5
5.0
Apr 12, 2021
04/21
by
J Madsen (jtmcelf)
data
eye 5
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comment 0
halvpart printes to gange og trykkes sammen til en stjerne. kan evt. bestykkes med 5 led lys, et i hvert "ben"
Topics: thingiverse, stl, Other
65
65
Sep 22, 2013
09/13
by
G. J. Madsen
texts
eye 65
favorite 0
comment 0
The Wisconsin H-Alpha Mapper (WHAM) has completed a velocity-resolved map of diffuse H-alpha emission of the entire northern sky, providing the first comprehensive picture of both the distribution and kinematics of diffuse ionized gas in the Galaxy. WHAM continues to advance our understanding of the physical conditions of the warm ionized medium through observations of other optical emission lines throughout the Galactic disk and halo. We discuss some highlights from the survey, including an...
Source: http://arxiv.org/abs/astro-ph/0310330v1
55
55
Sep 22, 2013
09/13
by
G. J. Madsen
texts
eye 55
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comment 0
We report on observations of several optical emission lines toward a variety of newly revealed faint, large-scale H-alpha-emitting structures in the warm ionized medium (WIM) of the Galaxy. The lines include [N II] 6583, [N II] 5755, [S II] 6716, [O III] 5007, and He I 5876 and were obtained with the Wisconsin H-Alpha Mapper (WHAM) toward sightlines that probe both large filamentary features and the more diffuse WIM, from the outer Perseus spiral arm to the inner Galaxy. These emission lines...
Source: http://arxiv.org/abs/astro-ph/0409476v1
50
50
Sep 20, 2013
09/13
by
D. M. Jensen; J. Madsen
texts
eye 50
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Strangelets with non-zero entropy are studied within the MIT bag model. Explicit account is taken of the constraints that strangelets must be color neutral and have a fixed total momentum. In general, masses increase with increasing entropy per baryon, and the constraints work so as to increase masses further. This has an important destabilizing effect on strangelets produced in ultrarelativistic heavy ion collisions.
Source: http://arxiv.org/abs/hep-ph/9507308v1
4
4.0
Jun 30, 2018
06/18
by
Keith W. Bannister; Greg. J. Madsen
texts
eye 4
favorite 0
comment 0
The recent detection of Fast Radio Bursts (FRBs) has generated strong interest in identifying the origin of these bright, non-repeating, highly dispersed pulses. The principal limitation in understanding the origin of these bursts is the lack of reliable distance estimates; their high dispersion measures imply that they may be at cosmological distances ($0.1 < z < 1.0$). Here we discuss new distance constraints to the FRB010621 (a.k.a J1852$-$08) first reported by Keane. We use velocity...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1402.0268
57
57
Sep 18, 2013
09/13
by
G. J. Madsen; R. J. Reynolds
texts
eye 57
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comment 0
Halpha and Hbeta spectroscopy with the Wisconsin H-Alpha Mapper (WHAM) reveals a strong concentration of high velocity emission in a ~ 5 by 5 deg area centered near (l.b) = (27,-3), known as the Scutum Cloud. The high velocities imply that we are detecting optical emission from near the plane of the Galaxy out to the tangent point at heliocentric distances of D \gtrsim 6 kpc, assuming the gas participates in circular Galactic rotation. The ratio of the Halpha to Hbeta emission as a function of...
Source: http://arxiv.org/abs/astro-ph/0505485v1
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63
Jul 20, 2013
07/13
by
M. J. Madsen; C. H. Gorman
texts
eye 63
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comment 0
We present the design of a new type of compact toroidal, or "halo", ion trap. Such traps may be useful for mass spectrometry, studying small Coulomb cluster rings, quantum information applications, or other quantum simulations where a ring topology is of interest. We present results from a Monte Carlo optimization of the trap design parameters using finite-element analysis simulations that minimizes higher-order anharmonic terms in the trapping pseudopotential, while maintaining...
Source: http://arxiv.org/abs/1007.2332v1
3
3.0
Jun 30, 2018
06/18
by
M. Wiesenberger; J. Madsen; A. Kendl
texts
eye 3
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We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is...
