Microcalorimeter arrays for ultra-high energy resolution X- and gamma-ray detection

Microcalorimeter detectors provide superior energy resolution for the detection of X-rays and gamma-rays. The technology utilizes a cryogenic transition-edge sensor (TES) coupled to a tin bulk absorber. We are working on fabrication methods for the production of arrays with many sensors. In this paper, we present data collected with an array of microcalorimeters using as many as 26 sensor elements simultaneously. Advances in sensor design have extended the useful dynamic range to photon energies up to ～200 keV, while providing resolution performance in the 80–90 eV FWHM range, significantly better than planar high-purity germanium. These sensor arrays have applications in the measurement of nuclear materials. We present data collected from ¹⁵³Gd, a highly-enriched uranium sample, and a plutonium isotopic standard source. We also demonstrate clean separation of the ²³⁵U 185.715 keV peak from the ubiquitous ²²⁶Ra 186.211 keV background peak interference.     

The determination of caesium 137 in irradiated uranium and irradiated thorium using anion-exchange paper and the ring oven technique

Summary By use of a strongly basic anion-exchange resin paper in the hydroxide or carbonate forms, caesium 137 can be separated from irradiated uranium solutions on a ring oven. A ring oven separation of caesium 137 from irradiated thorium can also be achieved by using an oxalate-hydroxide form resin paper. In each case the caesium 137 is washed to the ring zone with water and determined by-ray spectrometry. The coefficient of variation of the methods is less than 2 per cent.

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Zusammenfassung Mit einem stark basischen Anionenaustauschpapier in der Hydroxid- oder Carbonatform kann¹³⁷Cs aus bestrahlten Uranlösungen auf einem Ringofen abgetrennt werden. Mit einem Oxalat-Hydroxid-Harzpapier läßt sich¹³⁷Cs auch von bestrahltem Thorium auf einem Ringofen trennen. In beiden Fällen wird¹³⁷Cs mit Wasser in die Ringzone gespült und durch-Strahlspektrometrie bestimmt. Die Methoden unterliegen Abweichungen von weniger als 2%.

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Résumé Par l'emploi d'un papier échangeur d'anion sous forme hydroxyde ou carbonate, le césium 137 peut être séparé de solutions d'uranium irradié au four annulaire. On peut aussi séparer, au four annulaire, le césium 137 du thorium irradié, avec un papier résineux sous forme hydroxyde-oxalate. Dans chacun cas, le césium 137 est chassé vers la zone annulaire par de l'eau et déterminé par spectrométrie. Les méthodes peuvent fournir une précision meilleure que 2 pour cent.

     

The Approaching Revolution in X-Ray Microanalysis: The Microcalorimeter Energy Dispersive Spectrometer

A high-resolution energy-dispersive X-ray spectrometer (EDS) based on cryogenic microcalorimeter X-ray detectors has been developed for use in X-ray microanalysis. With an energy resolution of 3 eV at 1.5 keV, count rate of 500 s^–1, and an effective collection area of 5 mm² (using polycapillary X-ray optics), the microcalorimeter EDS combines many of the favorable qualities of commercially-available wavelength dispersive spectrometers (WDS) and semiconductor EDS. After describing the spectrometer system, we present several applications of microcalorimeter EDS to important microanalysis problems.