We present a facile approach that achieves four-point electrical characterization of silicon microwires fabricated using a bottom-up vapour-liquid-solid process. Tungsten probes are brought into ...direct contact with silicon microwires using piezoelectrically driven probe actuators. This technique can be applied to silicon microwires without the need for high-temperature lithographic preparation or the additional use of In/Ga to ensure reliable electrical contact between the probe and the wire. Comparison between two-point probe and four-point probe measurements demonstrates the robustness of the four-point approach. Significantly, the four-point characterization technique is not impacted by native oxides at the microwire/tungsten probe interface. The four-point technique can be applied to sense electrical responses in half-cell and full-cell representations of artificial photosynthesis systems, regardless of catalysts or functional groups attached to the microwire sidewalls.
We present a facile approach that achieves four-point electrical characterization of silicon microwires fabricated using a bottom-up vapour-liquid-solid process.
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We report a precision measurement of the parity-violating asymmetry A PV in the elastic scattering of longitudinally polarized electrons from 208 Pb . We measure APV=550±16(stat)±8(syst) parts per ...billion, leading to an extraction of the neutral weak form factor FW(Q2=0.00616 GeV2)=0.368±0.013 . Combined with our previous measurement, the extracted neutron skin thickness is Rn−Rp=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of 208 Pb: ρW0=− 0.0796 ± 0.0036 ( exp ) ± 0.0013 ( theo ) fm−3 leading to the interior baryon density ρb0 = 0.1480 ± 0.0036 ( exp ) ± 0.0013 ( theo ) fm −3. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.
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We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts ...per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616 GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo) fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo) fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.
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We report precision determinations of the beam normal single spin asymmetries (\(A_n\)) in the elastic scattering of 0.95 and 2.18~GeV electrons off \(^{12}\)C, \(^{40}\)Ca, \(^{48}\)Ca, and ...\(^{208}\)Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of \(A_n\) for \(^{40}\)Ca and \(^{48}\)Ca are found to be similar to that of \(^{12}\)C, consistent with expectations thus demonstrating the validity of theoretical calculations for nuclei with Z~\(\leq20\). We also report \(A_n\) for \(^{208}\)Pb at two new momentum transfers (Q\(^2\)) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the \(Z\leq 20\) nuclei. These data confirm our basic understanding of the underlying dynamics that govern \(A_n\) for nuclei containing \(\lesssim 50\) nucleons, but point to the need for further investigation to understand the unusual \(A_n\) behaviour discovered for scattering off \(^{208}\)Pb.
We report a precise measurement of the parity-violating asymmetry \(A_{\rm PV}\) in the elastic scattering of longitudinally polarized electrons from \(^{48}{\rm Ca}\). We measure \(A_{\rm PV} ...=2668\pm 106\ {\rm (stat)}\pm 40\ {\rm (syst)}\) parts per billion, leading to an extraction of the neutral weak form factor \(F_{\rm W} (q=0.8733\) fm\(^{-1}) = 0.1304 \pm 0.0052 \ {\rm (stat)}\pm 0.0020\ {\rm (syst)}\) and the charge minus the weak form factor \(F_{\rm ch} - F_{\rm W} = 0.0277\pm 0.0055\). The resulting neutron skin thickness \(R_n-R_p=0.121 \pm 0.026\ {\rm (exp)} \pm 0.024\ {\rm (model)}\)~fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.
We report a precision measurement of the parity-violating asymmetry \(A_{PV}\) in the elastic scattering of longitudinally polarized electrons from \(^{208}\)Pb. We measure \(A_{PV}=550\pm 16 {\rm ...(stat)}\pm 8\ {\rm (syst)}\) parts per billion, leading to an extraction of the neutral weak form factor \(F_W(Q^2 = 0.00616\ {\rm GeV}^2) = 0.368 \pm 0.013\). Combined with our previous measurement, the extracted neutron skin thickness is \(R_n-R_p=0.283 \pm 0.071\)~fm. The result also yields the first significant direct measurement of the interior weak density of \(^{208}\)Pb: \(\rho^0_W = -0.0796\pm0.0036\ {\rm (exp.)}\pm0.0013\ {\rm (theo.)}\ {\rm fm}^{-3}\) leading to the interior baryon density \(\rho^0_b = 0.1480\pm0.0036\ {\rm (exp.)}\pm0.0013\ {\rm (theo.)}\ {\rm fm}^{-3}\). The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.
Reviews and discusses Blaikie, P. M., The political economy of soil erosion in developing countries, (London: Longman, 1985). Includes a response by the author (Original abstract-amended)
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CEKLJ, DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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