Time measurements by means of digital sampling techniques: a study case of 100 ps FWHM time resolution with a 100 MSample/s, 12 bit digitizer

An application of digital sampling techniques is presented which can simplify experiments involving sub-nanosecond time-mark determinations and energy measurements with nuclear detectors, used for Pulse Shape Analysis and Time of Flight measurements in heavy ion experiments. The basic principles of the method are discussed as well as the main parameters that influence the accuracy of the measurements. The method allows to obtain both time and amplitude information with an electronic chain simply consisting of a charge preamplifier and a fast high resolution ADC (in the present application: 100 MSample/s, 12 bit) coupled to an efficient on-line software. In particular an accurate Time of Flight information can be obtained by mixing a beam related time signal with the output of the preamplifier. Examples of this technique applied to Silicon detectors in heavy-ions experiments involving particle identification via Pulse Shape analysis and Time of Flight measurements are presented. The system is suited for applications to large detector arrays and to different kinds of detectors.