Luminosity block

In the ATLAS experiment, a luminosity block (LB) is a time interval of data recording over which the experimental conditions are assumed to be constant. In particular, it is assumed that the instantaneous luminosity is constant over the duration of the luminosity block. Luminosity blocks are set by the ATLAS central trigger processor and their duration is usually around one minute. If the data-recording configuration changes, e.g. if a trigger prescale is adjusted, a new luminosity block is started.