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Articles 1 - 24 of 24
Full-Text Articles in Physics
Constructing A Magneto-Optical Trap For Cold Atom Trapping, Eric S. Muckley
Constructing A Magneto-Optical Trap For Cold Atom Trapping, Eric S. Muckley
Physics
A magneto-optical trap, or MOT, is a device that traps atoms between three pairs of opposing perpendicular laser beams for cooling the atoms to temperatures near absolute zero. The MOT uses Doppler cooling and a magnetic quadrupole field to trap the atoms; in our case, Rb87 atoms. In the future, the MOT will be used in experiments pertaining to the advancement of quantum computing. In this paper, I explain some of the processes required for construction and operation of the MOT.
Developing A B-Jet Tagging Algorithm For Alice: Lessons From Cdf, Paul Chester-John Carlson
Developing A B-Jet Tagging Algorithm For Alice: Lessons From Cdf, Paul Chester-John Carlson
Physics
This paper compares the detectors and algorithms developed and used at both A Large Ion Collider Experiment (ALICE) and the Collider Detector at Fermilab (CDF). We found that the detectors share many similarities in data collection and analysis methods and that by adapting algorithms that have been tested and used at CDF, ALICE could augment its existing algorithms. The algorithms formed from this adaptation will help ALICE isolate b-jets quickly and explore the quark-gluon plasma, ultimately expanding our understanding of the strong nuclear force and its role in the evolution of our universe.
The Lick Agn Monitoring Project: Broad-Line Region Radii And Black Hole Masses From Reverberation Mapping Of HSs, Misty C. Bentz, Jonelle L. Walsh, Aaron J. Barth, Nairn Baliber, Vardha N. Bennert, Gabriela Canalizo, Alexei V. Filippenko, Mohan Ganeshalingam, Elinor L. Gates, Jenny E. Greene, Marton G. Hidas, Kyle D. Hiner, Nicholas Lee, Weidong Li, Matthew A. Malkan, Takeo Minezaki, Yu Sakata, Frank J.D. Serduke, Jeffrey M. Silverman, Thea N. Steele, Daniel Stern, Rachel A. Street, Carol E. Thornton, Tommaso Treu, Xiaofeng Wang, Jong-Hak Woo, Yuzuru Yoshii
The Lick Agn Monitoring Project: Broad-Line Region Radii And Black Hole Masses From Reverberation Mapping Of HSs, Misty C. Bentz, Jonelle L. Walsh, Aaron J. Barth, Nairn Baliber, Vardha N. Bennert, Gabriela Canalizo, Alexei V. Filippenko, Mohan Ganeshalingam, Elinor L. Gates, Jenny E. Greene, Marton G. Hidas, Kyle D. Hiner, Nicholas Lee, Weidong Li, Matthew A. Malkan, Takeo Minezaki, Yu Sakata, Frank J.D. Serduke, Jeffrey M. Silverman, Thea N. Steele, Daniel Stern, Rachel A. Street, Carol E. Thornton, Tommaso Treu, Xiaofeng Wang, Jong-Hak Woo, Yuzuru Yoshii
Physics
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range ~106-107 M ☉ and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad Hβ emission. We present here the light curves for all …
The Lick Agn Monitoring Project: Photometric Light Curves And Optical Variability Characteristics, Jonelle L. Walsh, Takeo Minezaki, Misty C. Bentz, Aaron J. Barth, Nairn Baliber, Weidong Li, Daniel Stern, Vardha Nicola Bennert, Timothy M. Brown, Gabriela Canalizo, Alexei V. Filippenko, Elinor L. Gates, Jenny E. Greene, Matthew A. Malkan, Yu Sakata, Rachel A. Street, Tommaso Treu, Jong-Hak Woo, Yuzuru Yoshii
The Lick Agn Monitoring Project: Photometric Light Curves And Optical Variability Characteristics, Jonelle L. Walsh, Takeo Minezaki, Misty C. Bentz, Aaron J. Barth, Nairn Baliber, Weidong Li, Daniel Stern, Vardha Nicola Bennert, Timothy M. Brown, Gabriela Canalizo, Alexei V. Filippenko, Elinor L. Gates, Jenny E. Greene, Matthew A. Malkan, Yu Sakata, Rachel A. Street, Tommaso Treu, Jong-Hak Woo, Yuzuru Yoshii
