Research Article| November 15, 2017 Low‐Frequency Tilt Seismology with a Precision Ground‐Rotation Sensor M. P. Ross; M. P. Ross aCenter for Experimental Nuclear Physics and Astrophysics (CENPA), University of Washington, 4311 Mason Pl NE, Seattle, Washington 98105 U.S.A., mpross2@uw.edu Search for other works by this author on: GSW Google Scholar K. Venkateswara; K. Venkateswara aCenter for Experimental Nuclear Physics and Astrophysics (CENPA), University of Washington, 4311 Mason Pl NE, Seattle, Washington 98105 U.S.A., mpross2@uw.edu Search for other works by this author on: GSW Google Scholar C. A. Hagedorn; C. A. Hagedorn aCenter for Experimental Nuclear Physics and Astrophysics (CENPA), University of Washington, 4311 Mason Pl NE, Seattle, Washington 98105 U.S.A., mpross2@uw.edu Search for other works by this author on: GSW Google Scholar J. H. Gundlach; J. H. Gundlach aCenter for Experimental Nuclear Physics and Astrophysics (CENPA), University of Washington, 4311 Mason Pl NE, Seattle, Washington 98105 U.S.A., mpross2@uw.edu Search for other works by this author on: GSW Google Scholar J. S. Kissel; J. S. Kissel bLIGO Hanford Observatory, 127124 N Rt. 10, Richland, Washington 99352‐0159 U.S.A. Search for other works by this author on: GSW Google Scholar J. Warner; J. Warner bLIGO Hanford Observatory, 127124 N Rt. 10, Richland, Washington 99352‐0159 U.S.A. Search for other works by this author on: GSW Google Scholar H. Radkins; H. Radkins bLIGO Hanford Observatory, 127124 N Rt. 10, Richland, Washington 99352‐0159 U.S.A. Search for other works by this author on: GSW Google Scholar T. J. Shaffer; T. J. Shaffer bLIGO Hanford Observatory, 127124 N Rt. 10, Richland, Washington 99352‐0159 U.S.A. Search for other works by this author on: GSW Google Scholar M. W. Coughlin; M. W. Coughlin cLIGO Laboratory, California Institute of Technology, MC 100‐36, Pasadena, California 91125 U.S.A. Search for other works by this author on: GSW Google Scholar P. Bodin P. Bodin dDepartment of Earth and Space Sciences, University of Washington, 4000 15th Avenue NE, Seattle, Washington 98195‐1310 U.S.A. Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2018) 89 (1): 67–76. https://doi.org/10.1785/0220170148 Article history first online: 15 Nov 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation M. P. Ross, K. Venkateswara, C. A. Hagedorn, J. H. Gundlach, J. S. Kissel, J. Warner, H. Radkins, T. J. Shaffer, M. W. Coughlin, P. Bodin; Low‐Frequency Tilt Seismology with a Precision Ground‐Rotation Sensor. Seismological Research Letters 2017;; 89 (1): 67–76. doi: https://doi.org/10.1785/0220170148 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search ABSTRACT We describe measurements of the rotational component of teleseismic surface waves using an inertial high‐precision ground‐rotation sensor installed at the Laser Interferometer Gravitational‐Wave Observatory (LIGO) Hanford Observatory (LHO). The sensor has a noise floor of 0.4 nrad/Hz at 50 mHz and a translational coupling of less than 1 μrad/m enabling translation‐free measurement of small rotations. We present observations of the rotational motion from Rayleigh waves of six teleseismic events from varied locations and with magnitudes ranging from M 6.7 to 7.9. These events were used to estimate phase dispersion curves that show agreement with a similar analysis done with an array of three STS‐2 seismometers also located at LHO. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
We present the first Bayesian inference of neutron star crust properties to incorporate neutron skin data, including the recent PREX measurement of the neutron skin of $^{208}$Pb, combined with recent chiral effective field theory predictions of pure neutron matter with statistical errors. Using a compressible liquid drop model with an extended Skyrme energy-density functional, we obtain the most stringent constraints to date on the transition pressure $P_{\rm cc}=0.33^{+0.07}_{-0.07}$ MeV fm$^{-3}$ and chemical potential $\mu_{\rm cc}=12.6^{+1.8}_{-1.9}$ MeV (which control the mass, moment of inertia and thickness of a neutron star crust), the proton fractions that bracket the pasta phases $y_{\rm p}=0.115^{+0.016}_{-0.017}$ and $y_{\rm cc}=0.041^{+0.007}_{-0.006}$, as well as the relative mass and moment of inertia $\Delta M_{\rm p} / \Delta M_{\rm c}\approx \Delta I_{\rm p} / \Delta I_{\rm c} = 0.54^{+0.05}_{-0.09}$ and thickness $\Delta R_{\rm p} / \Delta R_{\rm c}=0.129^{+0.019}_{-0.030}$ of the layers of non-spherical nuclei (nuclear pasta) in the crust.
It is now possible to make equation of state measurements on compressed matter up to pressures in excess of 1 TPa, by carrying out shock compression studies on samples placed in the vicinity of underground explosions [1]. While these shock wave experiments measure very hot samples, current research in laser implosion techniques is aimed at reaching comparable compressions with much lower final temperatures.† This increasing experimental access to TPa and higher pressures provides the theoretician with an impetus to examine the problem of calculating very high pressure equations of state. To date, almost all theoretical determinations in this range have been based on statistical, Thomas-Fermi models [2–4]. The Soviet shock compression work, for example, uses a comparative measurement technique which depends critically on a simplistic extrapolation of experimental data below 1 TPa over an order of magnitude in pressure to the predictions of statistical models above 10 TPa. The major disadvantage of the statistical models is that they ignore the electron shell structure of the atoms. Attempts to correct these models [5] must be considered tentative. A more satisfactory treatment of electrons in solids rigorously including shell structure is the self-consistent augmented-plane-wave (APW) method. This method has become widely used in recent years to calculate T = 0 isotherms and cohesive energies of metals.
On May 24th, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 Mpc and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.
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