Trigger Glossary
- CTB
- Central Trigger Board. Piece of Electronics that receives simple inputs (primitives) from all subsystems and issues triggers based on pre-configured conditions
- Timing
- Better described as Timing and trigger distribution system. It distributes a common clock to all subsystems and is responsible for transmitting the triggers from the CTB to the other systems. It can inhibit triggers from the CTB.. It is also the system that generates the random triggers.
- trigger
- What the CTB produces and the timing system distributes. Everything else that is called that way are not really triggers, but trigger inputs, or primitives, or...
- LLT
- Low Level Triggers. These are pseudo-triggers (interesting conditions) that are matched at the subsystem level and are fed to decide on global triggers.
- HLT
- High Level Triggers. Also known as global triggers. These are the real triggers that are matched by combining inputs of several LLTs and propagated by the timing system.
- CTB data stream
- Every time a LLT or HLT is produced, a 16 byte data word is generated. These are aggregated and sent periodically to the DAQ through a TCP connection.
- Board Reader
- The artdaq software driver that communicates with the CTB. It is responsible for passing the configuration and receiving the data stream. It reformats the data sent by the CTB into a format that is then stored into the events.
- CTB software
- The software that runs on the ARM core of the CTB. It is responsible for configuring the firmware and communicating with the board reader.
CTB Trigger Definitions
For more details, here's a link to the spreadsheet where all LLT's and HLT's that are in place :
https://docs.google.com/spreadsheets/d/1d5Txk3Brd8GfNTDwR2hwk4zWlwhou1W3bB6Ku_jRAXI/edit?usp=sharing
NOTE: The trigger word sent to the DAQ by the CTB shows the state of all HLTs at a given moment. In the list below
the index of the HLT corresponds to the bit in the trigger word payload.
ID |
Payload Bit |
Description |
HLT_0 |
0 |
Random hardware trigger. Usually not used. Can be configured to fire only during beam spill. |
HLT_1 |
1 |
Beam particle trigger. No particle selection. |
HLT_2 |
2 |
Beam particle trigger with Cherenkov based particle selection. HP=1,LP=1. (Beam momentum 1-2GeV electrons) |
HLT_3 |
3 |
Beam particle trigger with Cherenkov based particle selection. HP=0,LP=1. (Beam momentum 3-5GeV pions) |
HLT_4 |
4 |
Beam particle trigger with Cherenkov based particle selection. HP=1,LP=0. |
HLT_5 |
5 |
CRT trigger, any US/DS coincidence within 240 ns. Only enabled outside the beam spill. |
HLT_6 |
6 |
CRT trigger, any US/DS coincidence within 240 ns. Onbeam *and* Offbeam |
HLT_7 |
7 |
Beam particle trigger with Cherenkov based particle selection. Excludes HP=1,LP=1. On low energy beam this is a heavy particle trigger. |
HLT_8 |
8 |
CRT trigger, Jura-side US/DS coincidence within 240 ns. |
HLT_9 |
9 |
CRT trigger, Saleve-side US/DS coincidence within 240 ns. |
HLT_10 |
10 |
CRT trigger, Jura-side US and Saleve-side DS coincidence within 240 ns. |
|
|
|
|
HLT_31 |
31 |
Random trigger. Usually not used. Can be configured to fire only outside beam spill. |
In schematic form, the assignment of HLTs to the payload of the HLT word is,
ID |
Payload Bit |
Description |
LLT_0 |
0 |
Random LLT |
LLT_1 |
1 |
Beam particle trigger. All except Sk (unavailable) and Cherenkov counters |
LLT_2 |
2 |
High Pressure Cherenkov (C713) |
LLT_3 |
3 |
Low Pressure Cherenkov (C716) |
LLT_6 |
6 |
Beam gate |
LLT_7 |
7 |
HV current limit threshold (init stream) (unused) |
LLT_8 |
8 |
Ground plane signals (unused) |
LLT_9 |
9 |
Purity Monitor (unused) |
LLT_10 |
10 |
CRT pixels around beam pipe. |
LLT_12 |
12 |
Any CRT pixel on US Saleve side |
LLT_13 |
13 |
Any CRT pixel on DS Saleve side |
LLT_15 |
15 |
Any upstream CRT pixel |
LLT_16 |
16 |
Any downstream CRT pixel |
LLT_18 |
18 |
Any CRT on US Jura side |
LLT_19 |
19 |
Any CRT on DS Jura side |
Similarly, the assignment of the LLTs to the LLT word payload is,
Central Trigger Board Cable/Fiber Connections
See the link for a spreadsheet with details of which cables/fibers are connected to which channels on the CTB.
https://docs.google.com/spreadsheets/d/1Pw-CHSCz3f0csWV3U1sOBtcS7MQ8HNQhjYQX08c-B_8/edit?usp=sharing
Central Trigger Board Data Words
See the link for a spreadsheet for details of the CTB words.
https://docs.google.com/spreadsheets/d/1CBNVBNbP6BoP0iB5_-NlLm5xxHU-mXrOYMNqeGD2FpE/edit?usp=sharing
Run Stats
Timing summaries are available on np04-srv-012 :
/log/runsummary/
The important numbers for physics data taking are
FakeTrig0 and
BeamTrig.
FakeTrig0 are fake triggers generated by the timing system for partition 0 (the standard partition for physics).
BeamTrig refers to triggers coming from the CTB.
In each case, the first column is accepted triggers, and the second column is rejected triggers.
An example:
TimeSync 5816 0
Echo 0 0
SpillStart 293 0
SpillStop 293 0
RunStart 1 0
RunStop 0 0
WibCalib 0 0
SSPCalib 0 0
FakeTrig0 10934 601
FakeTrig1 0 0
FakeTrig2 0 0
FakeTrig3 0 0
BeamTrig 1125 75
NoBeamTrig 0 0
ExtFakeTrig 0 0
CTB summaries are in
/nfs/sw/trigger/counters
Good Part is the total number of particles identified by the beam instrumentation trigger.
The HLT numbers refer to the number of each HLT trigger that has been accepted. In this case, 280 triggers have been accepted with HLT 7 ( with Cherenkov cuts) out of a total of 871 if only the basic Beam Trigger was used.
Example:
Good Part 871
Total HLT 280
HLT 0 0
HLT 1 0
HLT 2 0
HLT 3 0
HLT 4 0
HLT 5 0
HLT 6 0
HLT 7 280