New CMS Level-1 Trigger Design for the
Upcoming Data Taking
Pamela Klabbers for the CMS Collaboration
Physics Department, University of Wisconsin,
Madison, WI, USA
IRPD13
Wednesday, 9 October 2013
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 1
Large Hadron Collider (LHC) Run 2
LHC is currently improving the magnet interconnections
so that we may safely go to proton energies of 6.5 TeV
• Minimum 13 TeV p-p center of mass energies
• Second LHC run possibly another discovery run
• Additional increase in luminosity 4-8 times previous run
• 25* or 50 ns bunch spacing
• LHC will exceed the original design luminosity (~20 ev/crossing)
• A challenge to separate the interesting event from low-energy
background (Pile-Up)
Scenario
# bunches
I p (×1011 )
Emittance (µm)
L (Hz/cm 2 s)
Pile-up
L (fb−1 /year)
25 ns
25 ns
low emit
50 ns
50 ns
low emit
2760
1.15
3.5
9.2 × 1033
21
24
2320
1380
1.15
1.6
1.9
2.3
1.6 × 1034
0.9–1.7 × 1034
43
40–76
42
45
1260
1.6
1.6
2.2 × 1034
108
–
~ original design
luminosity
Heavy Ions expect lumi increase of 4-8 times previous
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 2
CMS Triggering Challenges
Original specification for CMS detector electronics was to
operate at a trigger rate of up to 100 kHz
• Some CMS detector systems would need replacement or major
upgrades to exceed this rate (e.g. tracker replacement)
• Increases in energy, luminosity, and pile-up require significantly
higher thresholds to operate with the current L1 trigger
• Need to maintain our sensitivity for electroweak physics and
TeV scale searches
• Maintain same acceptances as 2012-2013 running
• Solution is to upgrade the trigger to
• Improve resolution
• Improve efficiency
• Reduce trigger rates
• Commission in parallel to existing trigger
• Reduce the risks associated with commissioning a new system
• Validate performance, seamless switch-over when ready
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 3
L1 Trigger Upgrade Goals
• Improve e/g object isolation using calorimeter energy
distributions with Pile-Up (PU) subtraction
• Improve jet finding with PU subtraction
• Improve hadronic t ID with a smaller fiducial area
• Improve muon pT resolution
• Isolate muons using calorimeter energy distributions
with PU subtraction
• Improve global Level-1 trigger menu
• Allow greater number of triggers
• Allow more sophisticated algorithms
• Simplify the hardware to reduce costs and
maintenance requirements
• Use similar electronics as in other CMS upgrades
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 4
Hardware Upgrades
Use Modern High-Capacity FPGAs with high speed links
• 10x increase in comparison to those currently operating in CMS
Take advantage of modern mTCA technology
• Standardized hardware platform (specs at: http://www.picmg.org)
• Hot swappable, inexpensive modules, very configurable
• Point to point high-speed-serial instead of parallel VME
• Significantly more backplane bandwidth
• Not including spare I/O
• Native support for several protocols
• GbE, Serial ATA, Serial Attached SCSI, PCIe, and Serial Rapid IO
• Redundant Power Supplies, mTCA Carrier Hubs (MCHs), and cooling units
• CMS will use the 2nd MCH slot for DAQ and timing and trigger signal
distribution (custom AMC13*)
• Smaller form factor cards
New Custom Interface to Data Acquisition (DAQ) and Trigger Timing and
Control (TTC) system
• AMC13* (Advanced Mezzanine Card)
P. Klabbers, U. Wisconsin, IRPD13, October 2013
*For more details go to http://amc13.info
New CMS Level-1 Trigger - 5
Original CMS Level-1 Trigger
Calorimeter, muon, and beam monitoring (not shown) systems participate in CMS L1
Muon Trigger
Calorimeter Trigger
0<||<5
||<1.6
0.9<||<2.4
ECAL
Trigger
Primitive
s
HCAL/HF
Trigger
Primitive
s
RPC hits
CSC hits
DT hits
Link
system
Segment
finder
Segment
finder