Physics
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 106-107 M ☉, as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the …
Galaxy Zoo Green Peas: Discovery Of A Class Of Compact Extremely Star-Forming Galaxies, Carolin Cardamone, Kevin Schawinski, Marc Sarzi, Steven P. Bamford, Vardha N. Bennert, C. M. Urry, Chris Lintott, William C. Keel, John Parejko, Robert C. Nichol, Daniel Thomas, Dan Andreescu, Phil Murray, M. Jordan Raddick, Anže Slosar, Alex Szalay, Jan Vandenberg
Galaxy Zoo Green Peas: Discovery Of A Class Of Compact Extremely Star-Forming Galaxies, Carolin Cardamone, Kevin Schawinski, Marc Sarzi, Steven P. Bamford, Vardha N. Bennert, C. M. Urry, Chris Lintott, William C. Keel, John Parejko, Robert C. Nichol, Daniel Thomas, Dan Andreescu, Phil Murray, M. Jordan Raddick, Anže Slosar, Alex Szalay, Jan Vandenberg
Physics
We investigate a class of rapidly growing emission line galaxies, known as ‘Green Peas’, first noted by volunteers in the Galaxy Zoo project because of their peculiar bright green colour and small size, unresolved in Sloan Digital Sky Survey imaging. Their appearance is due to very strong optical emission lines, namely [O iii]λ5007 Å, with an unusually large equivalent width of up to ∼1000 Å. We discuss a well-defined sample of 251 colour-selected objects, most of which are strongly star forming, although there are some active galactic nuclei interlopers including eight newly discovered narrow-line Seyfert 1 galaxies. The star-forming Peas …
Assessing The Merits Of The Ctbt, David W. Hafemeister
Assessing The Merits Of The Ctbt, David W. Hafemeister
Physics
The Treaty on the Non-Proliferation of Nuclear Weapons and the nonproliferation regime have been weakened; perhaps no other issue demonstrates this as dramatically as the status of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the ratification of which the U.S. Senate rejected in October 1999. Despite the U.S. rejection, the test ban has strong international support—the most recent vote to promote the CTBT in the UN General Assembly passed overwhelmingly, with 175 votes to 1 (the United States) and three abstentions. The Obama administration favors U.S. ratification of the CTBT, but this is no guarantee that Washington will ratify the test ban. …
Galaxy Zoo: ‘Hanny's Voorwerp’, A Quasar Light Echo?, Chris J. Lintott, Kevin Schawinski, William Keel, Hanny Van Arkel, Nicola Bennert, Edward Edmondson, Daniel Thomas, Daniel J.B. Smith, Peter D. Herbert, Matt J. Jarvis, Shanil Virani, Dan Andreescu, Steven P. Bamford, Kate Land, Phil Murray, Robert C. Nichol, M. Jordan Raddick, Anže Slosar, Alex Azalay, Jan Vandenberg
Galaxy Zoo: ‘Hanny's Voorwerp’, A Quasar Light Echo?, Chris J. Lintott, Kevin Schawinski, William Keel, Hanny Van Arkel, Nicola Bennert, Edward Edmondson, Daniel Thomas, Daniel J.B. Smith, Peter D. Herbert, Matt J. Jarvis, Shanil Virani, Dan Andreescu, Steven P. Bamford, Kate Land, Phil Murray, Robert C. Nichol, M. Jordan Raddick, Anže Slosar, Alex Azalay, Jan Vandenberg
Physics
We report the discovery of an unusual object near the spiral galaxy IC 2497, discovered by visual inspection of the Sloan Digital Sky Survey (SDSS) as part of the Galaxy Zoo project. The object, known as Hanny's Voorwerp, is bright in the SDSS g band due to unusually strong [O iii]4959, 5007 emission lines. We present the results of the first targeted observations of the object in the optical, ultraviolet and X-ray, which show that the object contains highly ionized gas. Although the line ratios are similar to extended emission-line regions near luminous active galactic nucleus (AGN), the source of …
