25490185
Device Modeling of Superconductor Transition-Edge Sensors Based on the Two-Fluid Theory
In order to support the design and research of sophisticated large-scale transition-edge sensor (TES) circuits, we use basic SPICE elements to develop device models for TESs based on the superfluid-normal fluid theory. In contrast to previous studies, our device model is not limited to small-signal simulation, and it relies only on device parameters that have clear physical meaning and can be easily measured. We integrate the device models in design kits based on powerful electronic design automation tools such as CADENCE and OrCAD and use them for versatile simulations of TES circuits. Comparing our simulation results with published experimental data, we find good agreement which suggests that device models based on the two-fluid theory can be used to predict the behavior of TES circuits reliably. Hence, they are valuable for assisting the design of sophisticated TES circuits.
14896531
Strong Ca II Absorption Lines in the Reddened Quasar SDSS J2339–0912: Evidence of the Collision/Merger in the Host Galaxy?
We report the detection of strong Ca II/Mg II absorption lines at the quasar redshift in the narrow-line quasar SDSS J2339-0912 (z = 0.6604). The quasar exhibits strong Fe II, a small Balmer emission line width, and a very red B - Ks color. Both the optical continuum and broad emission lines are reddened by SMC-like dust of E(B - V) 1.0 mag, while its near-infrared color (J - Ks = 1.60) shows little reddening. The Ca II absorption lines are saturated and resolved with an FWHM of 362 km s-1 and an equivalent width of W = 4.2 A (in the source rest frame). Mg II absorption lines are also saturated and have a similar line width. The line profile and the fact that there is no evidence of starlight from the host galaxy suggest that these absorption lines are not of a stellar origin. The ratio of column density of Ca II to that of dust is consistent with that of the interstellar medium (ISM) in our Galaxy. We suggest that both the heavy reddening and the large absorption line width are due to the highly disturbed ISM on the line of sight toward the quasar and that the disturbance is caused by a galaxy collision or even merger in the quasar host galaxy.
17235519
The Correlation Between X-ray and UV Properties of BAL QSOs
We compile a large sample of broad absorption line (BAL) quasars with X-ray observations from the XMM-Newton archive data and Sloan Digital Sky Survey Data Release 5. The sample consists of 41 BAL QSOs. Among 26 BAL quasars detected in X-ray, spectral analysis is possible for 12 objects. X-ray absorption is detected in all of them. Complementary to that of Gallagher et?al., our sample spans wide ranges of both BALnicity index (BI) and maximum outflow velocity (v max). Combining our sample with that of Gallagher et?al., we find very significant correlations between the intrinsic X-ray weakness and both BI and the maximum velocity of the absorption trough. We do not confirm the previously claimed correlation between absorption column density and BAL parameters. Our tentative interpretation is that X-ray absorption is necessary to the production of the BAL outflow, but the properties of the outflow are largely determined by intrinsic spectral energy distribution of the quasars.
13062064
Polar outflows in six broad absorption line quasars
Using radio observations by FIRST and NVSS, we build a sample of 151 radio-variable quasars selected from the Sloan Digital Sky Survey Data Release 3 (SDSS DR3). Six (and probably another two) of these objects are classified as broad absorption line (BAL) quasars and show radio flux variations of a few tens of percent within 1.5-5 yr. Such large amplitudes of variations imply brightness temperatures much higher than the inverse Compton limits (10(12) K) in all these BAL quasars, suggesting the presence of relativistic jets beaming toward the observer. The angles between the outflow and the jet are constrained to be less than similar to 20 degrees. Such BAL quasars with polar outflows are beyond the simple unification models of BAL and non-BAL quasars, which hypothesize BAL quasars as otherwise normal quasars seen nearly edge-on.
