S800 Documentation

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trigger [2013/12/11 14:35]
pereira [Scalers and dead time] 		trigger [2013/12/11 14:42]
pereira
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   - Direct visualization of the trigger logic and configuration    - Direct visualization of the trigger logic and configuration 
  
-Probably the most appealing feature of this module is the possibility to remotely control the trigger timing and configuration while beam is present in the vault, since most experiments are nowadays locating their electronics close to the detectors. For more details on this detector check section [[Trigger#Trigger module|Trigger module]].+Probably the most appealing feature of this module is the possibility to remotely control the trigger timing and configuration while beam is present in the vault, since most experiments are nowadays locating their electronics close to the detectors. For more details on this detector check section "[[Trigger#Trigger module|Trigger module]]".
  
  
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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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 ==== Time Stamping Scheme ==== ==== Time Stamping Scheme ====
-Because the USB-based S800 data acquisition uses independent crate controllers that perform the readout in parallel, time stamping and busy schemes are incorporated in the trigger to synchronize events and insure no trigger is generated while readout sequences are being executed. Because of this modularity, adding an external data acquisition system (typically from an external detector), is straightforward. More details about the time stamping can be found [[Trigger#Time Stamping|here]].+Because the USB-based S800 data acquisition uses independent crate controllers that perform the readout in parallel, time stamping schemes are incorporated in the trigger to synchronize events. Because of this modularity, adding an external data acquisition system (typically from an external detector), is straightforward. More details about the time stamping module can be found in section [[Trigger#Time stamping|Time stamping]].
  
  
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-====== Time Stamping ======+====== Time stamping ======
 The S800 trigger provides a vetoed 10 MHz clock signal (derived from the 40 MHz FPGA clock) used for time stamping. An external clock can also be used, after selecting the appropriate check box in the [[Trigger#Trigger Schematic|GUI]]). The clock is inhibited by a "Go" signal controlled by the trigger module. While "Go" is false, all time stamp counters can be reset via CAMAC command, typically during the begin sequences of the controllers or data acquisitions (see section on [[begin sequence]]). The clock signal is released when the "Go" signal is set to true at the end of the begin sequence. This simple scheme insures that all time stamp counters are synchronized.  The S800 trigger provides a vetoed 10 MHz clock signal (derived from the 40 MHz FPGA clock) used for time stamping. An external clock can also be used, after selecting the appropriate check box in the [[Trigger#Trigger Schematic|GUI]]). The clock is inhibited by a "Go" signal controlled by the trigger module. While "Go" is false, all time stamp counters can be reset via CAMAC command, typically during the begin sequences of the controllers or data acquisitions (see section on [[begin sequence]]). The clock signal is released when the "Go" signal is set to true at the end of the begin sequence. This simple scheme insures that all time stamp counters are synchronized. 
  
trigger.txt ยท Last modified: 2023/10/24 16:47 by swartzj

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