[Olympus] Trigger for data taking

[Alexander Winnebeck]

Dear colleagues,

as discussed this morning I measured some trigger rates to have some real numbers in hand.
I measured the free trigger rates of different conditions at a beam current of approximately 65 mA and 0.8 sccm target flow.

TOF left right coincidence (trigger34) : 5 kHz
trigger34 without coincidence of inner most bars (34nf): 4.4 kHz
trigger34 without coin. of the two inner most bars (34nff): 3.9 kHz
kinematic trigger (kin75): 2.4 kHz 

Our maximum readout rate is about 2 kHz (please correct me if I'm wrong) depending on the amount of lumi triggers, because our dead time here is much higher.
In parallel we have approximately 200 Hz secondary triggers, like lumi triggers, single arms etc.

Since we do not want to have a high dead time ( should be in the order of 30% or less), we have can not afford an open trigger like trigger34. Even when discarding the two most forward bars for forward forward coincidence the open trigger can not provide a reasonable dead time.

Therefore I propose to stay with the kinematic trigger as main trigger. Maybe we can check on the rates when we add an additional bar at both ends of the accepted range.

The trigger elog contains some remarks and explanations about the triggers. If you have question do not hesitate to ask, because we have to get this settled very soon.

Cheers,

Alexander 
--
Dr. Alexander Winnebeck
winnebeck at mit.edu

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