Topics: Physics, Plasma Physics
Source: http://arxiv.org/abs/1404.0546
5
5.0
Jun 29, 2018
06/18
by
M. Held; M. Wiesenberger; J. Madsen; A. Kendl
texts
eye 5
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comment 0
Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic finite Larmor radius effects. We find that the maximal radial blob velocity increases with the square root of the initial pressure perturbation and that a finite Larmor radius contributes to highly...
Topics: Physics, Plasma Physics
Source: http://arxiv.org/abs/1602.04999
52
52
Jul 20, 2013
07/13
by
G. J. Madsen; R. J. Reynolds; L. M. Haffner
texts
eye 52
favorite 0
comment 0
We report on observations of several optical emission lines toward a variety of newly revealed faint, large-scale Halpha-emitting regions in the Galaxy. The lines include [NII] 6583, [NII] 5755, [SII] 6716, [OIII] 5007, and HeI 5876 obtained with the Wisconsin H-Alpha Mapper (WHAM) toward sightlines that probe superbubbles, high latitude filamentary features, and the more diffuse warm ionized medium (WIM). Our observations include maps covering thousands of square degrees toward the well-known...
Source: http://arxiv.org/abs/astro-ph/0609558v1
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48
Sep 21, 2013
09/13
by
Lisa Harvey-Smith; Gregory J. Madsen; Bryan M. Gaensler
texts
eye 48
favorite 0
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We present a study of the line-of-sight magnetic fields in five large-diameter Galactic HII regions. Using the Faraday rotation of background polarized radio sources, as well as dust-corrected H-alpha surface brightness as a probe of electron density, we estimated the strength and orientation of the magnetic field along 93 individual sight-lines through the HII regions. Each of the HII regions displayed a coherent magnetic field. The magnetic field strength (line-of-sight component) in the...
Source: http://arxiv.org/abs/1106.0931v1
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85
Sep 21, 2013
09/13
by
Z. J. Rohrbach; T. R. Buresh; M. J. Madsen
texts
eye 85
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The use of compressed air cannons in an undergraduate lab provides a way to illustrate the cooperation of diverse physics concepts, such as conservation of momentum, the work-kinetic energy theorem, expansion of gas, air drag, and elementary Newtonian mechanics. However, recent proposals have disagreed as to whether the expansion of the gas in the cannon should be modeled as an adiabatic or an isothermal process. We built an air cannon that utilized a diaphragm valve to release our pressurized...
Source: http://arxiv.org/abs/1106.2803v1
57
57
Sep 20, 2013
09/13
by
R. J. Reynolds; G. J. Madsen; S. H. Moseley
texts
eye 57
favorite 0
comment 0
Using the Wisconsin H-Alpha Mapper (WHAM), we have measured at high spectral resolution and high signal-to-noise the profile of the scattered solar Mg I 5184 absorption line in the zodiacal light. The observations were carried out toward 49 directions that sampled the ecliptic equator from solar elongations of 48\dg (evening sky) to 334\dg (morning sky) plus observations near +47\dg and +90\dg ecliptic latitude. The spectra show a clear prograde kinematic signature that is inconsistent with...
Source: http://arxiv.org/abs/astro-ph/0405529v1
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42
Sep 22, 2013
09/13
by
R. J. Reynolds; L. M. Haffner; G. J. Madsen
texts
eye 42
favorite 0
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The Wisconsin H-Alpha Mapper (WHAM) is a high throughput Fabry-Perot facility developed specifically to detect and explore the warm, ionized component of the interstellar medium at high spectral resolution. It began operating at Kitt Peak, Arizona in 1997 and has recently completed the WHAM Northern Sky Survey (WHAM-NSS), providing the first global view of the distribution and kinematics of the warm, diffuse H II in the Milky Way. This H-alpha survey reveals a complex spatial and kinematic...
Source: http://arxiv.org/abs/astro-ph/0201392v1
146
146
Jul 20, 2013
07/13
by
D. L. Moehring; M. J. Madsen; B. B. Blinov; C. Monroe
texts
eye 146
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We report the measurement of a Bell inequality violation with a single atom and a single photon prepared in a probabilistic entangled state. This is the first demonstration of such a violation with particles of different species. The entanglement characterization of this hybrid system may also be useful in quantum information applications.
