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trigger [2013/12/11 14:27]
pereira |
trigger [2013/12/11 14:36]
pereira [Trigger Box] |
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| ==== Trigger Box ==== | ==== Trigger box ==== |
| In addition to the singles and coincidence triggers, two separate trigger sources labeled "External 1" and "External 2" can be used. The various sources can be selected from the trigger box to define the raw trigger, which is then sent to a third AND gate for computer busy rejection. The busy latch (on the middle) is set by the raw trigger after a 50 ns delay, and prevents subsequent events to be accepted. It is reset by the computer once the current event has been processed. The live trigger signal feeds several gate generators which provide appropriate gates for the ADCs, QDCs, TDCs and an eventual coincidence register. Note that the trigger box contains its own coincidence register for which the input signals are delayed by 50 ns, and the gate width is set by the coincidence gate generator. The request event signal is latched before being sent to the computer. | In addition to the singles and coincidence triggers, two separate trigger sources labeled "External 1" and "External 2" can be used. The various sources can be selected from the trigger box to define the raw trigger, which is then sent to a third AND gate for computer busy rejection. The busy latch (on the middle) is set by the raw trigger after a 50 ns delay, and prevents subsequent events to be accepted. It is reset by the computer once the current event has been processed. The live trigger signal feeds several gate generators which provide appropriate gates for the ADCs, QDCs, TDCs and an eventual coincidence register. Note that the trigger box contains its own coincidence register for which the input signals are delayed by 50 ns, and the gate width is set by the coincidence gate generator. The request event signal is latched before being sent to the computer. |
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| ====== Scalers and dead time ====== | ====== Scalers and dead time ====== |
| The "D" connector of the trigger module is directly connected to 16 inputs of a scaler module (see mapping in the inputs and outputs section below). Scalers are connected to each of the trigger source inputs, as well as trigger box inputs. These scalers can be used to recover the number of trigger signals occurring on each of the source and trigger box inputs, in addition to the information coded for each event in the trigger register. | The "D" connector of the trigger module is directly connected to 16 inputs of a scaler module (see mapping of the inputs and outputs of the trigger module in section [[Trigger#Inputs and outputs|Inputs and outputs]]). Scalers are connected to each of the trigger source inputs, as well as trigger box inputs. These scalers can be used to recover the number of trigger signals occurring on each of the source and trigger box inputs, in addition to the information coded for each event in the trigger register. |
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| In addition, scalers are connected to the raw and live trigger signals. For the determination of the dead time, both a free running and vetoed 10 kHz pulser signal are also connected to scalers. This is the preferred method because the pulser is not subject to possible double triggering effects like the raw trigger. | In addition, scalers are connected to the raw and live trigger signals. For the determination of the dead time, both a free running and vetoed 10 kHz pulser signal are also connected to scalers. This is the preferred method because the pulser is not subject to possible double triggering effects like the raw trigger. |
