PoS(VERTEX 2010)020  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it Charge multiplication in highly irradiated planar silicon sensors Gianluigi Casse University Of Liverpool, Physics Department O. Lodge Lab., Oxford street, L69 7ZE, Liverpool, UK. E-mail: gcasse@hep.ph.liv.ac.uk. The discovery of the novel effect that amplifies the charge generated by ionising particles in heavily irradiates silicon detectors has risen hopes for further extending the lifetime of this type of sensors when exposed to heavy doses of hadron irradiation. The anomalous size (compared to expectations) of the signal generated by a minimum ionising particle (mip) in detectors irradiated to doses about one order of magnitude higher than what anticipated for the current Large Hadron Collider (LHC) at CERN has been reported for a number of years. It is now well documented that the correct interpretation for the improvement of the charge collection resides in the multiplication of the signal charge by impact ionisation. This effect is being intensively studied within the high energy physics detector community by mean of both experiments and simulations. The results of these studies are particular relevant to the silicon detectors planned for the future super LHC (sLHC) and for every silicon sensor that will be intended for very hostile environment, where the final cumulated flux will reach level of a few times 10 16 1MeV neutron equivalent (n eq ) cm -2 . A summary of the current results and the understood implications and limitations of this effect are here discussed.