Meissner Effect Based Single Particle Detector*

We report on a transitions edge sensor (TES) as a single particle detector that is based on the Meissner Effect (as opposed to the critical current transition). A superconductor below the critical temperature expels all magnetic field inside it. Close to the critical temperature the superconductor will allow for some field to be admitted; hence, it could be used as a calorimeter. Here we have used a Tin thin film as the superconducting absorber (detector), together as Niobium ring for readout. A particle absorbed in the Tin results in a rise in temperature which, in turn changes the strength of the Meissner effect within the Tin, resulting in a redistribution of the magnetic field. This change in the field is detected via the Niobium ring. Preliminary results show the capability of single alpha particle detection and operation at temperatures of several Kelvin.