Scientific Colloquium
November 30, 2012
RICHARD
KELLEY
GODDARD SPACE FLIGHT CENTER
"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.