurements of the cross section for the ${^1}$H($e,e'��^+$)$n$ reaction

Author

Blok, H. P., Horn, T., Huber, G. M., Beise, E. J., Gaskell, D., Mack, D. J., Tadevosyan, V., Volmer, J., Abbott, D., Aniol, K., Anklin, H., Armstrong, C., Arrington, J., Assamagan, K., Avery, S., Baker, O. K., Barrett, B., Bochna, C., Boeglin, W., Brash, E. J., Breuer, H., Chang, C. C., Chant, N., Christy, M. E., Dunne, J., Eden, T., Ent, R., Fenker, H., Gibson, E., Gilman, R., Gustafsson, K., Hinton, W., Holt, R. J., Jackson, H., Jin, S., Jones, M. K., Keppel, C. E., Kim, P. H., Kim, W., King, P. M., Klein, A., Koltenuk, D., Kovaltchouk, V., Liang, M., Liu, J., Lolos, G. J., Lung, A., Margaziotis, D. J., Markowitz, P., Matsumura, A., McKee, D., Meekins, D., Mitchell, J., Miyoshi, T., Mkrtchyan, H., Mueller, B., Niculescu, G., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Pitz, D., Potterveld, D., Punjabi, V., Qin, L. M., Reimer, P., Reinhold, J., Roche, J., Roos, P. G., Sarty, A., Shin, I. K., Smith, G. R., Stepanyan, S., Tang, L. G., Tvaskis, V., van der Meer, R. L. J., Vansyoc, K., Van Westrum, D., Vidakovic, S., Vulcan, W., Warren, G., Wood, S. A., Xu, C., Yan, C., Zhao, W. -X., Zheng, X., and Zihlmann, B.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

Cross sections for the reaction ${^1}$H($e,e'��^+$)$n$ were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the CEBAF high-intensity, continous electron beam in order to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from $Q^2$=0.60 to 2.45 GeV$^2$ at an invariant mass of the virtual photon-nucleon system of $W$=1.95 and 2.22 GeV. The measured cross sections were separated into the four structure functions $��_L$, $��_T$, $��_{LT}$, and $��_{TT}$. The various parts of the experimental setup and the analysis steps are described in detail, including the calibrations and systematic studies, which were needed to obtain high precision results. The different types of systematic uncertainties are also discussed. The results for the separated cross sections as a function of the Mandelstam variable $t$ at the different values of $Q^2$ are presented. Some global features of the data are discussed, and the data are compared with the results of some model calculations for the reaction ${^1}$H($e,e'��^+$)$n$., 26 pages, 23 figures

Published
2008
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22. High Resolution Spectroscopy of 16N_Lambda by Electroproduction

Author

Cusanno, F., Urciuoli, G. M., Acha, A., Ambrozewicz, P., Aniol, K. A., Baturin, P., Bertin, P.Y., Benaoum, H., Blomqvist, K. I., Boeglin, W. U., Breuer, H., Brindza, P., Bydzovsky, P., Camsonne, A., Chang, C. C., Chen, J. -P., Choi, Seonho, Chudakov, E. A., Cisbani, E., Colilli, S., Coman, L., Craver, B. J., De Cataldo, G., De Jager, C. W., De Leo, R., Deur, A. P., Ferdi, C., Feuerbach, R. J., Folts, E., Fratoni, R., Frullani, S., Garibaldi, F., Gayou, O., Giuliani, F., Gomez, J., Gricia, M., Hansen, J. O., Hayes, D., Higinbotham, D. W., Holmstrom, T. K., Hyde, C. E., Ibrahim, H. F., Iodice, M., Jiang, X., Kaufman, L. J., Kino, K., Kross, B., Lagamba, L., Lerose, J. J., Lindgren, R. A., Lucentini, M., Margaziotis, D. J., Markowitz, P., Marrone, S., Meziani, Z. E., McCormick, K., Michaels, R. W., Millener, D. J., Miyoshi, T., Moffit, B., Monaghan, P. A., Moteabbed, M., Muñoz Camacho, C., Nanda, S., Nappi, E., Nelyubin, V. V., Norum, B. E., Okasyasu, Y., Paschke, K. D., Perdrisat, C. F., Piasetzky, E., Punjabi, V. A., Qiang, Y., Raue, B., Reimer, P. E., Reinhold, J., Reitz, B., Roche, R. E., Rodriguez, V. M., Saha, A., Santavenere, F., Sarty, A. J., Segal, J., Shahinyan, A., Singh, J., Sirca, S., Snyder, R., Solvignon, P. H., Sotona, M., Subedi, R., Sulkosky, V. A., Suzuki, T., Ueno, H., Ulmer, P. E., Veneroni, P., Voutier, E., Wojtsekhowski, B. B., Zeng, X., Zorn, C., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), HALL A, and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

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. A ground-state binding energy of 13.76 +/- 0.16 MeV was obtained for 16N_Lambda with better precision than previous measurements on the mirror hypernucleus 16O_Lambda. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p_{1/2} and p_{3/2} hole states of the 15N core nucleus., Comment: 5 pages, 3 figures, 2 tables

Published
2008
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23. Experimental approaches to the difference in the Casimir force through the varying optical properties of boundary surface

Author

Castillo-Garza, R., Chang, C. -C., Jimenez, D., Klimchitskaya, G. L., Mostepanenko, V. M., and Mohideen, U.

Subjects
Quantum Physics, FOS: Physical sciences, Quantum Physics (quant-ph)
Abstract

We propose two novel experiments on the measurement of the Casimir force acting between a gold coated sphere and semiconductor plates with markedly different charge carrier densities. In the first of these experiments a patterned Si plate is used which consists of two sections of different dopant densities and oscillates in the horizontal direction below a sphere. The measurement scheme in this experiment is differential, i.e., allows the direct high-precision measurement of the difference of the Casimir forces between the sphere and sections of the patterned plate or the difference of the equivalent pressures between Au and patterned parallel plates with static and dynamic techniques, respectively. The second experiment proposes to measure the Casimir force between the same sphere and a VO${}_2$ film which undergoes the insulator-metal phase transition with the increase of temperature. We report the present status of the interferometer based variable temperature apparatus developed to perform both experiments and present the first results on the calibration and sensitivity. The magnitudes of the Casimir forces and pressures in the experimental configurations are calculated using different theoretical approaches to the description of optical and conductivity properties of semiconductors at low frequencies proposed in the literature. It is shown that the suggested experiments will aid in the resolution of theoretical problems arising in the application of the Lifshitz theory at nonzero temperature to real materials. They will also open new opportunities in nanotechnology., Comment: 23 pages of the text, 2 tables, and captions of 12 figures (to appear in Phys. Rev. A)

Published
2007
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24. Determination of the Charged Pion Form Factor at Q2=1.60 and 2.45 (GeV/c)2

Author

Fpi2 collaboration, Horn, T., Aniol, K., Arrington, J., Barrett, B., Beise, E. J., Blok, H. P., Boeglin, W., Brash, E. J., Breuer, H., Chang, C. C., Christy, M. E., Ent, R., Gaskell, D., Gibson, E., Holt, R. J., Huber, G. M., Jin, S., Jones, M. K., Keppel, C. E., Kim, W., King, P. M., Kovaltchouk, V., Liu, J., Lolos, G. J., Mack, D. J., Margaziotis, D. J., Markowitz, P., Matsumura, A., Meekins, D., Miyoshi, T., Mkrtchyan, H., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Potterveld, D., Punjabi, V., Reimer, P., Reinhold, J., Roche, J., Roos, P. G., Sarty, A., Smith, G. R., Tadevosyan, V., Tang, L. G., Tvaskis, V., Vidakovic, S., Volmer, J., Vulcan, W., Warren, G., Wood, S. A., Xu, C., and Zheng, X.

