Event and Spectrum Data Acquistion Modes

The data sets are labeled with an E (Event Mode) or an S (Spectrum Mode).

Because of the relatively high data rates at the lower energy facilities the early data acquisition systems (whose computers had only modest core memory and slow processor speeds) could write only a limited amount of data to external storage. As a result data was preprocessed on-line and only histogrammed spectra were written to tape or disk. This was known as histogram or spectrum mode (S) and it allowed little off-line analysis.

At the higher energy facilities the data acquisitions systems allowed for a mode of data taking referred to as event-mode (E). In this system all the coordinates and detector pulse height and time information was written out on an event by event basis. This system allowed for an off-line analysis that could correct for hardware shortcomings and potentially allowed for more reliable cross sections.