Edited sentence: A small completely normally conducting section across the width of the nanowire is formed.Absorption of a photon destroys a number of Cooper pairs, enough to reduce the critical current below the bias current.Such a normally conducting section then leads to a detectable voltage pulse of a duration of about 1 ns.Superconductors can be used for photon detectors even at temperatures well below the superconducting transition temperature (in contrast to transition edge detectors) when they are biased with a constant current close to the superconducting critical current (e.The main advantages of this type of photon detectors are its high speed (a maximal counting rate of up to 2 GHz makes them the fastest available) and.Their main disadvantage is the limited energy resolution.This type of photon detector takes advantage of the distinct properties of superconducting thin films (usually ≈ 5 nm thick NbN) which are structured as thin nanowires (with a possible width down to about 50 nm).its low dark count rate.with 95 % of the critical current)