Source: http://arxiv.org/abs/quant-ph/0406048v1
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51
Sep 23, 2013
09/13
by
R. J. Reynolds; V. Chaudhary; G. J. Madsen; L. M. Haffner
texts
eye 51
favorite 0
comment 0
We have identified 85 regions of enhanced H-Alpha emission at |b| > 10 degrees subtending approximately 1 degree or less on the Wisconsin H-Alpha Mapper (WHAM) sky survey. These high latitude ``WHAM point sources'' have H-Alpha fluxes of 10^{-11} to 10^{-9} erg cm^-2 s^-1, radial velocities within about 70 km/s of the LSR, and line widths that range from less than 20 km/s to about 80 km/s (FWHM). Twenty nine of these enhancements are not identified with either cataloged nebulae or hot stars...
Source: http://arxiv.org/abs/astro-ph/0411120v1
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54
Sep 22, 2013
09/13
by
D. Pierini; K. D. Gordon; A. N. Witt; G. J. Madsen
texts
eye 54
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We present results of new Monte Carlo calculations made with the DIRTY code of radiative transfer of stellar and scattered radiation for a dusty giant late-type galaxy like the Milky Way, which illustrate the effect of the attenuation of stellar light by internal dust on the integrated photometry of the individual bulge and disk components. Here we focus on the behavior of the attenuation function, the color excess, and the fraction of light scattered or directly transmitted towards the outside...
Source: http://arxiv.org/abs/astro-ph/0409183v1
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119
Sep 21, 2013
09/13
by
B. M. Gaensler; G. J. Madsen; S. Chatterjee; S. A. Mao
texts
eye 119
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We present a new joint analysis of pulsar dispersion measures and diffuse H-alpha emission in the Milky Way, which we use to derive the density, pressure and filling factor of the thick disk component of the warm ionised medium (WIM) as a function of height above the Galactic disk. By excluding sightlines at low Galactic latitude that are contaminated by HII regions and spiral arms, we find that the exponential scale-height of free electrons in the diffuse WIM is 1830 (+120, -250) pc, a factor...
Source: http://arxiv.org/abs/0808.2550v1
57
57
Sep 19, 2013
09/13
by
David J. Frew; Greg J. Madsen; Simon J. O'Toole; Quentin A. Parker
texts
eye 57
favorite 0
comment 0
The emission nebula around the subdwarf B (sdB) star PHL 932 is currently classified as a planetary nebula (PN) in the literature. Based on a large body of multi-wavelength data, both new and previously published, we show here that this low-excitation nebula is in fact a small Stromgren sphere (HII region) in the interstellar medium around this star. We summarise the properties of the nebula and its ionizing star, and discuss its evolutionary status. We find no compelling evidence for close...
Source: http://arxiv.org/abs/0910.2078v1
90
90
Sep 18, 2013
09/13
by
M. J. Madsen; W. K. Hensinger; D. Stick; J. A. Rabchuk; C. Monroe
texts
eye 90
favorite 0
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We describe a novel high aspect ratio radiofrequency linear ion trap geometry that is amenable to modern microfabrication techniques. The ion trap electrode structure consists of a pair of stacked conducting cantilevers resulting in confining fields that take the form of fringe fields from parallel plate capacitors. The confining potentials are modeled both analytically and numerically. This ion trap geometry may form the basis for large scale quantum computers or parallel quadrupole mass...
Source: http://arxiv.org/abs/quant-ph/0401047v1
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45
Sep 22, 2013
09/13
by
R. J. Reynolds; L. M. Haffner; G. J. Madsen; K. Wood; A. S. Hill
texts
eye 45
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Thick layers of warm, low density ionized hydrogen (i.e., the warm ionized medium or WIM) in spiral galaxies provide direct evidence for an interaction between the disk and halo. The wide-spread ionization implies that a significant fraction of the Lyman continuum photons from O stars, produced primarily in isolated star forming regions near the midplane and often surrounded by opaque clouds of neutral hydrogen, is somehow able to propagate large distances through the disk and into the halo....
