Simulating Sensor Sampling Effects On Ultrafast Timing Resolution

Techniques using the pump and probe method, such as Ultrafast Electron Diffraction (UED), allow us to peer into the behavior of phenomena that unfold on femtosecond time scales. However, verifying the time separation between the pump and probe pulses using direct measurement of the time of passage of the beam pulses has been beyond the capability of ionizing-particle detection systems. An effort underway within the Advanced Accelerator Diagnostics (AAD) collaboration is developing ultrafast (multi-GHz) detection systems that may offer the possibility of femtosecond timing.

In this presentation, I explore the possible limitations imposed by the finite waveform sampling rate of multi-GHz voltage signals on the ability to resolve the time-of-arrival of intense beam pulses. The work is based on a Monte Carlo simulation of the performance of an ideal electronic readout chip, and explores the parameter space formed by the bandwidth, signal-to-noise, and sampling rate of the chip. In addition to the general parameter space, results are presented for the specific case of the 40 gigasample per second sampling rate of the AAD collaboration’s Fastpulse Precision Sampler readout chip.