Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 23: Instrumentation

HK 23.6: Talk

Monday, March 4, 2013, 18:15–18:30, WIL-A221

Experimental Determination of the Time and Charge Resolution of a Flash-ADC System for the PANDA STT — •Timm Preuhs, Albrecht Gillitzer, Henner Ohm, and Pawel Kulessa — Forschungszentrum Jülich, Institut für Kernphysik, Deutschland

The PANDA STT detector needs not only a high time resolution for precise spatial reconstruction of the helical trajectories of charged particles but also good deposited energy resolution in order to separate protons, kaons and pions in the momentum region below about 1 GeV/c. Currently a readout system for the PANDA STT based on Flash-ADCs are being investigated as a candidate for the final readout system. This system measures simultaneously pulse-height and time information. While the pulse-height resolution of the system is reasonably well understood, it is not immediately obvious that the timing properties are sufficient. The flash-ADC samples signals with a frequency of 240 MHz so that the spacing between adjacent data points is 4.16 ns. This is too coarse for the required time resolution of the STT. Thus, for timing applications a straight line is fit to the rising slope of a signal and the time of appearance of a signal is then calculated as the intercept of this line with a given signal level. This can provide a better resolution than the period between samples. Long signal integration times needed for full charge collection of signals, however, make the signal slope less steep, thereby reducing the timing resolution. In this presentation the results of the achieved time resolution will be presented for a wide range of signal rise times and amplitudes.