194 research outputs found

    Mean left-right eigenvector self-overlap in the real Ginibre ensemble

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    We study analytically the Chalker-Mehlig mean diagonal overlap O(z)\mathcal{O}(z) between left and right eigenvectors associated with a complex eigenvalue zz of N×NN\times N matrices in the real Ginibre ensemble (GinOE). We first derive a general finite NN expression for the mean overlap and then investigate several scaling regimes in the limit NN\rightarrow \infty. While in the generic spectral bulk and edge of the GinOE the limiting expressions for O(z)\mathcal{O}(z) are found to coincide with the known results for the complex Ginibre ensemble (GinUE), in the region of eigenvalue depletion close to the real axis the asymptotic for the GinOE is considerably different. We also study numerically the distribution of diagonal overlaps and conjecture that it is the same in the bulk and at the edge of both the GinOE and GinUE, but essentially different in the depletion region of the GinOE.Comment: 23 pages, 7 figure

    Characterization of a new commercial single crystal diamond detector for photon- and proton-beam dosimetry

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    A synthetic single crystal diamond detector (SCDD) is commercially available and is characterized for radiation dosimetry in various radiation beams in this study. The characteristics of the commercial SCDD model 60019 (PTW) with 6- and 15-MV photon beams, and 208-MeV proton beams, were investigated and compared with the pre-characterized detectors: Semiflex (model 31010) and PinPoint (model 31006) ionization chambers (PTW), the EDGE diode detector (Sun Nuclear Corp) and the SFD Stereotactic Dosimetry Diode Detector (IBA). To evaluate the effects of the pre-irradiation, the diamond detector, which had not been irradiated on the day, was set up in the water tank, and the response to 100 MU was measured every 20 s. The depth–dose and profiles data were collected for various field sizes and depths. For all radiation types and field sizes, the depth–dose data of the diamond chamber showed identical curves to those of the ionization chambers. The profile of the diamond detector was very similar to those of the EDGE and SFD detectors, although the Semiflex and PinPoint chambers showed volume-averaging effects in the penumbrae region. The temperature dependency was within 0.7% in the range of 4–41°C. A dose of 900 cGy and 1200 cGy was needed to stabilize the chamber to the level within 0.5% and 0.2%, respectively. The PTW type 60019 SCDD detector showed suitable characteristics for radiation dosimetry, for relative dose, depth–dose and profile measurements for a wide range of field sizes. However, at least 1000 cGy of pre-irradiation will be needed for accurate measurements

    Thin film solar cells based on the ternary compound Cu2SnS3

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    Alongside with Cu2ZnSnS4 and SnS, the p-type semiconductor Cu2SnS3 also consists of only Earth abundant and low-cost elements and shows comparable opto-electronic properties, with respect to Cu2ZnSnS4 and SnS, making it a promising candidate for photovoltaic applications of the future. In this work, the ternary compound has been produced via the annealing of an electrodeposited precursor in a sulfur and tin sulfide environment. The obtained absorber layer has been structurally investigated by X-ray diffraction and results indicate the crystal structure to be monoclinic. Its optical properties have been measured via photoluminescence, where an asymmetric peak at 0.95 eV has been found. The evaluation of the photoluminescence spectrum indicates a band gap of 0.93 eV which agrees well with the results from the external quantum efficiency. Furthermore, this semiconductor layer has been processed into a photovoltaic device with a power conversion efficiency of 0.54%, a short circuit current of 17.1 mA/cm2, an open circuit voltage of 104 mV hampered by a small shunt resistance, a fill factor of 30.4%, and a maximal external quantum efficiency of just less than 60%. In addition, the potential of this Cu2SnS3 absorber layer for photovoltaic applications is discussed

    Noise of short-time integrators for readout of uncooled infrared bolometer arrays

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    Abstract. As state-of-the-art readout circuits short-time integrators in Far Infrared (FIR) uncooled bolometer arrays are commonly used. This paper compares the transfer functions of an ideal continuous-time integrator with that of a real integrator with focus an OTA parameters and noise analysis. Beside the noise sources at the non-inverting input of the OTA special care has to be taken to account for capacitances at the inverting input. The Noise Equivalent Temperature Difference (NETD) as the key parameter for bolometer applications for a real short-time integrator will be derived. As the result it will be shown, that the NETD is 1/f -noise limited
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