Scientific Colloquium
November 30, 2012

"The Thermal Detection of Energy Quanta"

The increase in temperature of a mass volume following the absorption of energy defines the calorie, but yet this direct approach to measuring the energy of individual light or particle quanta has not been generally used as a means for high-resolution spectroscopy. The notion of a micro-calorimeter to directly measure the energy of individual x-rays was developed and pioneered here at Goddard thirty years ago and has enabled numerous scientific endeavors and orbiting observatories. The initial theoretical prediction that the energy of individual x-ray photons could be measured to a part in several thousand, or about 1 electron-volt, took years of research to approach, having to first solve the problem of completely thermalizing electromagnetic radiation quanta, but this has been achieved. Further, it is now possible to fabricate large arrays of these devices, offering the capability of x-ray cameras with thousands of colors in the x-ray band, and with very high sensitivity. In this talk we present the story of this technological development, the challenges in implementing these devices, and describe some of the many applications and plans for the future.

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