16103411
Partially obscured quasars in the Sloan Digital Sky Survey Early Data Release
We have compiled a sample of 21 low redshift (z . 0.3), luminous active galactic nuclei (AGN) with large Balmer decrements (Hα/Hβ > 7) using the galaxy and QSO catalogs of the Sloan Digital Sky Survey Early Data Release. Using this sample we attempt to determine the fraction of quasars with large internal absorption. We find that these AGN have Strong [O III] λ5007 and broad Hα emission, and that starlight dominates the spectra in the blue band, suggesting that these objects are heavily reddened. Their narrow emission line ratios are similar to those of Seyfert 2 galaxies, yet the average [O III] λ5007 emission is ∼10 times more luminous. Applying the empirical relation between the optical continuum and the Balmer line luminosity for blue quasars, we find that the intrinsic luminosities of these 21 objects are in the range for quasars. We propose that they are obscured, intermediate type quasars analogous to type 1.8 and 1.9 Seyfert galaxies. The ratio of these optically selected, intermediate type quasars to type 1 quasars are found to be around 1, similar to that for local Seyfert galaxies. Preliminary study indicates that most of these quasars are hosted in early type galaxies. Subject headings: galaxies: active — quasars: general — galaxies: nuclei
17240914
XMM observations of BAL Quasars with polar outflows
We have selected a sample of broad absorption line (BAL) quasars which show significant radio variations, indicating the presence of polar BAL outflows. We obtained snapshot XMM observations of four polar BAL QSOs, to check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exist in polar outflows. Two of the sources are detected in X-ray. Spectral fittings show that they are X-ray normal with no intrinsic X-ray absorption, suggesting the X-ray shielding gas might be absent in polar BAL outflows. Comparing to non-BAL QSOs, one of two X-ray nondetected sources remains consistent with X-ray normal, while the other one, which is an iron low-ionization BAL (FeLoBAL), shows an X-ray weakness factor of > 19, suggesting strong intrinsic X-ray absorption. Alternative explanations to the nondetection of strong X-ray absorption in the two X-ray detected sources are 1) the absorption is more complex than a simple neutral absorber, such as partial covering absorption or ionized absorption; 2) there might be significant jet contribution to the detected X-ray emission. Current data is insufficient to test these possibilities, and further observations are required to understand the X-ray nature of polar BAL outflows. Subject headings: quasars: general — quasars: absorption lines — radiation: radio continuum
215597188
Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton–proton collision data
Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton–proton collision data collected in 2011 at $$\sqrt{s}= 7$$s=7 TeV and corresponding to an integrated luminosity of 4.7 fb$$^{-1}$$-1. Tag-and-probe methods using events with leptonic decays of $$W$$W and $$Z$$Z bosons and $$J/\psi $$J/ψ mesons are employed to benchmark these performance parameters. The combination of all measurements results in identification efficiencies determined with an accuracy at the few per mil level for electron transverse energy greater than 30 GeV.
18821053
Comparisons Of Equivalent Circuit Predictions With Measurements For Short Stacks Of RDDS1 Discs, And Their Potential Application To Improved Wakefield Prediction
In fabricating the first X-Band RDDS (Rounded Damped Detuned Structure) accelerator structure, microwave measurements are made on short groups of discs prior to bonding the discs of the entire structure. The design dispersion curves are compared with the frequency measurements. The theory utilized is based on a circuit model adapted to a short stack of slowly varying non-uniform discs. The model reveals the nature of the modes in the structure and may also be used to refit the experimental data to the parameters in a model of the wakefield given earlier [1]. This method allows a more faithful determination of the wakefield that a beam will experience as it traverses the structure. Results obtained on the frequencies are compared to the original design.
14269254
SLC injector simulation and tuning for high charge transport
We have simulated the SLC injector from the thermionic gun through the first accelerating section and used the resulting parameters to tune the injector for optimum performance and high charge transport. Simulations are conducted using PARMELA, a three-dimensional ray-trace code with a two-dimensional space-charge model. The magnetic field profile due to the existing magnetic optics is calculated using POISSON, while SUPERFISH is used to calculate the space harmonics of the various bunchers and the accelerator cavities. The initial beam conditions in the PARMELA code are derived from the EGUN model of the gun. The resulting injector parameters from the PARMELA simulation are used to prescribe experimental settings of the injector components. The experimental results are in agreement with the results of the integrated injector model.
118438022
On the eccentricity distribution of short-period single-planet systems
We apply standard Markov chain Monte Carlo (MCMC) analysis techniques to 50 short-period, single-planet systems discovered with radial velocity technique. We develop a new method for accessing the significance of a non-zero orbital eccentricity, namelyanalysis, which combines the frequentist bootstrap approach with Bayesian analysis of each simulated data set. We find that the eccentricity estimations from theanalysis are generally consistent with the results from both the standard MCMC analysis and previous references. Themethod is particular useful for assessing the significance of small eccentricities. Our results suggest that the current sample size is insufficient to draw robust conclusions about the roles of tidal interaction and perturbations in shaping the eccentricity distribution of short-period single- planet systems. We use a Bayesian population analysis to show that a mixture of analytical distributions is a good approximation of the underlying eccentricity distribution. For short- period planets, we find the most probable values of parameters in the analytical functions given the observed eccentricities. These analytical functions can be used in theoretical investigations or as priors for the eccentricity distribution when analysing short-period planets. As the measurement precision improves and sample size increases, the method can be applied to more complex parametrizations for the underlying distribution of eccentricity for extrasolar planetary systems.
122925118
Monte Carlo simulation of the response of Si(Li) detectors to monoenergetic X-rays
Abstract We present a Monte Carlo simulation of X-ray interaction with a Si(Li) detector which includes for the first time both a detailed description of the atomic excitation and de-excitation and also a physically realistic model of the frontal region of incomplete charge collection. Simulated lineshapes are in good agreement with those measured by us using monoenergetic X-rays of energy 1–10 keV and by varying the two parameters of the model we can generate lineshapes very similar to those reported in the literature for other Si(Li) detectors.