Event timing device providing subpicosecond precision

We are reporting on the latest experimental results achieved with an event timing device using a surface acoustic wave filter as a time interpolator. During the tests of the first version of the device, the noise of the filter excitation was identified as the dominant source of the measurement error. Therefore a new concept of the excitation with very low level of the noise energy was designed. This new solution led to considerable improvement of the device performance. It results from the experimental measurements that the single shot precision is repeatedly lower than 500 fs RMS when time marks generated synchronously with the time base are measured. When asynchronous time marks are split into two event timers and the resulting time difference is measured, the single shot precision is below 700 fs RMS per channel. In this case the measurement is affected not only by random errors, but also by non-linearity of the time interpolation. The temperature dependence is below 0.1 ps/K. Operating the device in a common laboratory environment without temperature stabilization, the stability TDEV better than 3 fs has been routinely achieved for range of averaging intervals from 10 s to several hours.