17 research outputs found

    Overlap functions in correlation methods and quasifree nucleon knockout from 16^{16}O

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    The cross sections of the (e,eNe,e'N) and (γ,p\gamma,p) reactions on 16^{16}O are calculated, for the transitions to the 1/21/2^{-} ground state and the first 3/23/2^{-} excited state of the residual nucleus, using single-particle overlap functions obtained on the basis of one-body density matrices within different correlation methods. The electron-induced one-nucleon knockout reaction is treated within a nonrelativistic DWIA framework. The theoretical treatment of the (γ,p\gamma,p) reaction includes both contributions of the direct knockout mechanism and of meson-exchange currents. The results are sensitive to details of the different overlap functions. The consistent analysis of the reaction cross sections and the comparison with the experimental data make it possible to study the nucleon--nucleon correlation effects.Comment: 26 pages, LaTeX, 5 Postscript figures, submitted to PR

    Meson exchange currents in electromagnetic one-nucleon emission

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    The role of meson exchange currents (MEC) in electron- and photon-induced one-nucleon emission processes is studied in a nonrelativistic model including correlations and final state interactions. The nuclear current is the sum of a one-body and of a two-body part. The two-body current includes pion seagull, pion-in-flight and the isobar current contributions. Numerical results are presented for the exclusive 16O(e,e'p)15N and 16O(\gamma,p)15N reactions. MEC effects are in general rather small in (e,e'p), while in (\gamma,p) they are always large and important to obtain a consistent description of (e,e'p) and (\gamma,p) data, with the same spectroscopic factors. The calculated (\gamma,p) cross sections are sensitive to short-range correlations at high values of the recoil momentum, where MEC effects are larger and overwhelm the contribution of correlations.Comment: 9 pages, 6 figure

    All-sky search for long-duration gravitational wave transients with initial LIGO

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    We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

    All-sky search for long-duration gravitational wave transients with initial LIGO

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    We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

    Gravitational waves from known pulsars

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    Item does not contain fulltextIn this paper we have used calibrated data from the Virgo second (Aasi et al. 2012CQGra..29o5002A) and fourth science runs (VSR2 and VSR4) and the LIGO sixth science run (S6). Virgo's third science run (VSR3) was relatively insensitive in comparison with VSR4 and has not been included in this analysis. This was partially because Virgo introduced monolithic mirror suspensions prior to VSR4 which improved sensitivity in the low-frequency range. During S6, the two LIGO 4 km detectors at Hanford, Washington (LHO/H1), and Livingston, Louisiana (LLO/L1), were running in an enhanced configuration (Adhikari et al. 2006, Enhanced LIGO, Tech. Rep. LIGO-T060156-v01, California Institute of Technology, Massachusetts Institute of Technology, https://dcc.ligo.org/LIGO-T060156-v1/public) over that from the previous S5 run (Abbott et al. 2009RPPh...72g6901A)

    Advanced Virgo: a second-generation interferometric gravitational wave detector

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    Contains fulltext : 139575.pdf (preprint version ) (Open Access

    The Advanced Virgo detector

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    Contains fulltext : 143870.pdf (publisher's version ) (Open Access
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