Library of medium-resolution fiber optic echelle spectra of F, G, K, and M field dwarfs to giants stars

We present a library of Penn State Fiber Optic Echelle (FOE) observations of a sample of field stars with spectral types F to M and luminosity classes V to I. The spectral coverage is from 3800 AA to 10000 AA with nominal a resolving power 12000. These spectra include many of the spectral lines most widely used as optical and near-infrared indicators of chromospheric activity such as the Balmer lines (H_alpha, H_beta), Ca II H & K, Mg I b triplet, Na I D_{1} and D_{2}, He I D_{3}, and Ca II IRT lines. There are also a large number of photospheric lines, which can also be affected by chromospheric activity, and temperature sensitive photospheric features such as TiO bands. The spectra have been compiled with the goal of providing a set of standards observed at medium resolution. We have extensively used such data for the study of active chromosphere stars by applying a spectral subtraction technique. However, the data set presented here can also be utilized in a wide variety of ways ranging from radial velocity templates to study of variable stars and stellar population synthesis. This library can also be used for spectral classification purposes and determination of atmospheric parameters (T_eff, log{g}, [Fe/H]). A digital version of all the fully reduced spectra is available via ftp and the World Wide Web (WWW) in FITS format.Comment: Latex file with 17 pages, 4 figures. Full postscript (text and figures) available at http://www.ucm.es/info/Astrof/fgkmsl/FOEfgkmsl.html To be published in ApJ

A study of breakdown limits in microstrip gas counters with preamplification structures

We have studied the charge and breakdown limits of Microstrip Gas Counters (MSGC's) with two different preamplification structures: the Gas Electron Multiplier (GEM) and the Parallel-Plate Avalanche Counter (PPAC). It was found that in both cases the breakdown limit was increased by 1-2 orders of magnitude compared to the bare MSGC and that this was due to the spreading of the primary electron cloud during pre-amplification. This spreading reduces the charge density in the final MSGC avalanche, permitting much higher total gains before streamers form. The real practical gain limitations in these two-stage detectors arose not from sparking, but from a loss of proportionality due to space charge effects.http://www.sciencedirect.com/science/article/B6TJM-3V8TV5X-34/1/126083510ba3bfd528bad96ccdbc08a

Global Analysis of Nucleon Strange Form Factors at Low Q2Q^2

We perform a global analysis of all recent experimental data from elastic parity-violating electron scattering at low $Q^2$. The values of the electric and magnetic strange form factors of the nucleon are determined at $Q^2 = 0.1$ GeV/$c^2$ to be $G^s_E = -0.008 \pm 0.016$ and $G^s_M = 0.29 \pm 0.21$.Comment: 8 pages, 1 figur

On formal verification of arithmetic-based cryptographic primitives

Cryptographic primitives are fundamental for information security: they are used as basic components for cryptographic protocols or public-key cryptosystems. In many cases, their security proofs consist in showing that they are reducible to computationally hard problems. Those reductions can be subtle and tedious, and thus not easily checkable. On top of the proof assistant Coq, we had implemented in previous work a toolbox for writing and checking game-based security proofs of cryptographic primitives. In this paper we describe its extension with number-theoretic capabilities so that it is now possible to write and check arithmetic-based cryptographic primitives in our toolbox. We illustrate our work by machine checking the game-based proofs of unpredictability of the pseudo-random bit generator of Blum, Blum and Shub, and semantic security of the public-key cryptographic scheme of Goldwasser and Micali.Comment: 13 page

Instrumentation for X-Ray Astronomy from High-Altitude Balloons: Recent Developments and Future Plans

We describe our current effort and future plans to develop new detectors and methods for studying hard x-ray emission from the Universe during balloon flights

Gauge Fields Out-Of-Equilibrium: A Gauge Invariant Formulation and the Coulomb Gauge

We study the abelian Higgs model out-of-equilibrium in two different approaches, a gauge invariant formulation, proposed by Boyanovsky et al. \cite{Boyanovsky:1996dc} and in the Coulomb gauge. We show that both approaches become equivalent in a consistent one loop approximation. Furthermore, we carry out a proper renormalization for the model in order to prepare the equations for a numerical implementation. The additional degrees of freedom, which arise in gauge theories, influence the behavior of the system dramatically. A comparison with results in the 't Hooft-Feynman background gauge found by us recently, shows very good agreement.Comment: 32 pages, 8 figure

Fast Ground State Manipulation of Neutral Atoms in Microscopic Optical Traps

We demonstrate Rabi flopping at MHz rates between ground hyperfine states of neutral $^{87}$Rb atoms that are trapped in two micron sized optical traps. Using tightly focused laser beams we demonstrate high fidelity, site specific Rabi rotations with crosstalk on neighboring sites separated by $8 \mu\rm m$ at the level of $10^{-3}$. Ramsey spectroscopy is used to measure a dephasing time of $870 \mu\rm s$ which is $\approx$ 5000 times longer than the time for a $\pi/2$ pulse.Comment: 4 pages, 4 figure