  We present a set of experiments to optimize the performance of the
noninvasive thermometer based on proximity superconductivity. Current through a
standard tunnel junction between an aluminum superconductor and a copper
electrode is controlled by the strength of the proximity induced to this normal
metal, which in turn is determined by the position of a direct superconducting
contact from the tunnel junction. Several devices with different distances were
tested. We develop a theoretical model based on Usadel equations and dynamic
Coulomb blockade which reproduces the measured results and yields a tool to
calibrate the thermometer and to optimize it further in future experiments.