Subjects
High Energy Physics::Lattice, Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F_pi) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F_pi is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative Quantum Chromo-Dynamics prediction., Comment: 4 pages, 3 figures, submitted to Physical Review Letters

Published
2006
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25. Proton elastic form factor ratios to $Q^2$=3.5 GeV$^2$ by polarization transfer

Author

Punjabi, V., Perdrisat, C.F., Aniol, K.A., Baker, F.T., Berthot, J., Bertin, P.Y., Bertozzi, W., Besson, A., Bimbot, L., Boeglin, W.U., Brash, E.J., Brown, D., Calarco, J.R., Cardman, L.S., Chai, Z., Chang, C.-C., Chen, J.-P., Chudakov, E., Churchwell, S., Cisbani, E., Dale, D.S., De Leo, R., Deur, A., Diederich, B., Domingo, J.J., Epstein, M.B., Ewell, L.A., G. Fissum, K., Fleck, A., Fonvieille, H., Frullani, S., Gao, J., Garibaldi, F., Gasparian, A., Gerstner, G., Gilad, S., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Gorbenko, V., Green, A., Hansen, J.-O., Howell, C.R., Huber, G.M., Iodice, M., De Jager, C.W., Jaminion, S., Jiang, X., Jones, M.K., Kahl, W., Kelly, J.J., Khayat, M., Kramer, L.H., Kumbartzki, G., Kuss, M., Lakuriki, E., Laveissière, G., LeRose, J.J., Liang, M., Lindgren, R.A., Liyanage, N., Lolos, G.J., Macri, R., Madey, R., Malov, S., Margaziotis, D.J., Markowitz, P., McCormick, K., McIntyre, J.I., Van Der Meer, R.L.J., Michaels, R., Milbrath, B.D., Mougey, J.Y., Nanda, S.K., Offermann, E.A.J.M., Papandreou, Z., Pentchev, L., Petratos, G.G., Piskunov, N.M., Pomatsalyuk, R.I., Prout, D.L., Quéméner, G., Ransome, R.D., Raue, B.A., Roblin, Y., Roche, R., Rutledge, G., Rutt, P.M., Saha, A., Saito, T., Sarty, A.J., Smith, T.P., Sorokin, P., Strauch, S., Suleiman, R., Takahashi, K., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Vernin, P., Vlahovic, B., Voskanyan, H., Wijesooriya, K., Wojtsekhowski, B.B., Woo, R.J., Xiong, F., Zainea, G.D., Zhou, Z.-L., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), HALL A, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
electron-proton scattering, protons, polarisation in elementary particle interactions, electromagnetic form factors, FOS: Physical sciences, 25.30.Bf, 13.40.Gp, 24.85.+p, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

The ratio of the proton elastic electromagnetic form factors, $G_{Ep}/G_{Mp}$, was obtained by measuring $P_{t}$ and $P_{\ell}$, the transverse and longitudinal recoil proton polarization components, respectively, for the elastic $\vec e p \to e\vec p$ ~reaction in the four-momentum transfer squared range of 0.5 to 3.5 GeV$^2$. In the single-photon exchange approximation, the ratio $G_{Ep}/G_{Mp}$ is directly proportional to the ratio $P_t/P_{\ell}$. The simultaneous measurement of $P_{t}$ and $P_{\ell}$ in a polarimeter reduces systematic uncertainties. The results for the ratio $G_{Ep}/G_{Mp}$ show a systematic decrease with increasing $Q^2$, indicating for the first time a definite difference in the distribution of charge and magnetization in the proton. The data have been re-analyzed and systematic uncertainties have become significantly smaller than previously published results., Comment: 31 pages, 29 gfigures, submitted to Phys. Rev. C

Published
2005

26. New measurement of parity violation in elastic electron-proton scattering and implications for strange form factors

Author

Aniol, K. A., Armstrong, D. S., Averett, T., Baylac, M., Burtin, E., Calarco, J., Cates, G. D., Cavata, C., Chai, Z., Chang, C. C., P Chen, J., Chudakov, E., Cisbani, E., Coman, M., Dale, D., Deur, A., Djawotho, P., Epstein, M. B., Stephanie Escoffier, Ewell, L., Falletto, N., Finn, J. M., Fleck, A., Frois, B., Frullani, S., Gao, J., Garibaldi, F., Gasparian, A., Gerstner, G. M., Gilman, R., Glamazdin, A., Gomez, J., Gorbenko, V., Hansen, O., Hersman, F., Higinbotham, D. W., Holmes, R., Holtrop, M., Humensky, B., Incerti, S., Iodice, M., Jager, C. W., Jardillier, J., Jiang, X., Jones, M. K., Jorda, J., Jutier, C., Kahl, W., Kelly, J. J., Kim, D. H., J Kim, M., Kim, M. S., Kominis, I., Kooijman, E., Kramer, K., Kumar, K. S., Kuss, M., Lerose, J., Leo, R., Leuschner, M., Lhuillier, D., Liang, M., Liyanage, N., Lourie, R., Madey, R., Malov, S., Margaziotis, D. J., Marie, F., Markowitz, P., Martino, J., Mastromarino, P., Mccormick, K., Mcintyre, J., E Meziani, Z., Michaels, R., Milbrath, B., Miller, G. W., Mitchell, J., Morand, L., Neyret, D., Petratos, G. G., Pomatsalyuk, R., Price, J. S., Prout, D., Pussieux, T., Quéméner, G., Ransome, R. D., Relyea, D., Roblin, Y., Roche, J., Rutledge, G. A., Rutt, P. M., Rvachev, M., Sabatie, F., Saha, A., Souder, P. A., Spradlin, M., Strauch, S., Suleiman, R., Templon, J., Teresawa, T., Thompson, J., Tieulent, R., Todor, L., Tonguc, B. T., Ulmer, P. E., Urciuoli, G. M., Vlahovic, B., Wijesooriya, K., Wilson, R., Wojtsekhowski, B., Woo, R., Wei-Jiang Xu, Younus, I., Zhang, C., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HAPPEX, and Chadelas, Michèle

Subjects
Elastic scattering, Physics, Nuclear and High Energy Physics, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], 010308 nuclear & particles physics, media_common.quotation_subject, Electroweak interaction, FOS: Physical sciences, Polarimeter, Parity (physics), Electron, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Cathode ray, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, media_common
Abstract

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees and Q^2 = 0.477 (GeV/c)^2. The measurement implies that the value for the strange form factor (G_E^s + 0.392 G_M^s) = 0.025 +- 0.020 +- 0.014, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a `strained' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization., 8 pages, 4 figures, Tex, elsart.cls; revised version as accepted for Phys. Lett. B

Published
2001

27. Quasielastic 12C(e,e'p) Reaction at High Momentum Transfer

Author

Morrison, J. H., Baghaei, H., Bertozzi, W., Gilad, S., Glickman, J., Hyde-Wright, C. E., Kalantar-Nayestanaki, N., Lourie, R. W., Penn, S., Ulmer, P. E., Weinstein, L. B., Cottman, B. H., Ghedira, L., Winhold, E. J., Calarco, J. R., Wise, J., Boberg, P., Chang, C. C., Zhang, D., Aniol, K., Epstein, M. B., Margaziotis, D. J., Finn, J. M., Perdrisat, C., and Punjabi, V.