Pattern
Comparator
Track
finder
Track
finder
40 MHz pipeline
||<3
Regional
Calorimeter
Trigger
4+4 m
Global
Calorimeter
Trigger
4m
Global Muon Trigger
||<1.2
4m
D
A
Q
4m
e, J, ET, HT, ETmiss
Global Trigger
L1A
CMS
experiment
Status
TTC system
TTS system
32 partitions
Detector Frontend
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 6
η
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
θ°
84.3°
78.6°
73.1°
67.7°
62.5°
57.5°
52.8°
48.4°
44.3°
40.4°
36.8°
η
8
MB4
ME4/2
RE3/3
RE4/3
1.7 20.7°
1.8 18.8°
2.0 15.4°
ME2/1
2.1
2.2
2.3
2.4
2.5
ME1/1
HCAL
2
ECAL
Steel
1
0
1.6 22.8°
1.9 17.0°
RE1/2
ME1/2
Solenoid magnet
3
2015
RE4/2
RB1
4
RE3/2
MB1
RE2/2
RB2
1.5 25.2°
ME4/1
MB2
5
1.4 27.7°
ME3/2
RB3
ME3/1
MB3
6
ME2/2
Wheel 2
RE2/3
Wheel 1
Wheel 0
1.3 30.5°
RE1/3
RB4
7
θ°
1.2 33.5°
DTs
CSCs
RPCs
ME1/3
R (m)
Muon Geometry
14.0°
12.6°
11.5°
10.4°
9.4°
3.0 5.7°
Silicon
tracker
4.0 2.1°
5.0 0.77°
0
1
2
P. Klabbers, U. Wisconsin, IRPD13, October 2013
3
4
5
6
7
8
9
10
11
12
z (m)
New CMS Level-1 Trigger - 7
Muon Trigger Upgrade
Currently 3 different track finders (DT, RPC, CSC)
• Send 16 muon candidates to Global Muon Trigger
• Lateral exchange of information
• CSC Muon Port Card (MPC) has a bottleneck - max 3 track seg. to track finder
Upgrade
•
•
•
•
•
New CSC MPC FPGA (on mezz) – send all 18 possible track segments
More CSCs and RPCs on Endcap (1.25 < || < 1.8)
Upgrade to ||>2.1 CSC electronics
Split chamber hits before track finders
Combine in one track finder, mTF
• Better overlap, more
tolerant of dead channels
• Fewer fake muons
• No lateral exchange
of information
• Include calo trigger
info for m-isolation
• More, higher-resolution
muons at Global Trigger
for improved isolation, invariant mass, etc.
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 8
Muon Hardware
Large modular LUT processor MTF7
• Being built for Muon Endcap upgrade but designed
to be compatible with other muon TFs
• To be used in overlap region
• Maximizes input from muon detectors
• Large capacity for RAM (~1GB) for track-finding
• Prototype with Virtex 6
• Virtex 7 design in progress
Core Module
Optical Module
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 9
CMS Calorimeter Geometry
EB, EE, HB, HE map
to 18 RCT crates
Provide e/g and jet,
t, ET triggers
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 10
Calorimeter Trigger
Commissioning in Parallel
• ECAL – Upgrade link mezzanine from Cu
to Optical (oSLB)
• HCAL – Passively split Front-End input
to Back-End (BE), keep existing BE and
upgrade to new optical BE in parallel
• HF – Upgrade all BE electronics for 2015
will have higher granularity for trigger
• RCT – Upgrade half of Recv. Mezz. to
optical (oRM) for ECAL and HF
Architecture choice – Time multiplexed
or conventional pipelined
• Time multiplexed chosen
• All calorimeter data flows through one
FPGA at full granularity
• Potentially more flexible
• Demonstrated with prototype cards
• Hardware can implement either trigger
architecture choice
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 11
Calorimeter Hardware
MMC
Power
Supplies
BE
FPGA
FE
FPGA
JTAG
USB
Interface
Rx
oSLB
2V5
3V3
Tx
Avago
Rx
1V5
1V8
2xQDR
(Bottom)
mSD
FPGA
USB
Rx
Dual SDRAM
For DAQ & TCP/IP
Avago
Tx
oRM
mC
(Bottom)
Tx
1V0
Layer-1 CTP6 (left), oSLB & oRM (center), and Layer-2 MP7 (right)
• CTP6 – Dual Virtex 6 (XC6VHX250T) FPGAs, 48 optical inputs, 12 outputs
• Virtex 6 limits link speed to 6.4 Gb/s (validated), new CTP7 with Virtex 7 allows 10 Gb/s
• For CTP7: Zynq processor running Xilinx PetaLinux for service tasks
• oSLB and oRM Mezzanine work on existing hardware – Kintex 7 FPGA
• Links validated to 4.8 Gb/s
• MP7 – Single Virtex 7 FPGA, up to 72 input & output links dep. on Virtex 7 part
• Links validated at 10 Gb/s
• Extensive Firmware and Software development