Source: http://arxiv.org/abs/0812.4303v1
75
75
Sep 18, 2013
09/13
by
A. S. Hill; R. J. Reynolds; L. M. Haffner; K. Wood; G. J. Madsen
texts
eye 75
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We review the observational evidence that the warm ionized medium (WIM) is a major and physically distinct component of the Galactic interstellar medium. Although up to ~20% of the faint, high-latitude H-alpha emission in the Milky Way may be scattered light emitted in midplane H II regions, recent scattered light models do not effectively challenge the well-established properties of the WIM.
Source: http://arxiv.org/abs/1211.0369v1
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41
Sep 18, 2013
09/13
by
Vanessa A. Moss; Naomi M. McClure-Griffiths; Robert Braun; Alex S. Hill; Greg J. Madsen
texts
eye 41
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We report on the discovery of a new Galactic supershell, GSH 006-15+7, from the Galactic All Sky Survey data. Observed and derived properties are presented and we find that GSH 006-15+7 is one of the nearest physically large supershells known, with dimensions of ~ 780 x 520 pc at a distance of ~ 1.5 kpc. The shell wall appears in HI emission at b ~ -6.5 deg. We use this feature along with HISA diagnostics to estimate an optical depth of tau ~ 3, a spin temperature of ~ 40 K and a swept-up mass...
Source: http://arxiv.org/abs/1201.2700v1
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49
Sep 23, 2013
09/13
by
G. J. Madsen; R. J. Reynolds; L. M. Haffner; S. L. Tufte; Philip R. Maloney
texts
eye 49
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comment 0
We have used the Wisconsin H-Alpha Mapper (WHAM) to observe the spatially extended distribution of ionized hydrogen in M31 beyond the stellar disk. We obtained five sets of observations, centered near the photometric major axis of M31, that extend from the center of the galaxy to just off the edge of the southwestern HI disk. Beyond the bright stellar disk, but within the HI disk, weak H-alpha is detected with an intensity I(H-alpha) = 0.05 (+0.01 / -0.02) Rayleighs. Since M31 is inclined 77...
Source: http://arxiv.org/abs/astro-ph/0109102v1
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46
Sep 19, 2013
09/13
by
S. L. Tufte; J. D. Wilson; G. J. Madsen; L. M. Haffner; R. J. Reynolds
texts
eye 46
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It has been suggested that high velocity clouds may be distributed throughout the Local Group and are therefore not in general associated with the Milky Way galaxy. With the aim of testing this hypothesis, we have made observations in the H-alpha line of high velocity clouds selected as the most likely candidates for being at larger than average distances. We have found H-alpha emission from 4 out of 5 of the observed clouds, suggesting that the clouds under study are being illuminated by a...
Source: http://arxiv.org/abs/astro-ph/0206198v1
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40
Sep 18, 2013
09/13
by
G. J. Madsen; D. J. Frew; Q. A. Parker; R. J. Reynolds; L. M. Haffner
texts
eye 40
favorite 0
comment 0
Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB wind is returned to the interstellar medium. However, the low surface brightness and spatially extended emission of large PNe have made accurate measurements of line fluxes difficult with traditional long-slit spectroscopic techniques. Furthermore,...
Source: http://arxiv.org/abs/astro-ph/0605114v1
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42
Sep 20, 2013
09/13
by
J. S. Gallagher; G. J. Madsen; R. J. Reynolds; E. K. Grebel; T. A. Smecker-Hane
texts
eye 42
favorite 0
comment 0
The Wisconsin H Alpha Mapper has been used to set the first deep upper limits on the intensity of diffuse H alpha emission from warm ionized gas in the Local Group dwarf spheroidal galaxies (dSphs) Draco and Ursa Minor. Assuming a velocity dispersion of 15 km/s for the ionized gas, we set limits for the H alpha intensity of less or equal to 0.024 Rayleighs and less or equal to 0.021 Rayleighs for the Draco and Ursa Minor dSphs, respectively, averaged over our 1 degree circular beam. Adopting a...
