Level-1 Trigger Shift

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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:

SETUP: hd_all.tsg
CONFIG: FCAL_BCAL_PS_m9.conf (main production mode, used for the data production) or
FCAL_BCAL_PS_m10.conf (debug mode, readout raw samples for FADCs 250 and 125)


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)
FCAL + 0.5 BCAL > 0.5 GeV 1
BCAL > 1.1 GeV 3
PS 4

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

2. TS Front Pannel Triggers

Several ancillary triggers run in parallel to the main production triggers. These triggers are distributed through the TS front pannel, and are used to monitor/study detector performance. The triggers are listed below:

FCAL LED The pulser can be enabled using the FCAL css screen. FCAL team can also run an LED pulser script, which is currently not controlled through the css.
BCAL LED The pulser can be enabled using BCAL css screen. Usually the pulser script is enabled, which alternate upstream and downstream LEDs for various BCAL collumns.
Random The random trigger can be enabled from the PS css screen.

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
Random 12 100 Hz

Note, all FP trigger bits are enabled at the TS by default. If you don't see them in data or online using the trig_client monitor (see next section), check whether pulsers are enabled by looking at css screens for the FCAL, BCAL, and PS LED pulsers, see screens below. Contact with the FCAL/BCAL detector representatives.

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 the physics trigger rate (BCAL & FCAL, which is used for production) for two types of radiators: JD70-100 crystal and 4.5x10-4 X0 Aluminum. The PS trigger rate corresponds to the 75 mu thick Be converter and 5 mm collimator. Typical rates for production at small luminosity are:

Radiator Beam Current (nA) Trigger Rate (kHz)
BIT 1: (FCAL & BCAL) BIT 4: PS Total
JD70-100 150 35 - 40 3.3 - 3.6 40 - 45
4.5x10-4 X0 Aluminum 180 32 - 38 2. - 2.5 38 - 42

Rate of the main production trigger (FCAL & BCAL) as a function of the PS rate for runs with JD70-100 radiator

Fig. 1

Rate of the main production trigger (FCAL & BCAL) as a function of the PS rate for the 4.5x10-4 X0 Aluminum radiator.

  • 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