Nondetection of Titan lightning radio emissions with Cassini/RPWS after 35 close Titan flybys

We report on the nondetection of radio emissions associated with possible lightning flashes in Titan's atmosphere by the Cassini/RPWS (Radio and Plasma Wave Science) instrument. A valid proof for Titan lightning would be the detection of a number of bursty radio signals above Titan's ionospheric cutoff frequency, and they should be grouped near the closest approach of Cassini to Titan with an approximately quadratic fall off of signal intensity with spacecraft distance. Such a clear signature has not been detected by the RPWS instrument during the first 35 close flybys of Titan.