Source: http://arxiv.org/abs/astro-ph/0301228v1
6
6.0
Jun 30, 2018
06/18
by
A H. Nielsen; G. S. Xu; J. Madsen; V. Naulin; J. Juul Rasmussen; B. N. Wan
texts
eye 6
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The transition dynamics from the low (L) to the high (H) confinement mode in magnetically confined plasmas is investigated using a first-principles four-field fluid model. Numerical results are in close agreement with measurements from the Experimental Advanced Superconducting Tokamak - EAST. Particularly, the slow transition with an intermediate dithering phase is well reproduced by the numerical solutions. Additionally, the model reproduces the experimentally determined L-H transition power...
Topics: Physics, Plasma Physics
Source: http://arxiv.org/abs/1409.3186
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47
Sep 19, 2013
09/13
by
B. B. Blinov; R. N. Kohn Jr.; M. J. Madsen; P. Maunz; D. L. Moehring; C. Monroe
texts
eye 47
favorite 0
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We demonstrate broadband laser cooling of atomic ions in an rf trap using ultrafast pulses from a modelocked laser. The temperature of a single ion is measured by observing the size of a time-averaged image of the ion in the known harmonic trap potential. While the lowest observed temperature was only about 1 K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images.
Source: http://arxiv.org/abs/quant-ph/0507074v2
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52
Sep 20, 2013
09/13
by
P. Maunz; D. L. Moehring; M. J. Madsen; R. N. Kohn Jr.; K. C. Younge; C. Monroe
texts
eye 52
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We collect the fluorescence from two trapped atomic ions, and measure quantum interference between photons emitted from the ions. The interference of two photons is a crucial component of schemes to entangle atomic qubits based on a photonic coupling. The ability to preserve the generated entanglement and to repeat the experiment with the same ions is necessary to implement entangling quantum gates between atomic qubits, and allows the implementation of protocols to efficiently scale to larger...
Source: http://arxiv.org/abs/quant-ph/0608047v1
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49
Sep 19, 2013
09/13
by
N. M. McClure-Griffiths; G. J. Madsen; B. M. Gaensler; D. McConnell; D. H. F. M. Schnitzeler
texts
eye 49
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Using a recent catalogue of extragalactic Faraday rotation derived from the NRAO VLA Sky Survey we have found an agreement between Faraday rotation structure and the HI emission structure of a High Velocity Cloud (HVC) associated with the Leading Arm of the Magellanic System. We suggest that this morphological agreement is indicative of Faraday rotation through the HVC. Under this assumption we have used 48 rotation measures through the HVC, together with estimates of the electron column...
Source: http://arxiv.org/abs/1009.5849v1
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47
Sep 22, 2013
09/13
by
L. -M. Duan; M. J. Madsen; D. L. Moehring; P. Maunz; R. N. Kohn Jr.; C. Monroe
texts
eye 47
favorite 0
comment 0
We propose a scheme to perform probabilistic quantum gates on remote trapped atom qubits through interference of optical frequency qubits. The method does not require localization of the atoms to the Lamb-Dicke limit, and is not sensitive to interferometer phase instabilities. Such probabilistic gates can be used for scalable quantum computation.
Source: http://arxiv.org/abs/quant-ph/0603285v1
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53
Sep 22, 2013
09/13
by
M. J. Madsen; D. L. Moehring; P. Maunz; R. N. Kohn Jr.; L. -M. Duan; C. Monroe
texts
eye 53
favorite 0
comment 0
We demonstrate ultrafast coherent coupling between an atomic qubit stored in a single trapped cadmium ion and a photonic qubit represented by two resolved frequencies of a photon. Such ultrafast coupling is crucial for entangling networks of remotely-located trapped ions through photon interference, and is also a key component for realizing ultrafast quantum gates between Coulomb-coupled ions.
Source: http://arxiv.org/abs/quant-ph/0603258v2
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70
Sep 22, 2013
09/13
by
L. M. Haffner; R. J. Reynolds; S. L. Tufte; G. J. Madsen; K. P. Jaehnig; J. W. Percival
texts
eye 70
favorite 0
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The Wisconsin H-Alpha Mapper (WHAM) has surveyed the distribution and kinematics of ionized gas in the Galaxy above declination -30 degrees. The WHAM Northern Sky Survey (WHAM-NSS) has an angular resolution of one degree and provides the first absolutely-calibrated, kinematically-resolved map of the H-Alpha emission from the Warm Ionized Medium (WIM) within ~ +/-100 km/s of the Local Standard of Rest. Leveraging WHAM's 12 km/s spectral resolution, we have modeled and removed atmospheric...
