Orateur
Description
We present a study of TES and SQUID noise mechanisms combining analytical modelling and experimental characterization. A fi rst aspect of this work focuses on the development of transfer-function formulations for the different detector current noise contributions, including phonon noise, TES intrinsic noise and shunt resistance noise. This formalism highlights the characteristic frequencies governing the detector response and allows direct interpretation of the measured amplitude spectral densities as a function of TES operating point.
A second aspect concerns the extraction of TES electrothermal parameters from bias-step measurements. We analyse the transient response of TES detectors to square-wave bias perturbations and identify the characteristic exponential decays associated with the electrical and thermal dynamics of the sensor.
For those spectral and bias-step measurements, a superconducting transition R(T,I) of the TES is modelled. This model is then used to investigate how the working point within the superconducting transition modifi es both the temporal response and the noise spectral density behaviour.
These approaches provide a framework for characterizing superconducting detectors without requiring direct thermometry of the suspended TES membrane, and contribute to the optimization of cryogenic detector operation for future low-noise cosmology instruments.