15 KJ FLASH LAMP, POWER CONDITIONING UNIT DESIGNED FOR SAFTY, RELIABILITY & MANUFACTURABILITY*

A 15kJoule, Flash Lamp Power Conditioning Unit has been successfully designed, developed, and deployed in the National Ignition Facility (NIF) Preamplifier Modules (PAM). The primary design philosophy of this power conditioning unit (PCU) is safety, reliability, and manufacturability. Cost reduction over commercially equivalent systems was also achieved through an easily manufactured packaging design optimized to meet NIF requirements. While still maintaining low cost, the PCU design includes a robust control system, fault diagnostic system, and safety features. The pulsed power design includes 6 PFN modules, each including a dual series injection trigger transformer, that drive a total of 12 flash lamp loads. The lamps are individually triggered via a 20kV pulse produced by a 1kV, MCT switched capacitive discharge unit on the primary side of the trigger transformer. The remote control interface includes an embedded controller that captures flash lamp current wave forms and fault status for each shot. The embedded controller provides the flexibility of remotely adjusting both the main drive voltage from 1.6 to 2.5 kV and the trigger voltage from 0 to 20 kV

A General Formula for Black Hole Gravitational Wave Kicks

Although the gravitational wave kick velocity in the orbital plane of coalescing black holes has been understood for some time, apparently conflicting formulae have been proposed for the dominant out-of-plane kick, each a good fit to different data sets. This is important to resolve because it is only the out-of-plane kicks that can reach more than 500 km/s and can thus eject merged remnants from galaxies. Using a different ansatz for the out-of-plane kick, we show that we can fit almost all existing data to better than 5 %. This is good enough for any astrophysical calculation, and shows that the previous apparent conflict was only because the two data sets explored different aspects of the kick parameter space.Comment: 14 pages

The M 31 double nucleus probed with OASIS and HST. A natural m=1 mode?

We present observations with the adaptive optics assisted integral field spectrograph OASIS of the M 31 double nucleus at a spatial resolution better than 0.5 arcsec FWHM. These data are used to derive the two-dimensional stellar kinematics within the central 2 arcsec. Archival WFPC2/HST images are revisited to perform a photometric decomposition of the nuclear region. We also present STIS/HST kinematics obtained from the archive. The luminosity distribution of the central region is well separated into the respective contributions of the bulge, the nucleus including P1 and P2, and the so-called UV peak. We then show that the axis joining P1 and P2, the two local surface brightness maxima, does not coincide with the kinematic major-axis, which is also the major-axis of the nuclear isophotes (excluding P1). We also confirm that the velocity dispersion peak is offset by ~ 0.2 arcsec from the UV peak, assumed to mark the location of the supermassive black hole. The newly reduced STIS/HST velocity and dispersion profiles are then compared to OASIS and other published kinematics. We find significant offsets with previously published data. Simple parametric models are then built to successfully reconcile all the available kinematics. We finally interpret the observations using new N-body simulations. The nearly keplerian nuclear disk of M31 is subject to a natural m=1 mode, with a very slow pattern speed (3 km/s/pc for M_BH = 7 10^7~\Msun), that can be maintained during more than a thousand dynamical times. The resulting morphology and kinematics of the mode can reproduce the M~31 nuclear-disk photometry and mean stellar velocity, including the observed asymmetries. It requires a central mass concentration and a cold disk system representing between 20 and 40% of its mass. Abridged..Comment: 21 pages. accepted for publication in A&

Dynamics of the Globular Cluster System Associated with M87 (NGC 4486). II. Analysis

We present a dynamical analysis of the globular cluster system associated with M87 (= NGC 4486), the cD galaxy near the dynamical center of the Virgo cluster. The analysis utilizes a new spectroscopic and photometric database which is described in a companion paper (Hanes et al. 2001). Using a sample of 278 globular clusters with measured radial velocities and metallicities, and new surface density profiles based on wide-field Washington photometry, we study the dynamics of the M87 globular cluster system both globally --- for the entire cluster sample --- and separately --- for the metal-rich and metal-poor globular cluster samples. This constitutes the largest sample of radial velocities for pure Population II tracers yet assembled for any galaxy. We discuss the implications of our findings for models for the formation of giant elliptical galaxies, globular cluster systems, and the Virgo cluster. (ABRIDGED)Comment: 28 pages, 19 postscript figures, 1 jpeg image. See http://www.physics.rutgers.edu/ast/ast-rap.html to download the manuscript with higher quality figures. Accepted for publication in the Astrophysical Journa