Source: http://arxiv.org/abs/astro-ph/0309117v1
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38
Sep 18, 2013
09/13
by
Kathleen A. Barger; Lawrence M. Haffner; Bart P. Wakker; Alex S. Hill; Greg J. Madsen; Allison K. Duncan
texts
eye 38
favorite 0
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The high-velocity cloud (HVC) Complex A is a probe of the physical conditions in the Galactic halo. The kinematics, morphology, distance, and metallicity of Complex A indicate that it represents new material that is accreting onto the Galaxy. We present Wisconsin H-alpha Mapper (WHAM) kinematically resolved observations of Complex A over the velocity range of -250 to -50 km/s in the local standard of rest reference frame. These observations include the first full H-alpha intensity map of...
Source: http://arxiv.org/abs/1211.1973v2
60
60
Sep 17, 2013
09/13
by
Sergei I. Ipatov; Alexander S. Kutyrev; Greg J. Madsen; John C. Mather; S. Harvey Moseley; Ronald J. Reynolds
texts
eye 60
favorite 0
comment 0
The simulated Doppler shifts of the solar Mg I Fraunhofer line produced by scattering on the solar light by asteroidal, cometary, and trans-Neptunian dust particles are compared with the shifts obtained by Wisconsin H-Alpha Mapper (WHAM) spectrometer. The simulated spectra are based on the results of integrations of the orbital evolution of particles. The deviation of the derived spectral parameters for various sources of dust used in the model reached maximum at the elongation (measured...
Source: http://arxiv.org/abs/0711.3494v2
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49
Jul 20, 2013
07/13
by
G. J. Madsen; R. J. Reynolds; S. I. Ipatov; A. S. Kutyrev; J. C. Mather; S. H. Moseley
texts
eye 49
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We report on new observations of the motion of zodiacal dust using optical absorption line spectroscopy of zodiacal light. We have measured the change in the profile shape of the scattered solar Mg I 5184 line toward several lines of sight in the ecliptic plane as well as the ecliptic pole. The variation in line centroid and line width as a function of helio-ecliptic longitude show a clear prograde signature and suggest that significant fraction of the dust follows non-circular orbits that are...
Source: http://arxiv.org/abs/astro-ph/0604229v1
50
50
Sep 20, 2013
09/13
by
S. I. Ipatov; A. S. Kutyrev; G. J. Madsen; J. C. Mather; S. H. Moseley; R. J. Reynolds
texts
eye 50
favorite 0
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We present simulated observations of the Doppler shifts of the solar Mg I Fraunhofer line scattered by asteroidal, cometary, and trans-Neptunian dust particles. The studies are based on the results of integrations of orbital evolution of particles under the gravitational influence of planets, the Poynting-Robertson drag, radiation pressure, and solar wind drag. The derived shifts in the centroid and profile of the line with solar elongation are different for different sources of dust. A...
Source: http://arxiv.org/abs/astro-ph/0608141v1
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39
Sep 19, 2013
09/13
by
A. N. Witt; B. Gold; F. S. Barnes III; C. T. DeRoo; U. P. Vijh; G. J. Madsen
texts
eye 39
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The diffuse high-latitude H-alpha background is widely believed to be predominantly the result of in-situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of the diffuse high-latitude H-alpha intensity in regions dominated by Galactic cirrus dust and much of the variance in the high-latitude H-alpha background are the result of scattering by interstellar dust of H-alpha photons originating elsewhere in the Galaxy....
Source: http://arxiv.org/abs/1010.4361v1
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55
Sep 21, 2013
09/13
by
L. M. Haffner; A. K. Duncan; S. M. Hoffman; G. J. Madsen; A. S. Hill; R. J. Reynolds
texts
eye 55
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H-alpha emission from neutral halo clouds probes the radiation and hydrodynamic conditions in the halo. Armed with such measurements, we can explore how radiation escapes from the Galactic plane and how infalling gas can survive a trip through the halo. The Wisconsin H-Alpha Mapper (WHAM) is one of the most sensitive instruments for detecting and mapping optical emission from the ISM. Here, we present recent results exploring the ionization of two infallling high-velocity complexes. First, we...
