KIP-Veröffentlichungen

A still puzzling problem in the development of low temperature microcalorimeters
for the measurement of the 187rhenium β-spectrum is the understanding
of the thermalization of energetic electrons in the superconducting rhenium absorber.
We studied metallic magnetic calorimeters (MMC) with single crystal rhenium absorbers
and paramagnetic Au:Er temperature sensors. The energy released into the
detector leads to a change of magnetization of the paramagnetic sensor located in a
weak magnetic field. A SQUID with meander shaped inductance is used to read out
this change. This setup allows the study of several properties of the superconducting
absorber. The transition to the superconducting state is studied by measuring the
magnetic flux expelled by the rhenium sample. The resistivity of rhenium above Tc
can be estimated from the measurement of the spectral power density of the Johnson
noise. Furthermore the quasiparticle lifetime can be investigated through the analysis
of the shape of detector signals caused by intrinsic β-decays and the absorption of
X-rays. We present the data obtained in these experiments and discuss the physical
quantities which can be derived from these.