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external beam trigger. Should be clean and free from "empty" triggers. Actually empty triggers will be identified by CU
Very important is to have a "pencil" beam (see above in "Experimental setup" section) to eliminate the events when incident particle misses the ACD due to the beam divergency. Small (1cm by 1cm) triggering scintillator attached just in front of MMS would do the best job
Data Taking Configurations and Relevant Runs
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