Subjects
Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

We measured the 12C(e,e'p) cross section as a function of missing energy in parallel kinematics for (q,w) = (970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At w=475 MeV, at the maximum of the quasielastic peak, there is a large continuum (E_m > 50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50% of the measured cross section. The ratio of data to DWIA calculation is 0.4 for both the p- and s-shells. At w=330 MeV, well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the p-shell and 1.0 for the s-shell. We infer that one or more mechanisms that increase with $\omega$ transform some of the single-nucleon-knockout into multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section., Comment: 14 pages, 7 figures, Revtex (multicol, prc and aps styles), to appear in Phys Rev C

Published
1998

28. First M87 Event Horizon Telescope Results. I. the Shadow of the Supermassive Black Hole

Author

Olivier Gentaz, David J. James, Hector Olivares, John E. Barrett, Alan P. Marscher, C. M. Violette Impellizzeri, Peter Oshiro, Peter Galison, Tyler Trent, Sang-Sung Lee, Arturo I. Gómez-Ruiz, Satoki Matsushita, Carsten Kramer, Scott Paine, Dimitrios Psaltis, Mareki Honma, Kazi L.J. Rygl, Shuo Zhang, Jan Wagner, Daniel P. Marrone, Ryan Chilson, Jorge A. Preciado-López, Christopher Beaudoin, Sara Issaoun, André Young, A. A. Stark, Jordy Davelaar, Hiroshi Nagai, Zhiqiang Shen, Pablo Torne, Chris Eckert, John Wardle, Ranjani Srinivasan, David M. Gale, David Ball, Alan L. Roy, Lupin C.C. Lin, Thomas Bronzwaer, Kazunori Akiyama, W. B. Everett, Li Ming Lu, Ta Shun Wei, Sheperd S. Doeleman, Shu Hao Chang, Roberto Garcia, Richard L. Plambeck, Maciek Wielgus, Iniyan Natarajan, Raquel Fraga-Encinas, Hiroaki Nishioka, Mark G. Rawlings, Tirupati K. Sridharan, Geoffrey B. Crew, Vernon Fath, Michael H. Hecht, Frederic Gueth, Jun Yi Koay, David Sánchez-Arguelles, Chih Chiang Han, Michael Kramer, Mariafelicia De Laurentis, Kuo Liu, Oliver Porth, Jae-Young Kim, Ilje Cho, Shan Shan Zhao, Hotaka Shiokawa, Martin P. McColl, Song Chu Chang, Lei Huang, William Stahm, Makoto Inoue, Svetlana G. Jorstad, Andrew Chael, Chih Cheng Chang, Thomas P. Krichbaum, Dominic W. Pesce, Chung Chen Chen, Laura Vertatschitsch, Jonathan Weintroub, Alejandro F. Sáez-Madain, Sera Markoff, Shuichiro Tsuda, Ryan Berthold, Chao-Te Li, M. C. H. Wright, Daniel R. van Rossum, J. Peñalver, Neal R. Erickson, Remo P. J. Tilanus, John E. Carlstrom, Roger Deane, Minfeng Gu, Michael Titus, Laurent Loinard, Lia Medeiros, C. Y. Kuo, Iain Coulson, Michael Janssen, Ben Prather, Katherine L. Bouman, Lucy M. Ziurys, Norbert Wex, Freek Roelofs, Feng Gao, Yau De Huang, Dan Bintley, N. W. Halverson, Benjamin R. Ryan, Nimesh A. Patel, Aaron Faber, Mansour Karami, Robert Freund, Ming-Tang Chen, K. T. Story, Gertie Geertsema, Daryl Haggard, Paul Shaw, Ronald Grosslein, S. A. Dzib, Joseph Crowley, Kuo Chang Han, Shoko Koyama, José L. Gómez, Chet Ruszczyk, David R. Smith, Michael Bremer, Daniel Michalik, James Hoge, Karl M. Menten, Juan-Carlos Algaba, Aristeidis Noutsos, William Snow, Thomas W. Folkers, Masanori Nakamura, Homin Jiang, James M. Cordes, Uwe Bach, Christopher Risacher, Rurik A. Primiani, Pierre Christian, David H. Hughes, Wen Ping Lo, Geoffrey C. Bower, James M. Moran, Ciriaco Goddi, Yi Chen, Christopher Greer, Roger J. Cappallo, Ilse van Bemmel, Andreas Eckart, Ziyan Zhu, Chi H. Nguyen, Rubén Herrero-Illana, Robert Wharton, Antonio Hernández-Gómez, Bart Ripperda, Dominique Broguiere, Pim Schellart, Mark Derome, Chih-Wei Locutus Huang, Chen Yu Yu, Kuan Yu Liu, Lijing Shao, Christiaan D. Brinkerink, Michael D. Johnson, Mark Kettenis, Michael Lindqvist, Frederick K. Baganoff, John Conway, Remi Sassella, Nathan Whitehorn, Eduardo Ros, David P. Woody, Jessica Dempsey, Gopal Narayanan, Elisabetta Liuzzo, Akihiko Hirota, D. A. Graham, Hiroki Okino, Vincent Piétu, Alexander W. Raymond, Gregory Desvignes, Anne Kathrin Baczko, Arash Roshanineshat, Kevin M. Silva, Timothy Norton, Heino Falcke, Aleksandar Popstefanija, Ken H. Young, Per Friberg, Paul Yamaguchi, Derek Kubo, E. Castillo-Domínguez, Jason W. Henning, R. Laing, Kimihiro Kimura, Rodrigo Córdova Rosado, Roman Gold, Helge Rottmann, Silke Britzen, J. Anton Zensus, Roger Brissenden, Ru-Sen Lu, Ye-Fei Yuan, F. Peter Schloerb, Stephen R. McWhirter, Joseph R. Farah, Ue-Li Pen, Yosuke Mizuno, Charles F. Gammie, Mel Rose, Harriet Parsons, Venkatessh Ramakrishnan, Philippe Raffin, Ignacio Ruiz, Mahito Sasada, Kamal Souccar, Joseph Neilsen, J. G. A. Wouterloot, Jirong Mao, Colin J. Lonsdale, Feng Yuan, Jadyn Anczarski, Lindy Blackburn, N. Phillips, Don Sousa, Ramesh Narayan, Alan R. Whitney, Paul T. P. Ho, Kyle D. Massingill, Patrick M. Koch, Taehyun Jung, Erik M. Leitch, Junhan Kim, Nicolas Pradel, Kevin A. Dudevoir, Britton Jeter, Jason SooHoo, Tomohisa Kawashima, T. M. Crawford, Mark Gurwell, A. Montaña, R. P. Eatough, Sascha Trippe, Ivan Marti-Vidal, Dirk Muders, Craig Walther, Atish Kamble, Qingwen Wu, Chunchong Ni, George Nystrom, Yusuke Kono, Ryan Keisler, Huib Jan van Langevelde, Stefan Heyminck, Kenji Toma, Do-Young Byun, Sjoerd T. Timmer, Antxon Alberdi, Hung Yi Pu, Hugo Messias, Feryal Özel, Kotaro Moriyama, John David, M. Poirier, Mislav Baloković, Fumie Tazaki, Keiichi Asada, S. Sánchez, Wu Jiang, Tomoaki Oyama, Shami Chatterjee, Des Small, Richard Lacasse, Ray Blundell, Motoki Kino, Michael A. Nowak, Jason Dexter, Walter Alef, Jinchi Hao, Zhiyuan Li, Garrett K. Keating, Christian M. Fromm, Cornelia Müller, Ching Tang Liu, Alexandra S. Rahlin, William Montgomerie, Andrei P. Lobanov, Bradford Benson, George N. Wong, Kazuhiro Hada, Sven Dornbusch, George Reiland, Boris Georgiev, Luciano Rezzolla, Jongsoo Kim, W. Boland, Ramprasad Rao, Guang-Yao Zhao, Buell T. Jannuzi, Sandra Bustamente, Daniel C. M. Palumbo, Tod R. Lauer, Karl Friedrich Schuster, Ronald Hesper, Zheng Meyer-Zhao, John Kuroda, Ramesh Karuppusamy, Pierre Martin-Cocher, Chi-kwan Chan, Timothy C. Chuter, Izumi Mizuno, Vincent L. Fish, Yutaka Hasegawa, Roberto Neri, Matthew R. Dexter, Paul Tiede, Rodrigo Amestica, S. Navarro, William T. Freeman, Callie Matulonis, Luis C. Ho, Hideo Ogawa, Shiro Ikeda, Ralph G. Marson, A. Nadolski, J. Blanchard, Ed Fomalont, Monika Moscibrodzka, Nicholas R. MacDonald, Gisela N. Ortiz-León, Bong Won Sohn, David C. Forbes, Lynn D. Matthews, Avery E. Broderick, Ziri Younsi, Tuomas Savolainen, Neil