21,832 research outputs found

    Large Area Crop Inventory Experiment (LACIE). Level 3 baseline; LACIE commodity data control plan for JSC

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    Thermotropic Nematic and Smectic Order in Silica Glass Nanochannels

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    Optical birefringence measurements on a rod-like liquid crystal (8OCB), imbibed in silica channels (7 nm diameter), are presented and compared to the thermotropic bulk behavior. The orientational and positional order of the confined liquid evolves continuously at the paranematic-to-nematic and sizeably broadened at the nematic-to-smectic order transition, resp., in contrast to the discontinuous and well-defined second-order character of the bulk transitions. A Landau-de-Gennes analysis reveals identical strengths of the nematic and smectic ordering fields (imposed by the walls) and indicates that the smectic order is more affected by quenched disorder (originating in channel tortuosity and roughness) than the nematic transition.Comment: 3 pages, 4 figure

    Which long-baseline neutrino experiments are preferable?

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    We discuss the physics of superbeam upgrades, where we focus on T2KK, a NuMI beam line based experiment NOvA*, and a wide band beam (WBB) experiment independent of the NuMI beam line. For T2KK, we find that the Japan-Korea baseline helps resolve parameter degeneracies, but the improvement due to correlated systematics between the two detectors (using identical detectors) is only moderate. For an upgrade of NOvA with a liquid argon detector, we demonstrate that the Ash River site is preferred compared to alternatives, such as at the second oscillation maximum, and is the optimal site within the U.S. For a WBB experiment, we find that high proton energies and long decay tunnels are preferable. We compare water Cherenkov and liquid argon technologies, and find the break-even point in detector cost at about 4:1. In order to compare the physics potential of the different experimental configurations, we use the concept of exposure to normalize the performance. We find that experiments with WBBs are the best experimental concept. NOvA* could be competitive with sufficient luminosity. If sin22θ13\sin^2 2\theta_{13} > 0.01, a WBB experiment can perform better than a neutrino factory.Comment: 31 pages, 13 figures, 5 tables. Version to appear in PR

    Influence of nano confinement on nematic liquid crystals

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    We explore the nematic ordering of the rod-like liquid crystals 5CB and 6CB, embedded into parallel-aligned nanochannels in mesoporous silicon and silica membranes as a function of mean channel radius (4.7<=R <=8.3 nm), and thus geometrical confinement strength, by optical birefringence measurements in the infrared region. The orientational order inside the nanochannels results in an excess birefringence, which is proportional to the nematic order parameter. It evolves continuously upon cooling with a precursor behavior, typical of a paranematic state at high temperatures. These observations are compared with the bulk behavior and analyzed within a phenomenological model. Such an approach indicates that the strength of the nematic ordering fields sigma is beyond a critical threshold sigma_c =1/2, that separates discontinuous from continuous paranematic-to-nematic behavior. In agreement with the predictions of the phenomenological approach a linear dependency of sigma on the inverse channel radius is found and we can infer therefrom the critical channel radii, R_c, separating continuous from discontinuous paranematic-to-isotropic behavior, for 5CB (12.1 nm) and 6CB (14.0 nm). Our analysis suggests that the tangential anchoring at the channel walls is of similar strength in mesoporous silicon and mesoporous silica membranes. A comparison with the bulk phase behavior reveals that the nematic order in nanoconfinement is significantly affected by channel wall roughness leading to a reduction of the effective nematic ordering.Comment: 7 pages, 5 figure

    Upgraded experiments with super neutrino beams: Reach versus Exposure

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    We introduce exposure as a means to making balanced comparisons of the sensitivities of long-baseline neutrino experiments to a nonzero \theta_{13}, to CP violation and to the neutrino mass hierarchy. We illustrate its use by comparing the sensitivities of possible upgrades of superbeam experiments, namely NOvA*, T2KK and experiments with wide band beams. For the proposed exposures, we find the best nominal CP violation performance for T2KK. For equal exposures, a wide band beam experiment has the best mass hierarchy performance. The physics concept on which NOvA* is based has the best potential for discovering CP violation only for exposures above a threshold value.Comment: 4 pages, 2 figures, 1 table. Version to appear as a Rapid Communication in PR
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