Input To The Nas Ctbt Study, David Hafemeister
De Vries Behavior In Smectics Near A Biaxiality Induced Smectic A - Smectic C Tricritical Point, Karl Saunders
De Vries Behavior In Smectics Near A Biaxiality Induced Smectic A - Smectic C Tricritical Point, Karl Saunders
Physics
We show that a generalized Landau theory for the smectic A and C phases exhibits a biaxiality induced AC tricritical point. Proximity to this tricritical point depends on the degree of orientational order in the system; for sufficiently large orientational order the AC transition is 3D XY-like, while for sufficiently small orientational order, it is either tricritical or 1st order. We investigate each of the three types of AC transitions near tricriticality and show that for each type of transition, small orientational order implies de Vries behavior in the layer spacing, an unusually small layer contraction. This result is consistent …
Ctbt Evasion Scenarios: Possible Or Probable?, David W. Hafemeister
Ctbt Evasion Scenarios: Possible Or Probable?, David W. Hafemeister
Physics
No abstract provided.
Contributing Efforts In The Search For Neutrinoless Double Beta Decay, Laura Christine Sparks
Contributing Efforts In The Search For Neutrinoless Double Beta Decay, Laura Christine Sparks
Physics
Cryogenic Underground Observatory for Rare Events (CUORE) will be part of the next generation of detectors used to search for neutrinoless double beta decay (0νββ). Located in Assergi, Italy at the Gran Sasso National Laboratory (LNGS), CUORE will be a large cryogenic bolometer composed of 988 tellurium dioxide (TeO2) detectors with a total mass of 750 kg, and will search for 0νββ in 130Te. As the experiment will monitor the extremely rare event of 0νββ, all factors contributing to background need to be minimized to effectively increase the sensitivity. I assisted the LNGS researchers over the summer of 2008 by …
De Vries Behavior Of The Electroclinic Effect In The Smectic-A* Phase Near A Biaxiality-Induced Smectic-A*–Smectic-C* Tricritical Point, Karl Saunders
De Vries Behavior Of The Electroclinic Effect In The Smectic-A* Phase Near A Biaxiality-Induced Smectic-A*–Smectic-C* Tricritical Point, Karl Saunders
Physics
Using a generalized Landau theory involving orientational, layering, tilt, and biaxial order parameters we analyze the smectic-A* and smectic-C* (Sm-A*-Sm-C*) transitions, showing that a combination of small orientational order and large layering order leads to Sm-A*-Sm-C* transitions that are either continuous and close to tricriticality or first order. The model predicts that in such systems the increase in birefringence upon entry to the Sm-C* phase will be especially rapid. It also predicts that the change in layer spacing at the Sm-A*-Sm-C* transition will be proportional to the orientational order. These are two hallmarks of Sm-A*-Sm-C* transitions in de Vries materials. …
Nuclear Testing And Proliferation – An Inextricable Connection, Thomas Graham Jr., David W. Hafemeister
Nuclear Testing And Proliferation – An Inextricable Connection, Thomas Graham Jr., David W. Hafemeister
Physics
No abstract provided.
Capabilities Of The Ims Seismic Auxiliary Network, David W. Hafemeister
Capabilities Of The Ims Seismic Auxiliary Network, David W. Hafemeister
Physics
No abstract provided.
Ctbt Space-Based Monitoring: Interferometric Synthetic Aperture Radar And National Technical Means, David W. Hafemeister
Ctbt Space-Based Monitoring: Interferometric Synthetic Aperture Radar And National Technical Means, David W. Hafemeister
Physics
No abstract provided.