M. Nagar, Alexander Allardi, M. Mora-Klein, Yuzhu Cui, Yan-Rong Li, Koushik Chatterjee, Rebecca Azulay, M. Zeballos, Alan E. E. Rogers, Event Horizon Telescope Collaboration, T., Akiyama, K., Alberdi, A., Alef, W., Asada, K., Azulay, R., Baczko, A. -K., Ball, D., Balokovic, M., Barrett, J., Bintley, D., Blackburn, L., Boland, W., Bouman, K. L., Bower, G. C., Bremer, M., Brinkerink, C. D., Brissenden, R., Britzen, S., Broderick, A. E., Broguiere, D., Bronzwaer, T., Byun, D. -Y., Carlstrom, J. E., Chael, A., Chan, C. -K., Chatterjee, S., Chatterjee, K., Chen, M. -T., Chen, Y., Cho, I., Christian, P., Conway, J. E., Cordes, J. M., Crew, G. B., Cui, Y., Davelaar, J., De Laurentis, M., Deane, R., Dempsey, J., Desvignes, G., Dexter, J., Doeleman, S. S., Eatough, R. P., Falcke, H., Fish, V. L., Fomalont, E., Fraga-Encinas, R., Freeman, W. T., Friberg, P., Fromm, C. M., Gomez, J. L., Galison, P., Gammie, C. F., Garcia, R., Gentaz, O., Georgiev, B., Goddi, C., Gold, R., Gu, M., Gurwell, M., Hada, K., Hecht, M. H., Hesper, R., Ho, L. C., Ho, P., Honma, M., Huang, C. -W. L., Huang, L., Hughes, D. H., Ikeda, S., Inoue, M., Issaoun, S., James, D. J., Jannuzi, B. T., Janssen, M., Jeter, B., Jiang, W., Johnson, M. D., Jorstad, S., Jung, T., Karami, M., Karuppusamy, R., Kawashima, T., Keating, G. K., Kettenis, M., Kim, J. -Y., Kim, J., Kino, M., Koay, J. Y., Koch, P. M., Koyama, S., Kramer, M., Kramer, C., Krichbaum, T. P., Kuo, C. -Y., Lauer, T. R., Lee, S. -S., Li, Y. -R., Li, Z., Lindqvist, M., Liu, K., Liuzzo, E., Lo, W. -P., Lobanov, A. P., Loinard, L., Lonsdale, C., Lu, R. -S., Macdonald, N. R., Mao, J., Markoff, S., Marrone, D. P., Marscher, A. P., Marti-Vidal, I., Matsushita, S., Matthews, L. D., Medeiros, L., Menten, K. M., Mizuno, Y., Mizuno, I., Moran, J. M., Moriyama, K., Moscibrodzka, M., Muller, C., Nagai, H., Nagar, N. M., Nakamura, M., Narayan, R., Narayanan, G., Natarajan, I., Neri, R., Ni, C., Noutsos, A., Okino, H., Olivares, H., Ortiz-Leon, G. N., Oyama, T., Ozel, F., Palumbo, D. C. M., Patel, N., Pen, U. -L., Pesce, D. W., Pietu, V., Plambeck, R., Popstefanija, A., Porth, O., Prather, B., Preciado-Lopez, J. A., Psaltis, D., Pu, H. -Y., Ramakrishnan, V., Rao, R., Rawlings, M. G., Raymond, A. W., Rezzolla, L., Ripperda, B., Roelofs, F., Rogers, A., Ros, E., Rose, M., Roshanineshat, A., Rottmann, H., Roy, A. L., Ruszczyk, C., Ryan, B. R., Rygl, K. L. J., Sanchez, S., Sanchez-Arguelles, D., Sasada, M., Savolainen, T., Schloerb, F. P., Schuster, K. -F., Shao, L., Shen, Z., Small, D., Sohn, B. W., Soohoo, J., Tazaki, F., Tiede, P., Tilanus, R. P. J., Titus, M., Toma, K., Torne, P., Trent, T., Trippe, S., Tsuda, S., Bemmel, I. V., Van Langevelde, H. J., Van Rossum, D. R., Wagner, J., Wardle, J., Weintroub, J., Wex, N., Wharton, R., Wielgus, M., Wong, G. N., Wu, Q., Young, K., Young, A., Younsi, Z., Yuan, F., Yuan, Y. -F., Zensus, J. A., Zhao, G., Zhao, S. -S., Zhu, Z., Algaba, J. -C., Allardi, A., Amestica, R., Anczarski, J., Bach, U., Baganoff, F. K., Beaudoin, C., Benson, B. A., Berthold, R., Blanchard, J. M., Blundell, R., Bustamente, S., Cappallo, R., Castillo-Dominguez, E., Chang, C. -C., Chang, S. -H., Chang, S. -C., Chen, C. -C., Chilson, R., Chuter, T. C., Rosado, R. C., Coulson, I. M., Crawford, T. M., Crowley, J., David, J., Derome, M., Dexter, M., Dornbusch, S., Dudevoir, K. A., Dzib, S. A., Eckart, A., Eckert, C., Erickson, N. R., Everett, W. B., Faber, A., Farah, J. R., Fath, V., Folkers, T. W., Forbes, D. C., Freund, R., Gomez-Ruiz, A. I., Gale, D. M., Gao, F., Geertsema, G., Graham, D. A., Greer, C. H., Grosslein, R., Gueth, F., Haggard, D., Halverson, N. W., Han, C. -C., Han, K. -C., Hao, J., Hasegawa, Y., Henning, J. W., Hernandez-Gomez, A., Herrero-Illana, R., Heyminck, S., Hirota, A., Hoge, J., Huang, Y. -D., Impellizzeri, C. M. V., Jiang, H., Kamble, A., Keisler, R., Kimura, K., Kono, Y., Kubo, D., Kuroda, J., Lacasse, R., Laing, R. A., Leitch, E. M., Li, C. -T., Lin, L. C. -C., Liu, C. -T., Liu, K. -Y., Lu, L. -M., Marson, R. G., Martin-Cocher, P. L., Massingill, K. D., Matulonis, C., Mccoll, M. P., Mcwhirter, S. R., Messias, H., Meyer-Zhao, Z., Michalik, D., Montana, A., Montgomerie, W., Mora-Klein, M., Muders, D., Nadolski, A., Navarro, S., Neilsen, J., Nguyen, C. H., Nishioka, H., Norton, T., Nowak, M. A., Nystrom, G., Ogawa, H., Oshiro, P., Parsons, H., Paine, S. N., Penalver, J., Phillips, N. M., Poirier, M., Pradel, N., Primiani, R. A., Raffin, P. A., Rahlin, A. S., Reiland, G., Risacher, C., Ruiz, I., Saez-Madain, A. F., Sassella, R., Schellart, P., Shaw, P., Silva, K. M., Shiokawa, H., Smith, D. R., Snow, W., Souccar, K., Sousa, D., Sridharan, T. K., Srinivasan, R., Stahm, W., Stark, A. A., Story, K., Timmer, S. T., Vertatschitsch, L., Walther, C., Wei, T. -S., Whitehorn, N., Whitney, A. R., Woody, D. P., Wouterloot, J. G. A., Wright, M., Yamaguchi, P., Yu, C. -Y., Zeballos, M., Zhang, S., Ziurys, L., Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Instituto de RadioAstronomía Milimétrica (IRAM), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Event Horizon Telescope, Academy of Finland, European Commission, Alexander von Humboldt Foundation, John Templeton Foundation, China Scholarship Council, Comisión Nacional de Investigación Científica y Tecnológica (Chile), Consejo Nacional de Ciencia y Tecnología (México), European Research Council, Generalitat Valenciana, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Gordon and Betty Moore Foundation, Istituto Nazionale di Fisica Nucleare, Japanese Government, Japan Society for the Promotion of Science, Chinese Academy of Sciences, Max Planck Society, Ministry of Science and Technology (Taiwan), National Aeronautics and Space Administration (US), National Science Foundation (US), National Natural Science Foundation of China, Natural Sciences and Engineering Research Council of Canada, National Research Foundation of Korea, Netherlands Organization for Scientific Research, National Research Foundation (South Africa), Russian Science Foundation, Ministero dell'Istruzione, dell'Università e della Ricerca, Alberdi, Antxón, Gómez Fernández, J. L., Alberdi, Antxón [0000-0002-9371-1033], Gómez Fernández, J. L. [0000-0003-4190-7613], Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Anne Lähteenmäki Group, Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Astronomy, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Gravitation and Astroparticle Physics Amsterdam

