Tamashevich, Y. Elsen, E. Navitski, A. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-TUPB079 English 774-777 TUPB079 cavity detector simulation SRF HOM Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-TUPB079 http://srf2015.vrws.de/papers/tupb079.pdf A compact detector and numerical algorithm for second sound measurements has been developed. The detector allows precise 3D quench localisation within a single unit and can be used even for cavities with mounted helium tank. The compact device is easily mounted and requires minimum space. It can be used as a part of the standard cold test of cavities. The results obtained with the new detector and a 3D algorithm have been cross-checked by optical inspection and resistor-based temperature mapping. The resolution of the detector is seen to be limited by the sampling rate and the lateral extent of the quench induced heated area on the Nb superconductor.