Chiral Sedimentation Of Extended Objects In Viscous Media, Nathan W. Krapf, Thomas A. Witten, Nathan C. Keim
Chiral Sedimentation Of Extended Objects In Viscous Media, Nathan W. Krapf, Thomas A. Witten, Nathan C. Keim
Physics
We study theoretically the chirality of a generic rigid object’s sedimentation in a fluid under gravity in the low Reynolds number regime. We represent the object as a collection of small Stokes spheres or stokeslets and the gravitational force as a constant point force applied at an arbitrary point of the object. For a generic configuration of stokeslets and forcing point, the motion takes a simple form in the nearly free draining limit where the stokeslet radius is arbitrarily small. In this case, the internal hydrodynamic interactions between stokeslets are weak, and the object follows a helical path while rotating …
Memory-Encoding Vibrations In A Disconnecting Air Bubble, Laura E. Schmidt, Nathan C. Keim, Wendy W. Zhang, Sidney R. Nagel
Memory-Encoding Vibrations In A Disconnecting Air Bubble, Laura E. Schmidt, Nathan C. Keim, Wendy W. Zhang, Sidney R. Nagel
Physics
Many nonlinear processes, such as the propagation of waves over an ocean or the transmission of light pulses down an optical fibre1, are integrable in the sense that the dynamics has as many conserved quantities as there are independent variables. The result is a time evolution that retains a complete memory of the initial state. In contrast, the nonlinear dynamics near a finite-time singularity, in which physical quantities such as pressure or velocity diverge at a point in time, is believed to evolve towards a universal form, one independent of the initial state2. The break-up of a water drop in …
A Search For H2O Megamasers In High-Z Type-2 Active Galactic Nuclei, Vardha N. Bennert, Richard Barvainis, Christian Henkel, Robert Antonucci
A Search For H2O Megamasers In High-Z Type-2 Active Galactic Nuclei, Vardha N. Bennert, Richard Barvainis, Christian Henkel, Robert Antonucci
Physics
We report a search for H2O megamasers in 274 SDSS type-2 active galactic nuclei (AGNs; 0.3 <z< 0.83), half of which can be classified as type-2 quasi-stellar objects (QSOs) from their [O III] 5007 luminosity, using the Robert C. Byrd Green Bank Telescope (GBT) and the Effelsberg 100 m radio telescope. Apart from the detection of the extremely luminous water vapor megamaser SDSS J080430.99+360718.1, already reported by Barvainis & Antonucci, we do not find any additional line emission. This high rate of nondetections is compared to the water maser luminosity function created from the 78 water maser galaxies known to date and its extrapolation toward the higher luminosities of "gigamasers" that we would have been able to detect given the sensitivity of our survey. The properties of the known water masers are summarized and discussed with respect to the nature of high-z type-2 AGNs and megamasers in general. In the Appendix, we list 173 additional objects (mainly radio galaxies, but also QSOs and galaxies) that were observed with the GBT, the Effelsberg 100 m radio telescope, or Arecibo Observatory without leading to the detection of water maser emission.
Review Of The 2008 Aps Energy Study, Energy Future: Think Efficiency, David W. Hafemeister
Review Of The 2008 Aps Energy Study, Energy Future: Think Efficiency, David W. Hafemeister
Physics
No abstract provided.