Subjects
010504 meteorology & atmospheric sciences, individual (M87) [galaxies], Event horizon, Astronomy, black hole physics, jets [galaxies], galaxies: individual, Astrophysics, high-resolution, 7. Clean energy, 01 natural sciences, Photon sphere, General Relativity and Quantum Cosmology, accretion, sagittarius-a-asterisk, 010303 astronomy & astrophysics, galactic-center, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, radio-sources, accretion disks, Galactic Center, grmhd simulations, 3. Good health, energy-distributions, active [galaxies], Anatomy, Astrophysics - High Energy Astrophysical Phenomena, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, galaxies: individual: M87, galaxies: individual (M87), Cell and Developmental Biology, 0103 physical sciences, (M87), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Event Horizon Telescope, Supermassive black hole, ghz vlbi observations, faraday-rotation, Astronomy and Astrophysics, galaxies: jets, Astrophysics - Astrophysics of Galaxies, Black hole, Rotating black hole, Space and Planetary Science, gravitation, Astrophysics of Galaxies (astro-ph.GA), advection-dominated accretion, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ionized-gas
Abstract

When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux ratio 10:1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 ± 0.7) × 109 Me. Our radiowave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.© 2019. The American Astronomical Society, The authors of this Letter thank the following organizations and programs: the Academy of Finland (projects 274477, 284495, 312496); the Advanced European Network of E-infrastructures for Astronomy with the SKA (AENEAS) project, supported by the European Commission Framework Programme Horizon 2020 Research and Innovation action under grant agreement 731016; the Alexander von Humboldt Stiftung; the Black Hole Initiative at Harvard University, through a grant (60477) from the John Templeton Foundation; the China Scholarship Council; Comisión Nacional de Investigación Científica y Tecnológica (CONICYT, Chile, via PIA ACT172033, Fondecyt 1171506, BASAL AFB170002, ALMA-conicyt 31140007); Consejo Nacional de Ciencia y Tecnología (CONACYT, Mexico, projects 104497, 275201, 279006, 281692); the Delaney Family via the Delaney Family John A. Wheeler Chair at Perimeter Institute; Dirección General de Asuntos del Personal Académico-Universidad Nacional 9 The Astrophysical Journal Letters, 875:L1 (17pp), 2019 April 10 The EHT Collaboration et al. Autónoma de México (DGAPA-UNAM, project IN112417); the European Research Council (ERC) Synergy Grant “BlackHoleCam: Imaging the Event Horizon of Black Holes” (grant 610058); the Generalitat Valenciana postdoctoral grant APOSTD/2018/177; the Gordon and Betty Moore Foundation (grants GBMF-3561, GBMF-5278); the Istituto Nazionale di Fisica Nucleare (INFN) sezione di Napoli, iniziative specifiche TEONGRAV; the International Max Planck Research School for Astronomy and Astrophysics at the Universities of Bonn and Cologne; the Jansky Fellowship program of the National Radio Astronomy Observatory (NRAO); the Japanese Government (Monbukagakusho: MEXT) Scholarship; the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for JSPS Research Fellowship (JP17J08829); JSPS Overseas Research Fellowships; the Key Research Program of Frontier Sciences, Chinese, Academy of Sciences (CAS, grants QYZDJ-SSW-SLH057, QYZDJ-SSW-SYS008); the Leverhulme Trust Early Career Research Fellowship; the Max-Planck-Gesellschaft (MPG); the Max Planck Partner Group of the MPG and the CAS; the MEXT/JSPS KAKENHI (grants 18KK0090, JP18K13594, JP18K03656, JP18H03721, 18K03709, 18H01245, 25120007); the MIT International Science and Technology Initiatives (MISTI) Funds; the Ministry of Science and Technology (MOST) of Taiwan (105-2112-M-001-025-MY3, 106-2112-M001-011, 106-2119-M-001-027, 107-2119-M-001-017, 107- 2119-M-001-020, and 107-2119-M-110-005); the National Aeronautics and Space Administration (NASA, Fermi Guest Investigator grant 80NSSC17K0649); the National Institute of Natural Sciences (NINS) of Japan; the National Key Research and Development Program of China (grant 2016YFA0400704, 2016YFA0400702); the National Science Foundation (NSF, grants AST-0096454, AST-0352953, AST-0521233, AST0705062, AST-0905844, AST-0922984, AST-1126433, AST1140030, DGE-1144085, AST-1207704, AST-1207730, AST1207752, MRI-1228509, OPP-1248097, AST-1310896, AST1312651, AST-1337663, AST-1440254, AST-1555365, AST1715061, AST-1615796, AST-1614868, AST-1716327, OISE1743747, AST-1816420); the Natural Science Foundation of China (grants 11573051, 11633006, 11650110427, 10625314, 11721303, 11725312, 11873028, 11873073, U1531245, 11473010); the Natural Sciences and Engineering Research Council of Canada (NSERC, including a Discovery Grant and the NSERC Alexander Graham Bell Canada Graduate Scholarships-Doctoral Program); the National Youth Thousand Talents Program of China; the National Research Foundation of Korea (grant 2015-R1D1A1A01056807, the Global PhD Fellowship Grant: NRF-2015H1A2A1033752, and the Korea Research Fellowship Program: NRF-2015H1D3A1066561); the Netherlands Organization for Scientific Research (NWO) VICI award (grant 639.043.513) and Spinoza Prize (SPI 78-409); the New Scientific Frontiers with Precision, Radio Interferometry Fellowship awarded by the South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation (NRF), an agency of the Department of Science and Technology (DST) of South Africa; the Onsala Space Observatory (OSO) national infrastructure, for the provisioning of its facilities/observational support (OSO receives funding through the Swedish Research Council under grant 2017-00648); the Perimeter Institute for Theoretical Physics (research at Perimeter Institute is supported by the Government of Canada through the Department of Innovation, Science and Economic Development Canada and by the Province of Ontario through the Ministry of Economic Development, Job Creation and Trade); the Russian Science Foundation (grant 17-12-01029); the Spanish Ministerio de Economía y Competitividad (grants AYA2015-63939-C2-1-P, AYA2016-80889-P); the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709); the Toray Science Foundation; the US Department of Energy (USDOE) through the Los Alamos National Laboratory (operated by Triad National Security, LLC, for the National Nuclear Security Administration of the USDOE (Contract 89233218CNA000001)); the Italian Ministero dell’Istruzione Università e Ricerca through the grant Progetti Premiali 2012-iALMA (CUP C52I13000140001); the European Unionʼs Horizon 2020 research and innovation programme under grant agreement No 730562 RadioNet; ALMA North America Development Fund; Chandra TM6-17006X