Source: http://arxiv.org/abs/0901.0940v1
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68
Sep 20, 2013
09/13
by
L. Deslauriers; P. C. Haljan; P. J. Lee; K-A. Brickman; B. B. Blinov; M. J. Madsen; C. Monroe
texts
eye 68
favorite 0
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We report on ground state laser cooling of single 111Cd+ ions confined in radio-frequency (Paul) traps. Heating rates of trapped ion motion are measured for two different trapping geometries and electrode materials, where no effort was made to shield the electrodes from the atomic Cd source. The low measured heating rates suggest that trapped 111Cd+ ions may be well-suited for experiments involving quantum control of atomic motion, including applications in quantum information science.
Source: http://arxiv.org/abs/quant-ph/0404142v1
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46
Sep 19, 2013
09/13
by
P. J. Lee; B. B. Blinov; K. Brickman; L. Deslauriers; M. J. Madsen; R. Miller; D. L. Moehring; D. Stick; C. Monroe
texts
eye 46
favorite 0
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We report new techniques for driving high-fidelity stimulated Raman transitions in trapped ion qubits. An electro-optic modulator induces sidebands on an optical source, and interference between the sidebands allows coherent Rabi transitions to be efficiently driven between hyperfine ground states separated by 14.53 GHz in a single trapped 111Cd+ ion.
Source: http://arxiv.org/abs/quant-ph/0304188v1
131
131
Sep 17, 2013
09/13
by
S. A. Mao; B. M. Gaensler; M. Haverkorn; E. G. Zweibel; G. J. Madsen; N. M. McClure-Griffiths; A. Shukurov; P. P. Kronberg
texts
eye 131
favorite 0
comment 0
We present a study of the vertical magnetic field of the Milky Way towards the Galactic poles, determined from observations of Faraday rotation toward more than 1000 polarized extragalactic radio sources at Galactic latitudes |b| > 77 degs, using the Westerbork Radio Synthesis Telescope and the Australia Telescope Compact Array. We find median rotation measures (RMs) of 0.0 +/- 0.5 rad/m^2 and +6.3 +/- 0.7 rad/m^2 toward the north and south Galactic poles, respectively, demonstrating that...
Source: http://arxiv.org/abs/1003.4519v1
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53
Sep 21, 2013
09/13
by
L. M. Haffner; R. -J. Dettmar; J. E. Beckman; K. Wood; J. D. Slavin; C. Giammanco; G. J. Madsen; A. Zurita; R. J. Reynolds
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This article reviews observations and models of the diffuse ionized gas that permeates the disk and halo of our Galaxy and others. It was inspired by a series of invited talks presented during an afternoon scientific session of the 65th birthday celebration for Professor Carl Heiles held at Arecibo Observatory in August 2004. This review is in recognition of Carl's long standing interest in and advocacy for studies of the ionized as well as the neutral components of the interstellar medium.
Source: http://arxiv.org/abs/0901.0941v1
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38
Jul 20, 2013
07/13
by
Kenneth Wood; Alex S. Hill; M. Ryan Joung; Mordecai-Mark Mac Low; Robert A. Benjamin; L. Matthew Haffner; R. J. Reynolds; G. J. Madsen
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We investigate models for the photoionization of the widespread diffuse ionized gas in galaxies. In particular we address the long standing question of the penetration of Lyman continuum photons from sources close to the galactic midplane to large heights in the galactic halo. We find that recent hydrodynamical simulations of a supernova-driven interstellar medium have low density paths and voids that allow for ionizing photons from midplane OB stars to reach and ionize gas many kiloparsecs...
Source: http://arxiv.org/abs/1007.5348v1
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73
Sep 18, 2013
09/13
by
D. L. Moehring; B. B. Blinov; D. W. Gidley; R. N. Kohn Jr.; M. J. Madsen; T. D. Sanderson; R. S. Vallery; C. Monroe
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We report precision measurements of the excited state lifetime of the $5p$ $^2P_{1/2}$ and $5p$ $^2P_{3/2}$ levels of a single trapped Cd$^+$ ion. The ion is excited with picosecond laser pulses from a mode-locked laser and the distribution of arrival times of spontaneously emitted photons is recorded. The resulting lifetimes are 3.148 $\pm$ 0.011 ns and 2.647 $\pm$ 0.010 ns for $^2P_{1/2}$ and $^2P_{3/2}$ respectively. With a total uncertainty of under 0.4%, these are among the most precise...