Small-Volume U-Pb Zircon Geochronology By Laser Ablation-Multicollector-Icp-Ms, Scott Johnston, George Gehrels, Victor Valencia, Joaquin Ruiz
Small-Volume U-Pb Zircon Geochronology By Laser Ablation-Multicollector-Icp-Ms, Scott Johnston, George Gehrels, Victor Valencia, Joaquin Ruiz
Physics
U–Pb zircon geochronology is hampered by problems acquiring meaningful geologic ages on zoned grains that retain isotope signatures from multiple growth or thermal events. We present a new method using laser ablation-multicollector-inductively coupled plasma-mass spectrometry to overcome complications associated with intricately zoned zircon crystals through in situ sampling of zircon volumes as small as 12–14 µm in diameter by 4–5 µm in depth (< 3 ng of zircon). Using Channeltron multipliers to monitor Pb intensities in conjunction with a total ion counting method and errors calculated as function of the number of counts, the small-volume technique reproduced published ages on eight Mesoproterozoic–Cretaceous secondary zircon standards precise and accurate within 2%, and an age not, vert, similar 1 Ma too young on a Oligocene-aged grain. Two initial applications of the small-volume technique — the detrital zircon provenance of fine-grained mudstones and shales and the creation of zircon U–Pb age maps to investigate the detrital and metamorphic history of a granulite-facies paragneiss — demonstrate the utility of this technique to a variety of geologic problems and confirm the viability of laser ablation-multicollector-inductively coupled plasma-mass spectrometry as a tool for high spatial resolution U–Pb geochronology.
The Discovery Of Magnetotactic/Magnetosensitive Bacteria, Richard B. Frankel
The Discovery Of Magnetotactic/Magnetosensitive Bacteria, Richard B. Frankel
Physics
No abstract provided.
Application Of Hertz Vector Diffraction Theory To The Diffraction Of Focused Gaussian Beams And Calculations Of Focal Parameters, Glen D. Gillen, Kendra Baughman, Shekhar Guha
Application Of Hertz Vector Diffraction Theory To The Diffraction Of Focused Gaussian Beams And Calculations Of Focal Parameters, Glen D. Gillen, Kendra Baughman, Shekhar Guha
Physics
Hertz vector diffraction theory is applied to a focused TEM00 Gaussian light field passing through a circular aperture. The resulting theoretical vector field model reproduces plane-wave diffractive behavior for severely clipped beams, expected Gaussian beam behavior for unperturbed focused Gaussian beams as well as unique diffracted-Gaussian behavior between the two regimes. The maximum intensity obtainable and the width of the beam in the focal plane are investigated as a function of the clipping ratio between the aperture radius and the beam width in the aperture plane.
High-Temperature Deformation During Continental-Margin Subduction & Exhumation: The Ultrahigh-Pressure Western Gneiss Region Of Norway, Bradley R. Hacker, Torgeir B. Andersen, Scott Johnston, Andrew R.C. Kylander-Clark, Emily M. Peterman, Emily O. Walsh, David Young
High-Temperature Deformation During Continental-Margin Subduction & Exhumation: The Ultrahigh-Pressure Western Gneiss Region Of Norway, Bradley R. Hacker, Torgeir B. Andersen, Scott Johnston, Andrew R.C. Kylander-Clark, Emily M. Peterman, Emily O. Walsh, David Young
Physics
A new dataset for the high-pressure to ultrahigh-pressure Western Gneiss Region allows the definition of distinct structural and petrological domains. Much of the study area is an E-dipping homocline with E-plunging lineations that exposes progressively deeper, more strongly deformed, more eclogite-rich structural levels westward. Although eclogites crop out across the WGR, Scandian deformation is weak and earlier structures are well preserved in the southeastern half of the study area. The Scandian reworking increases westward, culminating in strong Scandian fabrics with only isolated pockets of older structures; the dominant Scandian deformation was coaxial E–W stretching. The sinistrally sheared Møre–Trøndelag Fault Complex …
Magnetosomes And Magneto-Aerotaxis, Richard B. Frankel, Dennis A. Bazylinski
Magnetosomes And Magneto-Aerotaxis, Richard B. Frankel, Dennis A. Bazylinski
Physics
Magnetotactic bacteria orient and migrate along geomagnetic field lines. Magneto-aerotaxis increases the efficiency of respiring microaerophilic cells to efficiently find and maintain a position at a preferred microaerobic oxygen concentration. Magneto-aerotaxis could also facilitate access to regions of higher nutrient and electron acceptor concentration via periodic excursions above and below the preferred oxygen concentration level.