Science with Micro-X: the TES Microcalorimeter X-ray Imaging Rocket

Micro-X is a proposed sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. We describe the payload and the science targeted by this mission including the discussion of three possible Micro-X targets: the Puppis A supernova remnant, the Virgo Cluster, and Circinus X-1. For example, a Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plasma diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. For clusters of galaxies, Micro-X can uniquely study turbulence and the temperature distribution function. For binaries, Micro-X's high resolution spectra will separate the different processes contributing to the Fe K lines at 6 keV and give a clear view of the geometry of the gas flows and circumstellar gas

Partial Deconfinement at Strong Coupling on the Lattice

We provide evidence for partial deconfinement — the deconfinement of a SU(M) subgroup of the SU(N) gauge group — by using lattice Monte Carlo simulations. We take matrix models as concrete examples. By appropriately fixing the gauge, we observe that the M × M submatrices deconfine. This gives direct evidence for partial deconfinement at strong coupling. We discuss the applications to QCD and holography

Direct measurement of two-electron contributions to the ground state energy of heliumlike high-Z ions

We report on a novel technique which exploits Radiative Recombination transitions for a direct experimental determination of the two-electron contributions to the ground state energy in heliumlike high-Z ions. Results are presented of a first experiment which was conducted at an electron beam ion trap for various elements ranging from Z=32 to 83. The comparison with theoretical predictions demonstrates that the achieved precision already provides a sensitive test of second order manybody contributions and approaches the size of the two-electron (screened) Lamb shift. The ptoential of the new technique will be outlined and the capability of the ESR storage ring for future investigations will be emphasized. (orig.)17 refs.Available from TIB Hannover: RO 801(95-55) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A comparative modeling of Supernova 1993J

The light curve of Supernova (SN) 1993J is calculated using two approaches to radiation transport as exemplified by the two computer codes, STELLA and EDDINGTON. Particular attention is paid to shock breakout and the photometry in the U, B, and V bands during the first 120 days. The hydrodynamical model, the explosion of a 13 M_sun star which had lost most of its hydrogenic envelope to a companion, is the same in each calculation. The comparison elucidates differences between the approaches and also serves to validate the results of both. STELLA includes implicit hydrodynamics and is able to model supernova evolution at early times, before the expansion is homologous. STELLA also employs multi-group photonics and is able to follow the radiation as it decouples from the matter. EDDINGTON uses a different algorithm for integrating the transport equation, assumes homologous expansion, and uses a finer frequency resolution. Good agreement is achieved between the two codes only when compatible physical assumptions are made about the opacity. In particular the line opacity near the principal (second) peak of the light curve must be treated primarily as absorptive even though the electron density is too small for collisional deexcitation to be a dominant photon destruction mechanism. Justification is given for this assumption and involves the degradation of photon energy by 'line splitting', i.e. fluorescence. The fact that absorption versus scattering matters to the light curve is indicative of the fact that departures from equilibrium radiative diffusion are important. A new result for SN 1993J is a prediction of the continuum spectrum near the shock breakout (calculated by STELLA) which is superior to the results of other standard single energy group hydrocodes such as VISPHOT or TITAN. Based on the results of our independent codes, we discuss the uncertainties involved in the current time dependent models of supernova light curves. (orig.)Available from TIB Hannover: RR 4697(1049) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Radiochemical search for neutron-rich isotopes of nielsbohrium in the "1"6O + "2"5"4Es reaction

We have used on-line gas chromatography to search for new isotopes of element 107 near the deformed sub-shell at N = 162 and Z = 108. Enhanced nuclear stability is predicted for this region. "2"5"4"gEs was irradiated with "1"6O at barrier energies to minimize the fusion hindrance in the entrance channel and to reduce the excitation energy of the compound nucleus to a minimum value. For half-lives between roughly two seconds and two minutes no signal for a positive identification of a new isotope of element 107 was detected. Consequently, only an upper cross-section limit of a few nanobarns was obtained. While this cross-section limit was too high to probe the influence of the predicted enhanced nuclear ground-state stability on the survival probability in the fission/evaporation competition, a very large cross-section enhancement would have been detectable. (orig.)Available from TIB Hannover: RO 801(94-60) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman