838 research outputs found

    Development of ductile claddings for dispersion-strengthened nickel-base alloys Final report

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    Development of ductile oxidation-resistant cladding alloys for thoria dispersion, strengthened nickel and nickel-chromiu

    Statistical hadronization phenomenology in K/πK/\pi fluctuations at ultra-relativistic energies

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    We discuss the information that can be obtained from an analysis of fluctuations in heavy ion collisions within the context of the statistical model of particle production. We then examine the recently published experimental data on ratio fluctuations, and use it to obtain constraints on the statistical properties (physically relevant ensemble, degree of chemical equilibration, scaling across energies and system sizes) and freeze-out dynamics (amount of reinteraction between chemical and thermal freeze-out) of the system.Comment: Proceedings, SQM2009. Fig. 4, the main results figure, was wrong due to editing mistake, now correcte

    Tracking and imaging gamma ray experiment (TIGRE) for 1 to 100 MEV gamma ray astronomy

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    A large international collaboration from the high energy astrophysics community has proposed the Tracking and Imaging Gamma Ray Experiment (TIGRE) for future space observations. TIGRE will image and perform energy spectroscopy measurements on celestial sources of gamma rays in the energy range from 1 to 100 MeV. This has been a difficult energy range experimentally for gamma ray astronomy but is vital for the future considering the recent exciting measurements below 1 and above 100 MeV. TIGRE is both a double scatter Compton and gamma ray pair telescope with direct imaging of individual gamma ray events. Multi‐layers of Si strip detectors are used as Compton and pair converters CsI(Tl) scintillation detectors are used as a position sensitive calorimeter. Alternatively, thick GE strip detectors may be used for the calorimeter. The Si detectors are able to track electrons and positrons through successive Si layers and measure their directions and energy losses. Compton and pair events are completely reconstructed allowing each event to be imaged on the sky. TIGRE will provide an order‐of‐magnitude improvement in discrete source sensitivity in the 1 to 100 MeV energy range and determine spectra with excellent energy and excellent angular resolutions. It’s wide field‐of‐view of π sr permits observations of the entire sky for extended periods of time over the life of the mission

    On Orbit Performance of the MIPS Instrument

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    The Multiband Imaging Photometer for Spitzer (MIPS) provides long wavelength capability for the mission, in imaging bands at 24, 70, and 160 microns and measurements of spectral energy distributions between 52 and 100 microns at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The Si:As BIB 24 micron array has excellent photometric properties, and measurements with rms relative errors of 1% or better can be obtained. The two longer wavelength arrays use Ge:Ga detectors with poor photometric stability. However, the use of 1.) a scan mirror to modulate the signals rapidly on these arrays, 2.) a system of on-board stimulators used for a relative calibration approximately every two minutes, and 3.) specialized reduction software result in good photometry with these arrays also, with rms relative errors of less than 10%

    The Burst and Transient Source Experiment (BATSE) Earth Occultation Catalog of Low-Energy Gamma-Ray Sources

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    The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the low-energy gamma-ray sky (20-1000 keV) between 1991 April and 2000 May (9.1y). Using the Earth Occultation Technique to extract flux information, a catalog of sources using data from the BATSE large area detectors has been prepared. The first part of the catalog consists of results from the monitoring of 58 sources, mostly Galactic. For these sources, we have included tables of flux and spectral data, and outburst times for transients. Light curves (or flux histories) have been placed on the world wide web. We then performed a deep-sampling of 179 objects (including the aforementioned 58 objects) combining data from the entire 9.1y BATSE dataset. Source types considered were primarily accreting binaries, but a small number of representative active galaxies, X-ray-emitting stars, and supernova remnants were also included. The deep sample results include definite detections of 83 objects and possible detections of 36 additional objects. The definite detections spanned three classes of sources: accreting black hole and neutron star binaries, active galaxies and supernova remnants. Flux data for the deep sample are presented in four energy bands: 20-40, 40-70, 70-160, and 160-430 keV. The limiting average flux level (9.1 y) for the sample varies from 3.5 to 20 mCrab (5 sigma) between 20 and 430 keV, depending on systematic error, which in turn is primarily dependent on the sky location. To strengthen the credibility of detection of weaker sources (5-25 mCrab), we generated Earth occultation images, searched for periodic behavior using FFT and epoch folding methods, and critically evaluated the energy-dependent emission in the four flux bands.Comment: 64 pages, 17 figures, abstract abridged, Accepted by ApJ

    Resonances and fluctuations of strange particle in 200 GeV Au-Au collisions

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    We perform an analysis of preliminary data on strange particles yields and fluctuations within the Statistical hadronization model. We begin by describing the theoretical disagreements between different statistical models currently on the market. We then show how the simultaneous analysis of yields and fluctuations can be used to differentiate between the different models, and determine if one of them can be connected to underlying physics. We perform a study on a RHIC 200 GeV data sample that includes stable particles, resonances, and the event-by-event fluctuation of the K/πK/\pi ratio. We show that the equilibrium statistical model can not describe the fluctuation, unless an unrealistically small volume is assumed. Such small volume then makes it impossible to describe the total particle multiplicity. The non-equilibrium model,on the other hand, describes both the K/πK/\pi fluctuation and yields acceptably due to the extra boost to the π\pi fluctuation provided by the high pion chemical potential. Λ(1520)\Lambda(1520) and K∗K^* abundance is described within error bars, but the Σ∗\Sigma^* is under-predicted to ∌\sim 1.5 standard deviations. We suggest further measurements that have the potential to test the non-equilibrium model, as well as gauge the effect of re-interactions between hadronization and freeze-out.Comment: References added, equations corrected. As accepted for publication by Journal of Physics

    Magazine and reader constructions of 'metrosexuality' and masculinity: a membership categorisation analysis

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    Since the launch of men's lifestyle magazines in the 1980s, academic literature has predominantly focused on them as a cultural phenomenon arising from entrepreneurial and commercial initiatives and/or as cultural texts that proffer representations of masculinity such as 'new lad' and 'new dad'. This paper steps aside from the focus on culture and, instead, treats magazine content as a discursive space in which gender and sexuality are oriented to, negotiated, and accomplished within and beyond the magazine itself (i.e. through readers' responses). Specifically, membership categorisation analysis is deployed to explore how the relatively new (and perhaps alternative) category for men - 'metrosexual' - is presented and received. Our analysis suggests that masculinity concerns are central in debates about 'metrosexuality', with self-identified 'metrosexuals' invoking heterosexual prowess and self-respect on the one hand, and critics (e.g. selfidentified 'real men') lamenting 'metrosexuality' for its perceived effeminacy and lack of authenticity on the other. Implications for understanding contemporary masculinities are discussed
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