81 research outputs found
Dark sectors 2016 Workshop: community report
This report, based on the Dark Sectors workshop at SLAC in April 2016,
summarizes the scientific importance of searches for dark sector dark matter
and forces at masses beneath the weak-scale, the status of this broad
international field, the important milestones motivating future exploration,
and promising experimental opportunities to reach these milestones over the
next 5-10 years
Adding the s-Process Element Cerium to the APOGEE Survey: Identification and Characterization of Ce II Lines in the H-band Spectral Window
Nine Ce ii lines have been identified and characterized within the spectral window observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey (between λ1.51 and 1.69 μm). At solar metallicities, cerium is an element that is produced predominantly as a result of the slow capture of neutrons (the s-process) during asymptotic giant branch stellar evolution. The Ce ii lines were identified using a combination of a high-resolution () Fourier Transform Spectrometer (FTS) spectrum of α Boo and an APOGEE spectrum (R = 22,400) of a metal-poor, but s-process enriched, red giant (2M16011638-1201525). Laboratory oscillator strengths are not available for these lines. Astrophysical gf-values were derived using α Boo as a standard star, with the absolute cerium abundance in α Boo set by using optical Ce ii lines that have precise published laboratory gf-values. The near-infrared Ce ii lines identified here are also analyzed, as consistency checks, in a small number of bright red giants using archival FTS spectra, as well as a small sample of APOGEE red giants, including two members of the open cluster NGC 6819, two field stars, and seven metal-poor N- and Al-rich stars. The conclusion is that this set of Ce ii lines can be detected and analyzed in a large fraction of the APOGEE red giant sample and will be useful for probing chemical evolution of the s-process products in various populations of the Milky Way
Measurement of -meson production in CuAu at GeV and UU at GeV
The PHENIX experiment reports systematic measurements at the Relativistic
Heavy Ion Collider of -meson production in asymmetric CuAu collisions
at =200 GeV and in UU collisions at =193
GeV. Measurements were performed via the decay
channel at midrapidity . Features of -meson production
measured in CuCu, CuAu, AuAu, and UU collisions were found to not
depend on the collision geometry, which was expected because the yields are
averaged over the azimuthal angle and follow the expected scaling with
nuclear-overlap size. The elliptic flow of the meson in CuAu,
AuAu, and UU collisions scales with second order participant eccentricity
and the length scale of the nuclear overlap region (estimated with the number
of participating nucleons). At moderate , -meson production measured
in CuAu and UU collisions is consistent with coalescence-model
predictions, whereas at high the production is in agreement with
expectations for in-medium energy loss of parent partons prior to their
fragmentation. The elliptic flow for mesons measured in CuAu and
UU collisions is well described by a (2+1)D viscous-hydrodynamic model with
specific-shear viscosity .Comment: 411 authors from 76 institutions, 16 pages, 12 figures, 9 tables,
2012 data. v1 is version submitted to Physical Review C. Plain text data
tables for the points plotted in figures for this and previous PHENIX
publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Hydrothermal Conditions and the Origin of Cellular Life
The conditions and properties of hydrothermal vents and hydrothermal fields are compared in terms of their ability to support processes related to the origin of life. The two sites can be considered as alternative hypotheses, and from this comparison we propose a series of experimental tests to distinguish between them, focusing on those that involve concentration of solutes, self-assembly of membranous compartments, and synthesis of polymers. Key Word: Hydrothermal systems
The Canonization of Warner Brothers Cartoons, or How Bugs Bunny Came to the Museum of Modern Art
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