A Biased Review of Sociophysics

Various aspects of recent sociophysics research are shortly reviewed: Schelling model as an example for lack of interdisciplinary cooperation, opinion dynamics, combat, and citation statistics as an example for strong interdisciplinarity.Comment: 16 pages for J. Stat. Phys. including 2 figures and numerous reference

Interplay of structural and electronic phase separation in single crystalline La(2)CuO(4.05) studied by neutron and Raman scattering

We report a neutron and Raman scattering study of a single-crystal of La(2)CuO(4.05) prepared by high temperature electrochemical oxidation. Elastic neutron scattering measurements show the presence of two phases, corresponding to the two edges of the first miscibility gap, all the way up to 300 K. An additional oxygen redistribution, driven by electronic energies, is identified at 250 K in Raman scattering (RS) experiments by the simultaneous onset of two-phonon and two-magnon scattering, which are fingerprints of the insulating phase. Elastic neutron scattering measurements show directly an antiferromagnetic ordering below a N\'eel temperature of T_N =210K. The opening of the superconducting gap manifests itself as a redistribution of electronic Raman scattering below the superconducting transition temperature, T_c = 24K. A pronounced temperature-dependent suppression of the intensity of the (100) magnetic Bragg peak has been detected below T_c. We ascribe this phenomenon to a change of relative volume fraction of superconducting and antiferromagnetic phases with decreasing temperature caused by a form of a superconducting proximity effect.Comment: 9 pages, including 9 eps figures, submitted to PR

Treasurehunt: Transients and variability discovered with HST in the JWST North Ecliptic Pole time-domain field

The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a >14' diameter field optimized for multiwavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over three cycles (the "TREASUREHUNT" program), deep images were obtained with the Wide Field Camera on the Advanced Camera for Surveys in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ∼88 arcmin2, with time intervals between individual epochs that range between 1 day and 4+ yr. To a depth of mAB ≃ 29.5 mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable and estimate that ∼80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are active galactic nuclei (AGNs), where we find 0.42% of the general z ≲ 6 field galaxy population to vary at the ∼3σ level. Based on a 5 yr time frame, this translates into a random supernova areal density of up to ∼0.07 transients arcmin−2 (∼245 deg−2) per epoch and a variable AGN areal density of ∼1.25 variables arcmin−2 (∼4500 deg−2) to these depths

THE SANDIA X-RAY LASER PROGRAM

Le laser au rayon X en train d'être développé aux Laboratoires Sandia utilise un rayonnement keV intense, produit par la compression cylindrique ("Z-pinch") d'une bouffée de gaz, pour obtenir les ions de la série isoélectronique F par la photoionisation des ions Ne. Les populations des niveaux de la configuration (2p)5(3p) et de la configuration (2p)5(3s) sont inverties par des processus de recombinaison des ions. Une enveloppe annulaire de stagnation maintient la séparation entre la source du rayonnement et le plasma étant lasé. Une couche mince d'aluminium ou sodium sert pour changer la longueur d'onde du rayonnement. La méthode pour arriver aux dimensions et à la densité du laser au rayon X est décrite.The Sandia X-ray Laser Program is based on the use of intense keV radiation produced by gas puff, Z-pinch implosions to photoionize Ne-like ions to F-like ions. A 3p-3s population inversion is generated via recombination processes. An annular stagnation shell is used to separate the imploding pump source from the lasant. We are also developing a converter technology for examining the Na-Ne line matching scheme. Design considerations and some computational results are presented

Z-PINCH IMPLOSION DRIVEN X-RAY LASER RESEARCH

In experiments performed during the past two years on Proto II (a 10-TW pulsed-power accelerator), we imploded annular plasmas onto thin-walled annular x-ray laser targets in order to create a radiation pump source for x-ray laser physics studies. This Z-pinch must be axially uniform and must efficiently produce the pump radiation without destroying the laser medium on the cylindrical axis of symmetry. To characterize the pump source x-rays and lasant conditions, we regularly field a large number of x-ray diagnostics. In recent experiments, we produced over 15 kJ of ≥1-keV pump radiation with an imploding neon gas-puff load. We are considering both recombination and resonance-pumped x-ray laser schemes