1. Mini-Trigger/DAQ workshop,OCU
ECL Trigger overview
ByungGu Cheon (SKKU)
Outline
ECL calorimeter
ECL trigger scheme & performance
Recent trigger upgrade status
ECL trigger 1035 super-KEKB
Summary
Mini-Trigger/DAQ workshop,OCU

2. Belle ECL (Electromagnetic Calorimeter)
8736 CsI(Tl) crystals
g & e energy and position measurement
Trigger info. generation : powerful tool to suppress BG events.
Mini-Trigger/DAQ workshop,OCU

3. Mini-Trigger/DAQ workshop,OCU
ECL Trigger
Trigger concept/requirement
Suppress beam-BG and cosmic events
Separate physics events from Bhabha/gg
Fast trigger decision < 1.85 ms
Good timing resolution
Trigger condition
Trigger Cell (4x4 matrix) : ETC > 100MeV
Energy trigger : Total energy sum > 1GeV
Isolated cluster counting trigger : # of clusters > 3
Bhabha & cosmic-veto triggers
Mini-Trigger/DAQ workshop,OCU

4. Mini-Trigger/DAQ workshop,OCU
Trigger Cell Map
Analog cell
576 Trigger cells
ICN
136 Analog cells
 ETOT & Bhabha/gg
Physics trigger region
(Etot / ICN)
Mini-Trigger/DAQ workshop,OCU

5. Mini-Trigger/DAQ workshop,OCU
Bhabha/gg trigger
Using Back-to-Back condition of each bhabha type
depending on qLAB angle with high energy threshold.
Bhabha type
Threshold (GeV)
Type 1
5.0
Type 2
5.5
Type 3
Type 4
Type 5
Type 6
Type 7
Type 8
Type 9
Type 10
Type 11
3.0
Mini-Trigger/DAQ workshop,OCU

6. Mini-Trigger/DAQ workshop,OCU
Cosmic veto trigger
Using naive event topology of hadronic process events
against cosmic ray and beam BG topologies.
energy trigger effi.
r-f Plane in Barrel Region B A B A IR IR C D C D
Mini-Trigger/DAQ workshop,OCU

7. Mini-Trigger/DAQ workshop,OCU
Trigger Scheme
Isolated cluster counting trigger
Energy trigger and Bhabha trigger
Mini-Trigger/DAQ workshop,OCU

8. Mini-Trigger/DAQ workshop,OCU
Trigger efficiency
Energy trigger
ICN trigger
Bhaha trigger
e ~ 97%
e ~ 95%
e ~ 99%
Mini-Trigger/DAQ workshop,OCU

9. Mini-Trigger/DAQ workshop,OCU
Trigger rate tendency
ETOT>0.5GeV ETOT>1.0GeV ETOT>3.0GeV
Trigger rate : 900Hz, 400Hz, 7x1033
Mini-Trigger/DAQ workshop,OCU

10. Mini-Trigger/DAQ workshop,OCU
Trigger rate tendency
ICN bit0
ICN bit1
trigger 7x1033 :
10KHz, 1.3KHz,
55Hz, Hz
ICN bit2
ICN bit3
Mini-Trigger/DAQ workshop,OCU

11. Mini-Trigger/DAQ workshop,OCU
Trigger rate tendency
trigger 7x1033 :
350Hz, 100Hz,
10KHz, 14KHz
Bhabha
Pre-Bhabha
Cosmic
Timing
Mini-Trigger/DAQ workshop,OCU

12. Motivation for new trigger system
Weakness of Bhabha trigger for e+e-  gX event selection
Separate Bhabha and gg events in the trigger level
Expect much stable Bhabha/gg tagging than current system
Using f directional Back-to-Back condition
Tag of eegX
Matching with track trigger bits
MC simulation study
Bhabha trigger efficiency : 99%
gX trigger efficiency : 37%  72%
Mini-Trigger/DAQ workshop,OCU

