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AssigneeXia LLC
InventorsWilliam K. Warburton, Jackson T. Harris
Estimating the term…
A technique for characterizing the noise behavior of a superconducting tunnel junction (STJ) detector as a function of its applied bias voltage Vb by stepping the STJ's bias voltage across a predetermined range and, at each applied bias, making multiple measurements of the detector's current, calculating their mean and their standard deviation from their mean, and using this standard deviation as a measure of the STJ detector's noise at that applied bias. Because the method is readily executed under computer control, it is particularly useful when large numbers of STJ detectors require biasing, as in STJ detector arrays In a preferred implementation, the STJ is measured under computer control by attaching it to a digital spectrometer comprising a digital x-ray processor (DXP) coupled to a preamplifier that can set the STJ's bias voltage Vb using a digital-to-analog converter (DAC) controlled by the DXP. An on-board digital-signal-processor in the DXP is then programmed to implement the technique by stepping through a sequence of bias voltages using the DAC and, for each voltage, capturing 1000 values of the detector current Id from the DXP's baseline filter and then computing their mean <Id> and standard deviation σId. Minima in the plot of σId. vs Vb are shown to correspond to minima in the plot of detector energy resolution vs Vb, allowing a plot or table of σId. vs Vb values to be used to locate an optimum value of Vb for the detector operating point.
A method for generating a noise curve to characterize the noise in a superconducting tunnel junction (STJ) detector as a function of its applied bias voltage by:
A method for generating a noise curve to characterize the noise in a superconducting tunnel junction (STJ) detector as a function of its applied bias voltage by:
Apparatus for generating a noise curve to characterize the noise in a superconducting tunnel junction (STJ) detector as a function of its applied bias voltage, the apparatus comprising:
Dependencies are inferred from the claim text.