J Low Temp Phys (2008) 151: 771–776 DOI 10.1007/s10909-008-9745-2 Feasibility Investigation of NbN Nanowires as Detector in Time-of-Flight Mass Spectrometers for Macromolecules of Interest in Biology (Proteins) D. Perez de Lara · M. Ejrnaes · A. Casaburi · M. Lisitskiy · R. Cristiano · S. Pagano · A. Gaggero · R. Leoni · G. Golt’sman · B. Voronov Received: 23 July 2007 / Accepted: 5 October 2007 / Published online: 15 January 2008 © Springer Science+Business Media, LLC 2008 Abstract We are investigating the possibility of using NbN nanowires as detectors in time-of-flight mass spectrometers for investigation of macromolecules of interest in biology (proteins). NbN nanowires could overcome the two major drawbacks en- countered so far by cryogenic detectors, namely the low working temperature in the mK region and the slow temporal response. In fact, NbN nanowires can work at 5 K and the response time is at least a factor 10–100 better than that of other cryogenic detectors. We present a feasibility study based on a numerical code to calculate the response of a NbN nanowire. The parameter space is investigated at different ener- gies from IR to macromolecules (i.e. from eV to keV) in order to understand if larger value of film thickness and width can be used for the keV energy region. We also present preliminary experimental results of irradiation with X-ray photons of NbN to simulate the effect of macromolecules of the same energy. Keywords Superconducting detectors · Mass spectrometry · Hot spot model · NbN nanowires · Macromolecules PACS 85.25.Am D. Perez de Lara () · M. Ejrnaes · A. Casaburi · M. Lisitskiy · R. Cristiano C.N.R. Istituto di Cibernetica, 80078 Pozzuoli (NA), Italy e-mail: dperezla@fis.ucm.es S. Pagano Dip. di Fisica, Università di Salerno, 84081 Baronissi (SA), Italy A. Gaggero · R. Leoni C.N.R. Istituto di Fotonica e Nanotecnologie, 00156 Rome, Italy G. Golt’sman · B. Voronov Moscow State Pedagogical University, Moscow 119345, Russia