• Latest version of MP7 with XC7VX690T uses all 72 input and output links
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 12
Global Trigger
L1 Calorimeter
Trigger
L1 Muon
Trigger
Present Global Trigger
GLOBAL
TRIGGER
PROCESSOR
Trigger
Control
System
TTC
System
Detector
Front-Ends
Technical
Triggers
Remove current 128 algorithm limit
• Most of the 128 algos were used in 2012
Receive more objects
• Increase over current 12 jets, 8 electrons, 8 muons, and global
quantities
Higher resolution with increased logic
• More sophisticated correlations, e.g. invariant mass calculations
Trigger Control System merges with Trigger Timing and Control System
Utilize MP7 calorimeter processor card
• FW and SW development already under way with Virtex 6 based card
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 13
Trigger Control and Distribution
System
L1A
AMC13
Inputs
FDL
µTCA
TTClpm
TTClpm
TTCcpm
TTClpm
TTClpm
TTClpm
TTClpm
TTCcpm
TTClpm
TTClpm
µTCA
Upgraded GT
µTCA
TTC/S
redundant TTC/S
up to 12
TTS
TIM
TCS
TTCpi
TTCpi
FMM
up to 8
Existing GT
TTCpi
µTCA
TTS
TTC
TTC/S
TTS
TTC/S
Splitter
AMC13
TTCrx
TTC
UXC
USC
FED
TTCrx
TTCrx
TCDS provides clock and triggers to CMS detectors and sends and receives
control signals
Slows or stops triggers if detector buffers are full or there are errors
New system allows for more slices of detector to run in parallel, helping the
(re)commissioning of CMS
Installation during mid 2014 as part of the DAQ upgrade
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 14
Expected Performance: Muons
Barrel
Endcap
Tail clip: after pT
lookup, candidates
sent back to FPGA
and muons in 5, 10,
or 15% tails of
distributions
demoted to lower
pT.
Result: Much lower
rate for a slight
efficiency loss.
2012 High Pileup Data (~66 ev/crossing)
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 15
Expected Performance: e/g
5x Rate reduction, similar efficiency
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 16
Expected Performance: Taus
and Jets
Single Tau
Quad Jet
Current t algo based on jet trigger with large fiducial area, is useless with
high PU
Upgrade based on e/g algo with a significantly smaller fiducial area.
Jet goes from 12x12 towers square to 8x8 circular and now includes PU
subtraction, resulting significant rate reduction for multi-jet triggers
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 17
Trigger Menu
Sample Menu for
Lumi =1.1e34
• Significantly
reduced
lepton
thresholds
• Improved t
efficiency with
slightly
shallower
turn-on
• Improved
multi-jet
triggers
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 18
Higgs and SUSY Performance
Higgs
Single e/g
t & single e/g
SUSY
Multijet
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 19
Summary
This upgrade is currently under way
• With our new hardware CMS will be able to keep our thresholds
and rates low without sacrificing physics!
How will this proceed?
• Until end of 2014* - cards and splitting
• New Back End for HF
• Mezzanine cards for ECAL Back-End and Splitting for HCAL
• Mezzanine cards on existing RCT for HF and ECAL Back-End
• Mezzanine cards for Endcap Muon Track Finder
• 2015 – Commissioning in parallel
• New calorimeter trigger
• New muon trigger, using slice of DT and full CSC and RPC data
• 2016
• New Trigger ready for 2016 LHC physics run!
*end of Long Shutdown 1, currently under way
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 20
Backup
Reference:
• L1 Trigger Upgrade TDR:
• https://cds.cern.ch/record/1556311/files/CMS-TDR-012.pdf
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 21
The Large Hadron Collider
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 22
LHC p-p Collisions
Operations
2012: √s = 8 TeV
3.5 TeV Beam Energy
2808 Bunches/Beam (25 ns)
1011 Protons/Bunch
1034 cm-2 s-1 Max Inst Lumi
• Peak Instantaneous
Luminosity:
> 7.5e33?