Published
2019

29. First M87 Event Horizon Telescope Results. II. Array and Instrumentation

Author

Monika Moscibrodzka, Elisabetta Liuzzo, F. Peter Schloerb, John Conway, Remi Sassella, Eduardo Ros, Kevin M. Silva, Christopher Beaudoin, Minfeng Gu, Stephen R. McWhirter, Nicholas R. MacDonald, Derek Kubo, E. Castillo-Domínguez, Iain Coulson, Katherine L. Bouman, John E. Barrett, Peter Oshiro, Peter Galison, Walter Alef, Ignacio Ruiz, N. Phillips, Gisela N. Ortiz-León, Ye-Fei Yuan, Arturo I. Gómez-Ruiz, Scott Paine, Dimitrios Psaltis, Mareki Honma, Juan-Carlos Algaba, Daniel P. Marrone, Alexandra S. Rahlin, Li Ming Lu, Iniyan Natarajan, Thomas W. Folkers, Zhiqiang Shen, Mariafelicia De Laurentis, Kuo Liu, Chao-Te Li, M. C. H. Wright, Mansour Karami, José L. Gómez, Roger J. Cappallo, Roger Deane, Lucy M. Ziurys, Yi Chen, Christopher Greer, William Montgomerie, Andrei P. Lobanov, George N. Wong, Bong Won Sohn, Huib Jan van Langevelde, Mark Gurwell, Ivan Marti-Vidal, Ilje Cho, Hotaka Shiokawa, Martin P. McColl, Makoto Inoue, Shu Hao Chang, K. T. Story, Joseph Crowley, C. M.Violette Impellizzeri, Kazuhiro Hada, Michael Kramer, Ranjani Srinivasan, David Ball, Keiichi Asada, Des Small, Hung Yi Pu, John David, Tomoaki Oyama, Svetlana G. Jorstad, Boris Georgiev, Sheperd S. Doeleman, Oliver Porth, Nathan Whitehorn, Alan L. Roy, Kazunori Akiyama, W. B. Everett, Maciek Wielgus, Don Sousa, J. Blanchard, Ray Blundell, Motoki Kino, Karl Friedrich Schuster, Ronald Hesper, Zheng Meyer-Zhao, John Kuroda, Heino Falcke, Chung Chen Chen, Carsten Kramer, Thomas P. Krichbaum, R. P. Eatough, S. Sánchez, Roberto Garcia, Jan Wagner, Ramesh Karuppusamy, Raquel Fraga-Encinas, Hiroaki Nishioka, Mark G. Rawlings, Ed Fomalont, W. Boland, Ramprasad Rao, Timothy Norton, Ching Tang Liu, James M. Cordes, Bradford Benson, Dominic W. Pesce, Yan-Rong Li, Geoffrey B. Crew, Vernon Fath, Frederic Gueth, David Sánchez-Arguelles, Roger Brissenden, Chi-kwan Chan, Timothy C. Chuter, Qingwen Wu, Chunchong Ni, Yuzhu Cui, Guang-Yao Zhao, Harriet Parsons, Ken H. Young, Paul Yamaguchi, Mahito Sasada, Daniel R. van Rossum, Yusuke Kono, Ryan Keisler, Masanori Nakamura, Patrick M. Koch, Nicolas Pradel, Ramesh Narayan, Rodrigo Córdova Rosado, Jordy Davelaar, Hiroshi Nagai, Chih Cheng Chang, Joseph R. Farah, Ben Prather, Laura Vertatschitsch, Britton Jeter, Kuo Chang Han, Shoko Koyama, William Snow, Lindy Blackburn, Erik M. Leitch, Rurik A. Primiani, Pierre Christian, Kyle D. Massingill, Shiro Ikeda, Remo P. J. Tilanus, S. A. Dzib, Charles F. Gammie, Ziyan Zhu, Ralph G. Marson, Aleksandar Popstefanija, Helge Rottmann, Chris Eckert, Lupin C.C. Lin, Michael H. Hecht, Silke Britzen, J. Anton Zensus, Christian M. Fromm, Sera Markoff, Wu Jiang, Cornelia Müller, A. Nadolski, David H. Hughes, Zhiyuan Li, Ue-Li Pen, Yosuke Mizuno, Sascha Trippe, Jinchi Hao, Gertie Geertsema, Garrett K. Keating, Lei Huang, Chi H. Nguyen, Koushik Chatterjee, Andrew Chael, Norbert Wex, Ronald Grosslein, Nimesh A. Patel, Aaron Faber, Rebecca Azulay, Stefan Heyminck, Kenji Toma, Do-Young Byun, Christopher Risacher, Wen Ping Lo, Geoffrey C. Bower, James M. Moran, Tyler Trent, Satoki Matsushita, Bart Ripperda, Dominique Broguiere, Antxon Alberdi, Kazi L.J. Rygl, Chet Ruszczyk, T. K. Sridharan, Antony A. Stark, Michael Bremer, James Hoge, M. Zeballos, Kamal Souccar, Paul T. P. Ho, Atish Kamble, Ciriaco Goddi, Feng Gao, Yau De Huang, Dan Bintley, Alan E. E. Rogers, Ryan Chilson, Jorge A. Preciado-López, A. Montaña, Hector Olivares, Mark Derome, Michael Janssen, Robert Freund, Thomas Bronzwaer, Jun Yi Koay, Kevin A. Dudevoir, Roberto Neri, Buell T. Jannuzi, Sandra Bustamente, Mislav Baloković, S. Navarro, Shami Chatterjee, Tod R. Lauer, Alejandro F. Sáez-Madain, Sjoerd T. Timmer, Chih Chiang Han, John E. Carlstrom, Luis C. Ho, Hugo Messias, Feryal Özel, Shuichiro Tsuda, Ryan Berthold, Taehyun Jung, Akihiko Hirota, Richard Lacasse, D. A. Graham, Vincent Piétu, Homin Jiang, Shan Shan Zhao, Lia Medeiros, Song Chu Chang, Jae-Young Kim, Hideo Ogawa, Sara Issaoun, Kotaro Moriyama, Stephen Padin, Roman Gold, N. W. Halverson, Venkatessh Ramakrishnan, C. Y. Kuo, Benjamin R. Ryan, Jason Dexter, Paul Shaw, Alan R. Whitney, Karl M. Menten, Aristeidis Noutsos, Kimihiro Kimura, Mark Kettenis, Ming-Tang Chen, Jonathan Weintroub, Neal R. Erickson, Chen Yu Yu, David R. Smith, André Young, Luciano Rezzolla, Jongsoo Kim, M. Poirier, Robert Wharton, Daniel C. M. Palumbo, Pierre Martin-Cocher, Hiroki Okino, Yutaka Hasegawa, Kuan Yu Liu, David P. Woody, Sven Dornbusch, George Reiland, Arash Roshanineshat, Pablo Torne, Daniel Michalik, John Wardle, David M. Gale, Ta Shun Wei, Uwe Bach, Ilse van Bemmel, Izumi Mizuno, Vincent L. Fish, Antonio Hernández-Gómez, Matthew R. Dexter, Paul Tiede, Rodrigo Amestica, Pim Schellart, Michael D. Johnson, Mel Rose, Callie Matulonis, J. G. A. Wouterloot, Jason SooHoo, Tomohisa Kawashima, T. M. Crawford, Dirk Muders, Craig Walther, Richard L. Plambeck, William Stahm, George Nystrom, David C. Forbes, Lynn D. Matthews, Avery E. Broderick, Ziri Younsi, Tuomas Savolainen, Neil M. Nagar, Alexander Allardi, M. Mora-Klein, Fumie Tazaki, Michael Lindqvist, Per Friberg, Olivier Gentaz, David J. James, Alan P. Marscher, Sang-Sung Lee, Chih-Wei Locutus Huang, Lijing Shao, Christiaan D. Brinkerink, Jason W. Henning, R. Laing, Feng Yuan, Junhan Kim, J. Peñalver, Michael Titus, Freek Roelofs, Laurent Loinard, Rubén Herrero-Illana, Gopal Narayanan, Alexander W. Raymond, Gregory Desvignes, Anne Kathrin Baczko, Ru-Sen Lu, Philippe Raffin, Jirong Mao, Colin J. Lonsdale, Jessica Dempsey, Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Instituto de RadioAstronomía Milimétrica (IRAM), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Event Horizon Telescope, Astronomy, Anne Lähteenmäki Group, Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Academy of Finland, European