Level-1 Trigger Shift PrimEx

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Configuration for Production Runs

Production data is taken with the following configuration. The configuration has to be selected on the RCM Run Config GUI when you start DAQ using rcm.sh (see descriptions at the DAQ page). Make sure that the following config parameters are set:

RAID: gluondaqbuff
DAQVERS: default


Cosmic runs

Configuration files for cosmic runs are BCAL_cosmic_raw.conf (raw waveforms) or BCAL_cosmic_prod.conf (production mode)

Trigger Types

1. GTP Triggers

Currently, the following main Global Trigger Processor (GTP) triggers are used for data production:

Trigger Type Trigger Bit (starting from 1)
PS 4

Trigger bits used in spring 2016 are can be found here.

2. TS Front Pannel Triggers

Several ancillary LED triggers and the random trigger run in parallel to physics triggers. These triggers are distributed through the TS front panel (FP), and are used to monitor detector performance. Each FP trigger type has a specific trigger bit assigned. Trigger bits and corresponding rates are listed in the table below:

Assignment of the TS FP trigger bits and typical trigger rates are shown in the table:

Trigger Type Trigger Bit (starting from 1) Typical rate
FCAL LED 3 10 Hz
BCAL LED 9, 10 (single or both bits can be seen, depending on the bcal LED script) 10 Hz
CCAL LED 5 100 Hz
CCAL Alpha source 6 ~80 Hz
Random 12 100 Hz

The LED and random triggers can be enabled (disabled) using CSS. If you do not see corresponding trigger bits in the online monitoring plots (RootSpy) or the trigger monitor "trig_client", make sure that the corresponding pulsers are enabled using CSS screens for the following subdetectors:

  • FCAL and BCAL LED triggers (bits 3, 9, and 10)

In GlueX production runs, the FCAL and BCAL LEDS are controlled by scripts, which alternate several LED configurations (different LED colors and LED voltages for FCAL, upstream and downstream LEDs for various BCAL columns etc.). In the online monitoring plot one expect to see bits 3 and one (or both) bits 9 and 10. Scrips for both the FCAL and BCAL LED pulsers can be enabled using the CSS "BCALL LED pulser" screen as shown below.

  • Random Trigger (bit 12)

Random trigger can be enabled from the "Random Pulser" screen in the DAQ section of the CSS

If you do not see LED trigger bits for the FCAL/BCAL or DIRC, call to subdetector experts on call.

Trigger Monitor

Trigger rates produced by the detector (generated by the GTP) and also distributed from the TS front pannel can be monitored using trig_client program. To run the program:

  1. Login to the gluon100 machine under hdops and execute trig_client.
  2. If trig_client is already running, you will get the message on the xterm screen.
To restart the client, kill the process and delete the logfile

An example of the trigger monitor screen, is shown below


NOTE: Lane 0 on this plot corresponds to the trigger BIT 1.

Trigger Rates for Production Runs

Trigger rate depends on the luminosity (flux of collimated photons), which can vary for different electron beam currents, radiator types, and tagging efficiency. The photon flux can be measured using the pair spectrometer. Therefore, it is practical to relate the rate of the main physics trigger to the PS rate.

Below are some reference plots of trigger rates for PrimEx production runs. The nominal electron beam current for production runs is 200 nA.

Fig. 1

  • DAQ dead time

The typical DAQ dead time for main production runs is 95 - 98 %. If the dead time appears to be systematically smaller (on the level of 80 %) experts should be called.


Rate Troubleshooting

If the trigger rate is significantly different from that listed in the table (by more than 20 %).

  1. Check the PS rate. If it appears to be smaller than expected, the beam may not be tuned properly resulting in a small collimation efficiency. Check beam positions at the active collimator and BPMs (see numbers written on the white board), call MCC.
  2. Check DAQ.

Table: Expert personnel for the Level 1 Trigger
Name Extension Date of qualification
Alexander Somov 383-3446 JLab: 5553 June 20, 2015