2015: √s = 13 TeV
• Predicted Peak
Instantaneous
Luminosity:
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 23
CMS Detector
*
*Actually 3.8 T
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 24
CMS Trigger & DAQ Systems
Level-1 Trigger
• LHC beam crossing rate is 40 MHz & at full Luminosity of 1034 cm-2s-1 yields
109 collisions/s
• Reduce to ~100 kHz output to High Level Trigger and keep high-PT physics
• Pipelined at 40 MHz for dead time free operation
• Latency of only 3.2 msec for collection, decision, propagation
P. Klabbers, U. Wisconsin, IRPD13, October 2013
New CMS Level-1 Trigger - 25
e/g and Jet Algorithms
Electron (Hit Tower + Max)
• 2-tower ET + Hit tower H/E
• Hit tower 2x5-crystal strips
>90% of ET in 5x5 (Fine Grain)
Isolated Electron (3x3 Tower)
• Quiet neighbors: all towers
pass Fine Grain & H/E
• One “L” of 5 EM ET < Thr.
P. Klabbers, U. Wisconsin, IRPD13, October 2013
4x4 Tower sums from RCT to GCT
Jet or t ET
• 12x12 trig. tower ET sliding in 4x4
steps w/central 4x4 ET > others
t: isolated narrow energy deposits
• Energy spread outside t veto pattern
sets veto
• Jet  t if all 9 4x4 region t vetoes off
GCT uses tower sums for ET,MET jets for HT, MHT
New CMS Level-1 Trigger - 26
Muon Trigger
η
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
θ°
84.3°
78.6°
73.1°
67.7°
62.5°
57.5°
52.8°
48.4°
44.3°
40.4°
36.8°
MB4
ME1/2
Solenoid magnet
0
1.8 18.8°
RE4/3
RE3/3
ME4/2
2.0 15.4°
2.1
2.2
2.3
2.4
2.5
ME1/1
HCAL
2
1
1.7 20.7°
1.9 17.0°
ME2/1
3
RE4/2
RB1
4
RE3/2
MB1
RE2/2
RB2
1.5 25.2°
20151.6 22.8°
ME4/1
MB2
5
1.3 30.5°
1.4 27.7°
ME3/2
RB3
ME3/1
MB3
6
ME2/2
Wheel 2
RE2/3
Wheel 1
Wheel 0
RE1/3
RB4
7
ECAL
Steel
14.0°
12.6°
11.5°
10.4°
9.4°
3.0 5.7°
Silicon
tracker
0
θ°
1.2 33.5°
DTs
CSCs
RPCs
ME1/3
• 3 muon detectors to ||<2.4
• Drift Tubes
• Track Segment ID and
Track Finder
• Cathode Strip Chambers
• Track Segment ID and
Track Finder
• Resistive Plate Chambers
• Pattern Matching
• 4 candidates per subsystem to
Global Muon Trigger
• Global Muon Trigger sorts, removes
duplicates, 4 top candidates to
Global Trigger
• Track building at 40 MHz!
• In 2015: ME1/1 electronics upgrade
New CSC and RPC Chambers
P. Klabbers, U. Wisconsin, IRPD13, October 2013
η
8
RE1/2
R (m)
Muon Trigger
4.0 2.1°
5.0 0.77°
1
2
3
4
5
6
7
8
9
10
11
12
z (m)
New CMS Level-1 Trigger - 27
L1 Trigger Custom Hardware
RCT
(Wisc.)
GCT
(Imperial)
P. Klabbers, U. Wisconsin, IRPD13, October 2013
RPC PaC
(Warsaw)
DTTF
(Vienna)
Global Muon Trigger
&
Global Trigger
(Vienna)
CSCTF
(Florida)
• Hundreds of boards
• Thousands of:
• ASICs
• FPGAs
• Copper Cables
• Optical Fibers
• (Wo)man hours
New CMS Level-1 Trigger - 28
Calo Trigger Staging
Talk covers final version of calorimeter trigger, Stage 2
• CMS will have a Stage 1 intermediate solution to reduce rate and improve
algorithms with higher lumi in 2015
• Install inexpensive oRSC card in RCT (18 total cards – one per crate)
• Xilinx Kintex part, multiple optical outputs for GCT and new calo trigger
• Provide readout of RCT output (VME or via optical connection to new card)
• Additional processing for current calorimeter trigger
oSLB
oRM
oRSC
HCAL
Energy
HTR
ECAL
Energy
TCC
Regional
Calo Trigger
EM
Candidates
Region
Energies
Global
Calo Trigger
P. Klabbers, U. Wisconsin, IRPD13, October 2013
Copper
Optical
HCAL Optical
Splitters
HF
Energy
mHTR
HCAL
Energy
mHTR
Layer 1
Calo Trigger
CTP
Entire Summary
Layer 2
Calo Trigger
MP7
New CMS Level-1 Trigger - 29