A GPU Algorithm to Determine the Time-of-Flight of Protons in the Neutron Decay Experiment Nab*

The goal of the Nab experiment is to measure the little ‘a’ and ‘b’ coefficients with a precision of 10$\times 10^{-3}$ and 3$\times 10^{-3}$, respectively. Neutron beta decay is one of the most fundamental processes in nuclear physics that would allow probing of the weak interaction. In order to achieve this, a crucial requirement is determining the time-of-flight of protons with a systematic uncertainty of less than 300 ps to reconstruct the electron energy and estimate proton momentum require for the calculation of the coefficients. The data acquisition system has the potential to continuously stream the full 250 MS/s waveform data from up to 5000 events per second.  In order to keep up with this high data rate in near-line analysis, we have implemented flexible algorithms that utilize the architecture of a massively parallel graphic processor unit (GPU).  A comparison of the extraction algorithms for a number of filters with be presented.