Source: http://arxiv.org/abs/quant-ph/0505111v1
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42
Sep 21, 2013
09/13
by
L. M. Haffner; R. J. Reynolds; G. J. Madsen; A. S. Hill; K. A. Barger; K. P. Jaehnig; E. J. Mierkiewicz; J. W. Percival; N. Chopra
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After a successful eleven-year campaign at Kitt Peak, we moved the Wisconsin H-Alpha Mapper (WHAM) to Cerro Tololo in early 2009. Here we present some of the early data after a few months under southern skies. These maps begin to complete the first all-sky, kinematic survey of the diffuse H-alpha emission from the Milky Way. Much of this emission arises from the Warm Ionized Medium (WIM), a significant component of the ISM that extends a few kiloparsecs above the Galactic disk. While this first...
Source: http://arxiv.org/abs/1008.0612v1
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46
Jul 20, 2013
07/13
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M. v. Zimmermann; T. Frello; N. H. Andersen; J. Madsen; M. Käll; O. Schmidt; T. Niemöller; J. R. Schneider; H. F. Poulsen; Th. Wolf; R. Liang; P. Dosanjh; W. N. Hardy
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High energy x-ray diffraction is used to investigate the bulk oxygen ordering properties of YBa_2Cu_3O_{6+x}. Superstructures of Cu-O chains aligned along the b axis and ordered with periodicity ma, along the a axis have been observed. For $x < 0.62$ the only observed superstructure is ortho-II with m=2. At room temperature we find ortho-III (m=3) for $0.72\le x\le 0.82$, ortho-V (m=5) in a mixed state with ortho-II at x=0.62, and ortho-VIII (m=8) at x=0.67. Ortho-II is a 3D ordered...
Source: http://arxiv.org/abs/cond-mat/9906251v1
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60
Sep 20, 2013
09/13
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L. Deslauriers; M. Acton; B. B. Blinov; K. -A. Brickman; P. C. Haljan; W. K. Hensinger; D. Hucul; S. Katnik; R. N. Kohn, Jr.; P. J. Lee; M. J. Madsen; P. Maunz; S. Olmschenk; D. L. Moehring; D. Stick; J. Sterk; M. Yeo; K. C. Younge; C. Monroe
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Atomic cadmium ions are loaded into radiofrequency ion traps by photoionization of atoms in a cadmium vapor with ultrafast laser pulses. The photoionization is driven through an intermediate atomic resonance with a frequency-quadrupled mode-locked Ti:Sapphire laser that produces pulses of either 100 fsec or 1 psec duration at a central wavelength of 229 nm. The large bandwidth of the pulses photoionizes all velocity classes of the Cd vapor, resulting in high loading efficiencies compared to...
Source: http://arxiv.org/abs/quant-ph/0608043v2
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101
Sep 21, 2013
09/13
by
David A. Thilker; Luciana Bianchi; Gerhardt Meurer; Armando Gil de Paz; Samuel Boissier; Barry F. Madore; Alessandro Boselli; Annette M. N. Ferguson; Juan Carlos Muńoz-Mateos; Greg J. Madsen; Salman Hameed; Roderik A. Overzier; Karl Forster; Peter G. Friedman; D. Christopher Martin; Patrick Morrissey; Susan G. Neff; David Schiminovich; Mark Seibert; Todd Small; Ted K. Wyder; Jose Donas; Timothy M. Heckman; Young-Wook Lee; Bruno Milliard; R. Michael Rich; Alex S. Szalay; Barry Y. Welsh;...
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We have initiated a search for extended ultraviolet disk (XUV-disk) galaxies in the local universe. Herein, we compare GALEX UV and visible--NIR images of 189 nearby (D$
Source: http://arxiv.org/abs/0712.3555v1
