750 research outputs found

    Heavy Quark Production at HERA

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    Heavy flavour production is one of the key components of the HERA II physics programme. While most of the results presented use leptons or the reconstruction of charmed mesons to identify heavy flavour production, both the H1 and ZEUS experiments now have working microvertex detectors that are being used more and more. In this talk I will summarise a selection of the recent results obtained by the two collaborations.Comment: 10 pages, 18 figures, to appear in the Proceedings of the 8th International Conference on Hyperons, Charm and Beauty Hadrons (BEACH2008), 22-28 June 2008, University of South Carolina, Columbi

    Green's function based unparameterised multi-dimensional kernel density and likelihood ratio estimator

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    This paper introduces a probability density estimator based on Green's function identities. A density model is constructed under the sole assumption that the probability density is differentiable. The method is implemented as a binary likelihood estimator for classification purposes, so issues such as mis-modeling and overtraining are also discussed. The identity behind the density estimator can be interpreted as a real-valued, non-scalar kernel method which is able to reconstruct differentiable density functions.Comment: 7 pages, 4 figures. JPCS accepted it as a proceedings to the ACAT worksho

    The Effects Of Different Amino Acid Concentrations, With Or Without Chromium Supplementation, On The Performance And Yield Of Commercial Broiler Chickens Fed Two Different Feeding Programs.

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    Abstract The objective of this study was to evaluate performance parameters and meat yield of commercial broiler chickens fed diets with different amino acid concentrations, with or without chromium supplementation, and delivered through two different feeding programs over 54 days. The experimental study was completed as a randomized-block design with 4,800, Ross 708 X Ross 708 commercial broiler chickens, picked at random, and evenly divided into six treatment groups (800 birds per group). Treatments 1 and 4 where placed under feeding program (FP1). Treatments 2, 3, 5, and 6 where placed under a different feeding program (FP2). Three different feed formulations were used, treatments 1 and 4 received formulation (A), treatments 2 and 5 received formulation (B), and treatments 3 and 6 received formulation (C). The treatments 1, 2, and 3 did not receive chromium (NC), while treatments 4, 5, and 6 did receive chromium (C). These birds were reared in 96, 5’X10’ (50 ft2) floor pens, at a stocking density of 1.00 ft2/bird (50 birds per pen). Throughout the duration of the trial bird performance was measured. Average body weight, feed conversion ratio, feed consumed, and percent mortality was collected at the change of each feed phase. From the results of this study there was no significant effect on broiler performance from the supplementation of chromium, feed formulation, and feeding program. Although, the results on Table 14 from the yield study shows that treatment 2 was significantly different from treatments 1, 3, and 4 in front half carcass weight, however, was not significantly different from treatments 5 and 6. Table 14 results also show treatment 2 having significant differences from treatments 1 and 4 in breast meat yield, however was not significantly different from treatments 3, 5, and 6. However, there is a possibility that these areas of significance in the yield study could be false positives found in the data of this single trial. Additional studies should be conducted to further the assumption if there is an actual significant difference between the treatments

    Spherical GEMs for parallax-free detectors

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    We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical \textsc{gem}s are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This would eliminate the parallax error for detection of x-rays, neutrons or UV photons when a gaseous converter is used. This parallax error limits the spatial resolution at wide scattering angles. The method is inexpensive and flexible towards possible changes in the design. We show advanced plans to make a prototype of an entirely spherical triple-GEM detector, including a spherical readout structure. This detector will have a superior position resolution, also at wide angles, and a high rate capability. A completely spherical gaseous detector has never been made before.Comment: Contribution to the 2009 IEEE Nuclear Science Symposium, Orlando, Florid
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