13. Electronics flow chart
New trigger system
Mini-Trigger/DAQ workshop,OCU

14. Mini-Trigger/DAQ workshop,OCU
Hardware in new system
BTL
TPSD
CVC
ETM
(32)
(4)
CCM & EBM
STM
AAA
Newly added chain
GDL
Mini-Trigger/DAQ workshop,OCU

15. Mini-Trigger/DAQ workshop,OCU
Bhabha/gg tagging
r-z plane
r-f plane 5 1
Back to back for q
Back to back for f
8 overlapped sectors
Bhabha = q & f !!
For f,
8 overlapped r-f plane.
4 back to back combined signals.
4 back to back combined signals
with different threshold
For q,
16 overlapped r-z plane.
Mini-Trigger/DAQ workshop,OCU

16. Mini-Trigger/DAQ workshop,OCU
Bhabha, gg and gX
Back-to-Back
r-f plane
ECL 1 5 2 6 3 7 4 8 5 1
CDC 1 5 2 6 3 7 4 8
8 overlapped sectors
Bhabha trigger : ECL(1&5) & CDC(1&5)
gg trigger : ECL(1&5) & CDC(0&0)
Generate triggers by matching with track information !
gX trigger : ECL(1)+CDC(0) &
Bhabha/gg veto
Mini-Trigger/DAQ workshop,OCU

17. Logic simulation study5 1
&
&
TRK 1 & 5
Mini-Trigger/DAQ workshop,OCU

18. Threshold calibration
Threshold table for r-z
Threshold for r-f
( GeV ) D 1 5
3GeV
7GeV
Type 1 2 3 4 5 6 7 8 9 10 11
FWD
4.5
----
BWD
3.5
Threshold calculation ON
ON+OFF
Mini-Trigger/DAQ workshop,OCU

19. Threshold calibration
Setting of threshold for all channels
Mini-Trigger/DAQ workshop,OCU

20. Expected L1 trigger rates @ 1035 super-KEKB
Trigger bit
1035
ETOT>0.5GeV
6.5K
ETOT>1.0GeV
3.4K
ETOT>3.0GeV
2.5K
ICN bit-0
18.0K
ICN bit-1
5.0K
ICN bit-2
0.5K
ICN bit-3
0.2K
Bhabha
Pre-Bhabha
1.5K
Cosmic
38.0K
CsI timing
110.0K
Estimated with current trigger performance
Depend on super-KEKB beam condition
Some flexibility:
ETC & physics trigger region
Optimize btw trig efficiecny and trig rates
TC pulse width : 1ms
TC occupancy < 1035
Current L1 trigger system can be kept.
Mini-Trigger/DAQ workshop,OCU

21. L2/L3 trigger @ 1035 super-KEKB
It’s rather difficult to make concrete plan to prepare L2/L3 triggers
before Trigger+DAQ readout scheme is finalized.
slow
preAmp
Shaper
Flash-ADC
L2/L3 PC farm
Software triggers for ECL
ET balance
ECL/CDC matching
TC hitmap pattern
Total Energy
Cluster finding logic
fast
ECL L1 trigger
GDL
CDC L1 trigger
TOP L1 trigger
KLM L1 trigger
Mini-Trigger/DAQ workshop,OCU

22. CsI(Tl) Barrel + pure-CsI Endcap
Current trigger system should be modified to accommodate both outputs
in the trigger level.
Simple(?) concept to modify endcap electronics :
preAmp  fast shaper  STM for Barrel region
preAmp  new fast shaper  STM for endcap region
pulse height correction + active timing delay
potential problem of trigger timing resolution
Crystal 
g/cm3 X0 cm
em nm
Nph/MeV
decay
nsec
CsI(Tl)
4.51
1.86
550
52000
1000
CsI
305/400
5000
10/1000
Mini-Trigger/DAQ workshop,OCU

23. Mini-Trigger/DAQ workshop,OCU
Summary
Current ECL trigger works well and new Bhabha trigger system is in progress.
We expect the new system to be implemented before KEKB winter shutdown.
Current ECL trigger system can be used at 1035 super-KEKB.
Trigger electronics R&D work is necessary if pure-CsI is chosen to endcap calorimeter.
Mini-Trigger/DAQ workshop,OCU