29,533 research outputs found
W Plus Heavy Quark Production at the Tevatron
We summarize the motivations for and the status of the calculation of the heavy quark production process in colliders to Next-to-Leading
Order in QCD. This process can be used to constrain the strange quark
distribution function at high at the Tevatron, and also to study the
bottom content of ~jet events. In addition, when crossed, the calculation
essentially describes the single top quark production process to
Next-to-Leading Order in QCD.Comment: Presented by S. Keller at DPF94 Meeting, Albuquerque, New Mexico,
August 1-6,1994. 4 pages, no macros, no figures. Fermilab-Conf-94/260-T,
FSU--HEP--940817. A postscript file is available via anonymous ftp at
hepsg1.physics.fsu.edu, file is /pub/keller/fsu-hep-940817.p
Solid rocket motor internal insulation
Internal insulation in a solid rocket motor is defined as a layer of heat barrier material placed between the internal surface of the case propellant. The primary purpose is to prevent the case from reaching temperatures that endanger its structural integrity. Secondary functions of the insulation are listed and guidelines for avoiding critical problems in the development of internal insulation for rocket motors are presented
Stellar Associations and their Field East of LMC 4 in the Large Magellanic Cloud
We report about the stellar content and the luminosity and mass functions of
three stellar associations and their field located on the north-east edge of
the super-bubble LMC 4 in the Large Magellanic Cloud.Comment: To be appeared in the meeting Proceedings of ``Modes of Star
Formation and the Origin of Field Populations'', Heidelberg, Germany, October
2000; to be published in the ASP Conference Series, edited by E. K. Grebel
and W. Brandne
Mechanisms of superconductivity investigated by nuclear radiation
Investigation focused on the behavior of superconducting magnet and its constituent materials during and after exposure to nuclear radiation. The results will indicate the feasibility of their use in diverse applications and various environments
Which Way Was I Going? Contextual Retrieval Supports the Disambiguation of Well Learned Overlapping Navigational Routes
Groundbreaking research in animals has demonstrated that the hippocampus contains neurons that distinguish betweenoverlapping navigational trajectories. These hippocampal neurons respond selectively to the context of specific episodes despite interference from overlapping memory representations. The present study used functional magnetic resonanceimaging in humans to examine the role of the hippocampus and related structures when participants need to retrievecontextual information to navigate well learned spatial sequences that share common elements. Participants were trained outside the scanner to navigate through 12 virtual mazes from a ground-level first-person perspective. Six of the 12 mazes shared overlapping components. Overlapping mazes began and ended at distinct locations, but converged in the middle to share some hallways with another maze. Non-overlapping mazes did not share any hallways with any other maze. Successful navigation through the overlapping hallways required the retrieval of contextual information relevant to thecurrent navigational episode. Results revealed greater activation during the successful navigation of the overlapping mazes compared with the non-overlapping mazes in regions typically associated with spatial and episodic memory, including thehippocampus, parahippocampal cortex, and orbitofrontal cortex. When combined with previous research, the current findings suggest that an anatomically integrated system including the hippocampus, parahippocampal cortex, and orbitofrontal cortexis critical for the contextually dependent retrieval of well learned overlapping navigational routes
Oxygen-isotope effect on the superconducting gap in the cuprate superconductor Y_{1-x}Pr_xBa_2Cu_3O_{7-\delta}
The oxygen-isotope (^{16}O/^{18}O) effect (OIE) on the zero-temperature
superconducting energy gap \Delta_0 was studied for a series of
Y_{1-x}Pr_xBa_2Cu_3O_{7-\delta} samples (0.0\leq x\leq0.45). The OIE on
\Delta_0 was found to scale with the one on the superconducting transition
temperature. These experimental results are in quantitative agreement with
predictions from a polaronic model for cuprate high-temperature superconductors
and rule out approaches based on purely electronic mechanisms.Comment: 5 pages, 3 figure
Gemini/GMOS photometry of intermediate-age star clusters in the Large Magellanic Cloud
We present Gemini South GMOS g,i photometry of 14 intermediate-age Large
Magellanic Cloud (LMC) star clusters, namely: NGC 2155, 2161, 2162, 2173, 2203,
2209, 2213, 2231, 2249, Hodge 6, SL 244, 505, 674, and 769, as part of a
continuing project to investigate the extended Main Sequence Turnoff (EMSTO)
phenomenon. Extensive artificial star tests were made over the observed field
of view. These tests reveal the observed behaviour of photometric errors with
magnitude and crowding. The cluster stellar density radial profiles were traced
from star counts over the extent of the observed field. We adopt clus- ter
radii and build colour-magnitude diagrams (CMDs) with cluster features clearly
identified. We used the cluster (g,g-i) CMDs to estimate ages from the matching
of theoretical isochrones. The studied LMC clusters are confirmed to be
intermediate-age clusters, which range in age 9.10 < log(t) < 9.60. NGC 2162
and NGC 2249 look like new EMSTO candidates, in addition to NGC 2209, on the
basis of having dual red clumps.Comment: MNRAS, accepte
Compositeness Test at the FMC with Bhabha Scattering
It is possible that quarks and/or leptons have substructure that will become
manifest at high energies. Here we investigate the limits on the muon
compositeness scale that could be obtained at the First Muon Collider using
Bhabha scattering. We study this limit as a function of the collider energy and
the angular cut imposed by the detector capability.Comment: talk given by S. Keller at the Workshop on Physics at the First Muon
Collider and the Front End of a Muon Collider, Fermilab, November 6--9, 1997,
to appear in the Proceeding
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