WFPC2 Observations of Compact Star Cluster Nuclei in Low Luminosity Spiral Galaxies

We have used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to image the compact star cluster nuclei of the nearby, late-type, low-luminosity spiral galaxies NGC 4395, NGC 4242, and ESO 359-029. We also analyze archival WFPC2 observations of the compact star cluster nucleus of M33. A comparative analysis of the structural and photometric properties of these four nuclei is presented. All of the nuclei are very compact, with luminosity densities increasing at small radii to the resolution limit of our data. NGC 4395 contains a Seyfert 1 nucleus with a distinct bipolar structure and bright associated filaments which are likely due to [OIII] emission. The M33 nucleus has a complex structure, with elongated isophotes and possible signatures of weak activity, including a jet-like component. The other two nuclei are not known to be active, but share similar physical size scales and luminosities to the M33 and NGC 4395 nuclei. The circumnuclear environments of all four of our program galaxies are extremely diffuse, have only low-to-moderate star formation, and appear to be devoid of large quantities of dust. The central gravitational potentials of the galaxies are also quite shallow, making the origin of these types of `naked' nuclei problematic.Comment: to appear in the July 1999 Astronomical Journal; 38 pages (Latex), 5 tables (postscript), 21 figures (gif); postscript versions of the figures may be obtained via anonymous ftp at ftp://ftp.cv.nrao.edu/NRAO-staff/lmatthew/lanl-nucle

Model comparisons for estimating carbon emissions from North American wildland fire

Research activities focused on estimating the direct emissions of carbon from wildland fires across North America are reviewed as part of the North American Carbon Program disturbance synthesis. A comparison of methods to estimate the loss of carbon from the terrestrial biosphere to the atmosphere from wildland fires is presented. Published studies on emissions from recent and historic time periods and five specific cases are summarized, and new emissions estimates are made using contemporary methods for a set of specific fire events. Results from as many as six terrestrial models are compared. We find that methods generally produce similar results within each case, but estimates vary based on site location, vegetation (fuel) type, and fire weather. Area normalized emissions range from 0.23 kg C m−2 for shrubland sites in southern California/NW Mexico to as high as 6.0 kg C m−2 in northern conifer forests. Total emissions range from 0.23 to 1.6 Tg C for a set of 2003 fires in chaparral-dominated landscapes of California to 3.9 to 6.2 Tg C in the dense conifer forests of western Oregon. While the results from models do not always agree, variations can be attributed to differences in model assumptions and methods, including the treatment of canopy consumption and methods to account for changes in fuel moisture, one of the main drivers of variability in fire emissions. From our review and synthesis, we identify key uncertainties and areas of improvement for understanding the magnitude and spatial-temporal patterns of pyrogenic carbon emissions across North America

Bose-Einstein Correlations of Three Charged Pions in Hadronic Z^0 Decays

Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 10^6 hadronic Z^0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r_3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of \lambda_3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the \lambda_3 value by \~9% and to reduce r_3 by ~6%. The measured \lambda_3 corresponds to a value of 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.Comment: 19 pages, LaTeX, 5 eps figures included, accepted by Eur. Phys. J.

Search for Top Squark Pair Production in the Dielectron Channel

This report describes the first search for top squark pair production in the channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using 74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence level upper limit on sigma*B is presented. The limit is above the theoretical expectation for sigma*B for this process, but does show the sensitivity of the current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report

The Azimuthal Decorrelation of Jets Widely Separated in Rapidity

This study reports the first measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units. The data were accumulated using the D{\O}detector during the 1992--1993 collider run of the Fermilab Tevatron at $\sqrt{s}=$ 1.8 TeV. These results are compared to next--to--leading order (NLO) QCD predictions and to two leading--log approximations (LLA) where the leading--log terms are resummed to all orders in $\alpha_{\scriptscriptstyle S}$. The final state jets as predicted by NLO QCD show less azimuthal decorrelation than the data. The parton showering LLA Monte Carlo {\small HERWIG} describes the data well; an analytical LLA prediction based on BFKL resummation shows more decorrelation than the data.Comment: 6 pages with 4 figures, all uuencoded and gzippe