KIP publications

In the last years metallic magnetic calorimeters (MMC) showed an energy
resolution of a few eV for x-rays up to 10 keV. This makes MMCs a promising and
powerful tool for many applications where photons or energetic massive particles
have to be detected—like absolute activity measurements of radioactive isotopes,
high resolution x-ray spectroscopy and x-ray fluorescence material analysis. However,
in order to fulfill all requirements of these applications and to allow to reach
the maximum resolving power a consequent micro-fabrication of the MMC detectors
is needed. The micro-fabrication of metallic magnetic calorimeters requires reliable
deposition and patterning processes for niobium structures with high critical currents
and for paramagnetic sensors.
As one result of our advances in microstructuring a fully microfabricated MMC
which consists of a meander shaped niobium thin film pickup coil and a 3 μm thick
sputter deposited paramagnetic Au:Er temperature sensor will be presented. Deposition
of energy in the paramagnetic sensor causes a rise in temperature and results
in a change of magnetization, which is measured by a low noise high bandwidth dc-
SQUID. The sputter deposited Au:Er films we report on are working well and show
thermodynamic properties close to the ones known from bulk material down to temperatures
of 45 mK.