Data Integrity Checksum for the Nab DAQ System

An isolated neutron is unstable, and beta decays into a proton, electron, and antineutrino in about 15 minutes. The Neutron "a" and "b" (Nab) experiment will measure the neutrino angular correlation parameter 'a' to test CKM unitarity and the Fierz interference term 'b' to search for new physics. In this experiment, the proton and neutron waveforms for each decay event are read out by the data acquisition system (DAQ). To ensure these waveforms are read from the proper memory location and not corrupted anywhere throughout the entire digital signal processing chain, we generate a check code digesting the channel number, clock cycle, and ADC waveform data for each word written to the on-board ring buffer. Upon readout, the check codes are processed for validation of the requested time range, including modifications for compatibility with decimated and compressed waveform data. This checkcode algorithm will be implemented in the DAQ FPGA firmware and the corresponding validation code implemented in the waveform analysis software.