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Transition edge sensor microcalorimeters can be used in many optical quantum measurements because of its low dark counts, high quantum efficiency, and high resolving power of a photon number in weak light pulses. In order to increase count rates up to a few MHz, we have developed a titanium transition edge sensor for the optical measurements, and its performances were analysed. Titanium is one of the ideal superconductor because of its higher transition temperature and lower optical reflectance at 1.5 μm wavelength. Our titanium film was fabricated with electron-beam evaporation, and showed high residual resistance ratio of 3.5. The sharp superconducting transition also was found at 359 mK, which is close to the critical temperature in bulk. The fabricated device showed a fast response to pulsed laser illumination of 1.5 μm wavelength with the fall time constant of 300 as. These features are very promising for high-speed single photon detection in many quantum optical measurements. [ABSTRACT FROM AUTHOR]

In recent years, cryogenic microcalorimeters using their superconducting transition edge have been under development for possible application to the research for astronomical X-ray observations. To improve the energy resolution of superconducting transition edge sensors (TES), several correction methods have been developed. Among them, a clustering method based on digital signal processing has recently been proposed. In this paper, we applied the clustering method to Ir/Au bilayer TES. This method resulted in almost a 10% improvement in the energy resolution. Conversely, from the point of view of imaging X-ray spectroscopy, we applied the clustering method to pixellated Ir/Au-TES devices. We will thus show how a clustering method which sorts signals by their shapes is also useful for position identification. [ABSTRACT FROM AUTHOR]

Spatial uniformity of superconducting tunnel junction detectors with a size of 200 μm is improved by increasing Al thickness of the Nb/Al proximized electrodes in an energy range of 5-10 keV. which is in the same order as an acceleration energy in time-of-flight mass spectroscopy (TOF-MS). It has been confirmed in the TOF experiments with Ta ions and Ta clusters that the proximized junction detectors clearly separate different ionic states and multi-hit events in impact energy spectra, and moreover can reveal the difference in ion species or ion-surface collision dynamics. However, a better spatial uniformity is not always good for TOF-MS, possibly because a detector with the thicker Al layers has a lower superconducting energy gap, which results in an improper detector operation because of a temperature rise due to heat radiation, or the states of the detector surfaces are different. [ABSTRACT FROM AUTHOR]

The superconducting-transition-edge temperature sensors (TES) for calorimeters operate in an intermediate state within normal-superconducting transition. The spatial profiles of a response to an x-ray microbeam exhibit that normal-superconducting phase separation occurs in an iridium TES with electrothermal feedback, as has been observed in many current-carrying conductors with self-heating. The resistive domain (normal region) in the 500 µm-square TES grows as applied bias voltage increases. This observation agrees reasonably well with a one-dimensional model of the self-heating. On the other hand, two-dimensional features are explained by nonuniform supercurrent distribution in the superconducting domain. These findings are important for developing detectors with a large detection area for energy dispersive x-ray spectroscopy. [ABSTRACT FROM AUTHOR]

Examines superconducting calorimeters developed using transition edge sensors (TES) for industrial x-ray microanalysis. Format array of the sensors; Integration of a TES calorimeter and superconducting quantum interference device amplifier; Current noise of the calorimeter.

We have developed the parallel-biased small-pixel TES, which has a pixel size of 20 μm. The TES pixels are made of Iridium, and some pixels are on a SiN membrane but others are not. Signals from the synchrotron radiation energy X-ray beam are saturated and both the rise and fall times are around a few μsec. The duration time of this pseudo-digital shaped output signal is proportional to the incident energy. This pseudo-digital operation mode may lead to new read-out systems for TES. [ABSTRACT FROM AUTHOR]

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