Commission, Alexander von Humboldt Foundation, John Templeton Foundation, China Scholarship Council, Comisión Nacional de Investigación Científica y Tecnológica (Chile), Consejo Nacional de Ciencia y Tecnología (México), European Research Council, Generalitat Valenciana, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Gordon and Betty Moore Foundation, Istituto Nazionale di Fisica Nucleare, Japanese Government, Japan Society for the Promotion of Science, Chinese Academy of Sciences, Max Planck Society, Ministry of Science and Technology (Taiwan), National Aeronautics and Space Administration (US), National Science Foundation (US), National Natural Science Foundation of China, Natural Sciences and Engineering Research Council of Canada, National Research Foundation of Korea, Netherlands Organization for Scientific Research, National Research Foundation (South Africa), Russian Science Foundation, Ministero dell'Istruzione, dell'Università e della Ricerca, Alberdi, Antxón [0000-0002-9371-1033], Gómez Fernández, J. L. [0000-0003-4190-7613], Event Horizon Telescope Collaboration, T., Akiyama, K., Alberdi, A., Alef, W., Asada, K., Azulay, R., Baczko, A. -K., Ball, D., Balokovic, M., Barrett, J., Bintley, D., Blackburn, L., Boland, W., Bouman, K. L., Bower, G. C., Bremer, M., Brinkerink, C. D., Brissenden, R., Britzen, S., Broderick, A. E., Broguiere, D., Bronzwaer, T., Byun, D. -Y., Carlstrom, J. E., Chael, A., Chan, C. -K., Chatterjee, S., Chatterjee, K., Chen, M. -T., Chen, Y., Cho, I., Christian, P., Conway, J. E., Cordes, J. M., Crew, G. B., Cui, Y., Davelaar, J., De Laurentis, M., Deane, R., Dempsey, J., Desvignes, G., Dexter, J., Doeleman, S. S., Eatough, R. P., Falcke, H., Fish, V. L., Fomalont, E., Fraga-Encinas, R., Friberg, P., Fromm, C. M., Gomez, J. L., Galison, P., Gammie, C. F., Garcia, R., Gentaz, O., Georgiev, B., Goddi, C., Gold, R., Gu, M., Gurwell, M., Hada, K., Hecht, M. H., Hesper, R., Ho, L. C., Ho, P., Honma, M., Huang, C. -W. L., Huang, L., Hughes, D. H., Ikeda, S., Inoue, M., Issaoun, S., James, D. J., Jannuzi, B. T., Janssen, M., Jeter, B., Jiang, W., Johnson, M. D., Jorstad, S., Jung, T., Karami, M., Karuppusamy, R., Kawashima, T., Keating, G. K., Kettenis, M., Kim, J. -Y., Kim, J., Kino, M., Koay, J. Y., Koch, P. M., Koyama, S., Kramer, M., Kramer, C., Krichbaum, T. P., Kuo, C. -Y., Lauer, T. R., Lee, S. -S., Li, Y. -R., Li, Z., Lindqvist, M., Liu, K., Liuzzo, E., Lo, W. -P., Lobanov, A. P., Loinard, L., Lonsdale, C., Lu, R. -S., Macdonald, N. R., Mao, J., Markoff, S., Marrone, D. P., Marscher, A. P., Marti-Vidal, I., Matsushita, S., Matthews, L. D., Medeiros, L., Menten, K. M., Mizuno, Y., Mizuno, I., Moran, J. M., Moriyama, K., Moscibrodzka, M., Muller, C., Nagai, H., Nagar, N. M., Nakamura, M., Narayan, R., Narayanan, G., Natarajan, I., Neri, R., Ni, C., Noutsos, A., Okino, H., Olivares, H., Ortiz-Leon, G. N., Oyama, T., Ozel, F., Palumbo, D. C. M., Patel, N., Pen, U. -L., Pesce, D. W., Pietu, V., Plambeck, R., Popstefanija, A., Porth, O., Prather, B., Preciado-Lopez, J. A., Psaltis, D., Pu, H. -Y., Ramakrishnan, V., Rao, R., Rawlings, M. G., Raymond, A. W., Rezzolla, L., Ripperda, B., Roelofs, F., Rogers, A., Ros, E., Rose, M., Roshanineshat, A., Rottmann, H., Roy, A. L., Ruszczyk, C., Ryan, B. R., Rygl, K. L. J., Sanchez, S., Sanchez-Arguelles, D., Sasada, M., Savolainen, T., Schloerb, F. P., Schuster, K. -F., Shao, L., Shen, Z., Small, D., Sohn, B. W., Soohoo, J., Tazaki, F., Tiede, P., Tilanus, R. P. J., Titus, M., Toma, K., Torne, P., Trent, T., Trippe, S., Tsuda, S., Van Bemmel, I., Van Langevelde, H. J., Van Rossum, D. R., Wagner, J., Wardle, J., Weintroub, J., Wex, N., Wharton, R., Wielgus, M., Wong, G. N., Wu, Q., Young, A., Young, K., Younsi, Z., Yuan, F., Yuan, Y. -F., Zensus, J. A., Zhao, G., Zhao, S. -S., Zhu, Z., Algaba, J. -C., Allardi, A., Amestica, R., Bach, U., Beaudoin, C., Benson, B. A., Berthold, R., Blanchard, J. M., Blundell, R., Bustamente, S., Cappallo, R., Castillo-Dominguez, E., Chang, C. -C., Chang, S. -H., Chang, S. -C., Chen, C. -C., Chilson, R., Chuter, T. C., Rosado, R. C., Coulson, I. M., Crawford, T. M., Crowley, J., David, J., Derome, M., Dexter, M., Dornbusch, S., Dudevoir, K. A., Dzib, S. A., Eckert, C., Erickson, N. R., Everett, W. B., Faber, A., Farah, J. R., Fath, V., Folkers, T. W., Forbes, D. C., Freund, R., Gomez-Ruiz, A. I., Gale, D. M., Gao, F., Geertsema, G., Graham, D. A., Greer, C. H., Grosslein, R., Gueth, F., Halverson, N. W., Han, C. -C., Han, K. -C., Hao, J., Hasegawa, Y., Henning, J. W., Hernandez-Gomez, A., Herrero-Illana, R., Heyminck, S., Hirota, A., Hoge, J., Huang, Y. -D., Impellizzeri, C. M. V., Jiang, H., Kamble, A., Keisler, R., Kimura, K., Kono, Y., Kubo, D., Kuroda, J., Lacasse, R., Laing, R. A., Leitch, E. M., Li, C. -T., Lin, L. C. -C., Liu, C. -T., Liu, K. -Y., Lu, L. -M., Marson, R. G., Martin-Cocher, P. L., Massingill, K. D., Matulonis, C., Mccoll, M. P., Mcwhirter, S. R., Messias, H., Meyer-Zhao, Z., Michalik, D., Montana, A., Montgomerie, W., Mora-Klein, M., Muders, D., Nadolski, A., Navarro, S., Nguyen, C. H., Nishioka, H., Norton, T., Nystrom, G., Ogawa, H., Oshiro, P., Padin, S., Parsons, H., Paine, S. N., Penalver, J., Phillips, N. M., Poirier, M., Pradel, N., Primiani, R. A., Raffin, P. A., Rahlin, A. S., Reiland, G., Risacher, C., Ruiz, I., Saez-Madain, A. F., Sassella, R., Schellart, P., Shaw, P., Silva, K. M., Shiokawa, H., Smith, D. R., Snow, W., Souccar, K., Sousa, D., Sridharan, T. K., Srinivasan, R., Stahm, W., Stark, A. A., Story, K., Timmer, S. T., Vertatschitsch, L., Walther, C., Wei, T. -S., Whitehorn, N., Whitney, A. R., Woody, D. P., Wouterloot, J. G. A., Wright, M., Yamaguchi, P., Yu, C. -Y., Zeballos, M., Ziurys, L., Alberdi, Antxón, Gómez Fernández, J. L., High Energy Astrophys. & Astropart. Phys (API, FNWI), and Gravitation and Astroparticle Physics Amsterdam

