Abstract: Disclosed herein is a method of determining information regarding the location of energy deposition of an ion beam in an absorptive medium, comprising the following steps: generating a pulsed ion beam, detecting a time-resolved acoustic signal, said time-resolved acoustic signal comprising an energy-deposition-signal component attributable to the energy deposition of an individual pulse of said pulsed ion beam in said absorptive medium, determining relative timing information of the energy deposition of said individual pulse with respect to said time-resolved acoustic signal, providing a matched filter for processing the time-resolved acoustic signal, and applying said matched filter to said time-resolved acoustic signal, deriving, from the filtered time-resolved signal, occurrence timing information related to the occurrence of said energy-deposition signal component in said time-resolved acoustic signal, and deriving information regarding the location of the energy deposition based, at least in part, on a d