Introduction of the trigger system and the measurement for trigger efficiency at L3 + cosmic experiment

The trigger process of L3 + Cosmic experiment at CERN is introduced briefly. Also the authors checked whether the settings of L3 + Cosmic trigger system by simulation are correct or not and introduced a method on trigger efficiency calculation. To get trigger efficiency for μ spectrum measurement, an experimental data sample, which includes events passing the trigger set to measure the μ spectrum and not passing, is needed. Then L3 + C trigger process is simulated with these events in this sample to know how many events should pass the trigger. By checking a trigger bit recorded in the experimental data, one can know how many events passed the trigger in hardware in these simulated events. The ratio then determines the trigger efficiency for μ spectrum measurement. And the systematic error is analyzed. The results on trigger efficiency have been used to the measurement of μ spectrum