Subjects
010504 meteorology & atmospheric sciences, individual (M87) [galaxies], Event horizon, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, interferometers [instrumentation], black hole physics, FOS: Physical sciences, galaxies: individual, General Relativity and Quantum Cosmology (gr-qc), galaxies: individual: M87, 01 natural sciences, General Relativity and Quantum Cosmology, galaxies: individual (M87), instrumentation: interferometer, 0103 physical sciences, Very-long-baseline interferometry, Angular resolution, Instrumentation (computer programming), instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, high angular resolution [echniques], Event Horizon Telescope, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, Galaxy: center, high angular resolution [techniques], techniques: high angular resolution, gravitational lensing: strong, Astronomy and Astrophysics, center [Galaxy], Hydrogen maser, black hole physic, Astrophysics - Astrophysics of Galaxies, echniques: high angular resolution, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), strong [gravitational lensing], Millimeter, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of ~1.3 mm, EHT angular resolution (λ/D) is ~25 μas, which is sufficient to resolve nearby supermassive black hole candidates on spatial and temporal scales that correspond to their event horizons. With this capability, the EHT scientific goals are to probe general relativistic effects in the strong-field regime and to study accretion and relativistic jet formation near the black hole boundary. In this Letter we describe the system design of the EHT, detail the technology and instrumentation that enable observations, and provide measures of its performance. Meeting the EHT science objectives has required several key developments that have facilitated the robust extension of the VLBI technique to EHT observing wavelengths and the production of instrumentation that can be deployed on a heterogeneous array of existing telescopes and facilities. To meet sensitivity requirements, high-bandwidth digital systems were developed that process data at rates of 64 gigabit s−1, exceeding those of currently operating cm-wavelength VLBI arrays by more than an order of magnitude. Associated improvements include the development of phasing systems at array facilities, new receiver installation at several sites, and the deployment of hydrogen maser frequency standards to ensure coherent data capture across the array. These efforts led to the coordination and execution of the first Global EHT observations in 2017 April, and to event-horizon-scale imaging of the supermassive black hole candidate in M87.© 2019. The American Astronomical Society, The authors of this Letter thank the following organizations and programs: the Academy of Finland (projects 274477, 284495, 312496); the Advanced European Network of E-infrastructures for Astronomy with the SKA (AENEAS) project, supported by the European Commission Framework Programme Horizon 2020 Research and Innovation action under grant agreement 731016; the Alexander von Humboldt Stiftung; the Black Hole Initiative at Harvard University, through a grant (60477) from the John Templeton Foundation; the China Scholarship Council; Comisión Nacional de Investigación Científica y Tecnológica (CONICYT, Chile, via PIA ACT172033, Fondecyt 1171506, BASAL AFB170002, ALMA-conicyt 31140007); Consejo Nacional de Ciencia y Tecnología (CONACYT, Mexico, projects 104497, 275201, 279006, 281692); the Delaney Family via the Delaney Family John A. Wheeler Chair at Perimeter Institute; Dirección General de Asuntos del Personal Académico-Universidad Nacional 9 The Astrophysical Journal Letters, 875:L1 (17pp), 2019 April 10 The EHT Collaboration et al. Autónoma de México (DGAPA-UNAM, project IN112417); the European Research Council (ERC) Synergy Grant “BlackHoleCam: Imaging the Event Horizon of Black Holes” (grant 610058); the Generalitat Valenciana postdoctoral grant APOSTD/2018/177; the Gordon and Betty Moore Foundation (grants GBMF-3561, GBMF-5278); the Istituto Nazionale di Fisica Nucleare (INFN) sezione di Napoli, iniziative specifiche TEONGRAV; the International Max Planck Research School for Astronomy and Astrophysics at the Universities of Bonn and Cologne; the Jansky Fellowship program of the National Radio Astronomy Observatory (NRAO); the Japanese Government (Monbukagakusho: MEXT) Scholarship; the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for JSPS Research Fellowship (JP17J08829); JSPS Overseas Research Fellowships; the Key Research Program of Frontier Sciences, Chinese, Academy of Sciences (CAS, grants QYZDJ-SSW-SLH057, QYZDJ-SSW-SYS008); the Leverhulme Trust Early Career Research Fellowship; the Max-Planck-Gesellschaft (MPG); the Max Planck Partner Group of the MPG and the CAS; the MEXT/JSPS KAKENHI (grants 18KK0090, JP18K13594, JP18K03656, JP18H03721, 18K03709, 18H01245, 25120007); the MIT International Science and Technology Initiatives (MISTI) Funds; the Ministry of Science and Technology (MOST) of Taiwan (105-2112-M-001-025-MY3, 106-2112-M001-011, 106-2119-M-001-027, 107-2119-M-001-017, 107- 2119-M-001-020, and 107-2119-M-110-005); the National Aeronautics and Space Administration (NASA, Fermi Guest Investigator grant 80NSSC17K0649); the National Institute of Natural Sciences (NINS) of Japan; the National Key Research and Development Program of China (grant 2016YFA0400704, 2016YFA0400702); the National Science Foundation (NSF, grants AST-0096454, AST-0352953, AST-0521233, AST0705062, AST-0905844, AST-0922984, AST-1126433, AST1140030, DGE-1144085, AST-1207704, AST-1207730, AST1207752, MRI-1228509, OPP-1248097, AST-1310896, AST1312651, AST-1337663, AST-1440254, AST-1555365, AST1715061, AST-1615796, AST-1614868, AST-1716327, OISE1743747, AST-1816420); the Natural Science Foundation of China (grants 11573051, 11633006, 11650110427, 10625314, 11721303, 11725312, 11873028, 11873073, U1531245, 11473010); the Natural Sciences and Engineering Research Council of Canada (NSERC, including a Discovery Grant and the NSERC Alexander Graham Bell Canada Graduate Scholarships-Doctoral Program); the National Youth Thousand Talents Program of China; the National Research Foundation of Korea (grant 2015-R1D1A1A01056807, the Global PhD Fellowship Grant: NRF-2015H1A2A1033752, and the Korea Research Fellowship Program: NRF-2015H1D3A1066561); the Netherlands Organization for Scientific Research (NWO) VICI award (grant 639.043.513) and Spinoza Prize (SPI 78-409); the New Scientific Frontiers with Precision, Radio Interferometry Fellowship awarded by the South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation (NRF), an agency of the Department of Science and Technology (DST) of South Africa; the Onsala Space Observatory (OSO) national infrastructure, for the provisioning of its facilities/observational support (OSO receives funding through the Swedish Research Council under grant 2017-00648); the Perimeter Institute for Theoretical Physics (research at Perimeter Institute is supported by the Government of Canada through the Department of Innovation, Science and Economic Development Canada and by the Province of Ontario through the Ministry of Economic Development, Job Creation and Trade); the Russian Science Foundation (grant 17-12-01029); the Spanish Ministerio de Economía y Competitividad (grants AYA2015-63939-C2-1-P, AYA2016-80889-P); the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709); the Toray Science Foundation; the US Department of Energy (USDOE) through the Los Alamos National Laboratory (operated by Triad National Security, LLC, for the National Nuclear Security Administration of the USDOE (Contract 89233218CNA000001)); the Italian Ministero dell’Istruzione Università e Ricerca through the grant Progetti Premiali 2012-iALMA (CUP C52I13000140001); the European Unionʼs Horizon 2020 research and innovation programme under grant agreement No 730562 RadioNet; ALMA North America Development Fund; Chandra TM6-17006X

Published
2019

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