Next generation of Trigger/DAQ

Snowmass2001 - P. Le Dû

Next generation of Trigger/DAQ

• Where are we today?• Evolution 2005-2010 • On/off line boundaries• What next ? 2010-2020• LC’s Triggers• Technologies• What about standards?• Technology transfer to others fields

Patrick Le Dû -


General comments about Trigger/DAQ

• From the Physics: NO loss

• From the Detector : Deadtimeless

• From the Machine : use 100%

• from T/DAQ people: maximum efficiency and minimum maintenance

Can we achieve the ultimate T/DAQ system ?


Tevatron selection scheme

Level 3

Available time (sec)

Production rate

10 10 101010 10

10

10

10

10

10

- 2

0

2

4

- 8 - 6 - 4 - 2 0 2

Hardwired processors ( FPGA)Level 1

Level 2

Recorded Events

7MHzQCD

W,Z

Top

Higgs? 396/132ns 4 µsec 20-100 sec > Sec

Standard PC’s Farm

10-50 KHz

50Hz

1 KHz

Coarse , dedicated data

RISC Processors and DSPsoptimized code

“Off-line” code

6


L2

4.2 µs

<50 Hz

D0Detector

L1 BufferPipeline) L1 Trigger

L3 Farm

MassStorage

10 KHzAccept

Acce/rej< 1KHz 100 µs latency

7.6 MHz Xing rate

48 Input nodes50 ms latency

L2 Global

PreprocessingFarm

L2 Buffer&

digitization


LHC Multilevels Selection scheme

Available time (sec)

Production rate

10 10 101010 10

10

10

10

10

10

10

- 2

0

2

4

6

8

- 8 - 6 - 4 - 2 0 2

Hardwired processors (ASIC , FPGA)

Standard processor farms& Networks

Level 1

Level 2

Level 3

# / sec

QCD

W,Z

Top

Higgs

Z’

25ns few µsec ~ms > Sec

Recorded Events

HLT


Evolution 2005-2010

• LHC (ATLAS & CMS) Two levels trigger– L1 = physics objects ( e/g,jet,m ..) using dedicated data – L2 + L3 = High Levels « software » Triggers using « digitized data »

• Complex algorithms like displaced vertices are moving downstream– CDF/DO : L2 vertex trigger – LHCb/Btev : L0/L1 b trigger

• Use as much as possible comodity products (HLT)

– No more « Physic » busses VME,PCI ..– Off the shelf technology

• Processor farms• Networks switches (ATM, GbE )

– Commonly OS and high level languages


“Logical Strategy” for event selection

Prompt Trigger “Identification of objects”

Prompt Trigger “Identification of objects”

High Level Trigger Selection “L 1 objects “ confirm

Particle signatureGlobal Topology

Trigger Menu

High Level Trigger Selection “L 1 objects “ confirm

Particle signatureGlobal Topology

Trigger Menu

Event Filter On-line processing

Event Filter On-line processing

collision rate

> KHz

> Hz

“off-line”

Coarse dedicated data

FinalDigitized dataoptimised code

Partial to full event“Off-line” code type

Local identification of• Energy cluster• Track segment• Missing energy

Objects

Classification of Physics/calibration Process

• Refine Et and Pt cut• Detector matching•Mass calculation• VTX & Impact parameters ...

• Full or partial reconstruction• Calibration & monitoring • “Hot stream” physics• “Gold platted ”events• Final formatting etc ...

Storage& analysisS1 S2 S3 S4 Sn

Few µsec

Few msec

Few sec Data streams

Logical stepsMHz

L1

L2

L3


On-off line boundaries

• Detectors are becoming more stable and less faulty• On-line processing power is increasing and use similar hw/sw

components (PC farms..)• On-line calibration and correction of data possible• More complex analysis is moving on-line

– Filter event– Sort data streams…

become flexible


Trigger strategy & Event Analysis

hoursdays

Sec. Temporary storage

•Monitoring •Calibration•Alignements

•Physics monitoring•“Gold Platted“ events• Physics samples

On-Line Processing

Database

“Garbage”Final storage

CandidatesStorage

Calibration Constant Sub-Detector performanceEvent Background Infos to the LHC

“Analysis” farm “Analysis” farm

SamplePrescale

Compress

Fast Analysis Stream Physics streams

ms

hoursdays

Sec. S1S1 S2S2 SnSn

Simple signatures

Complex signatures

Topology

Others signatures

Menu

Event Candidate & classification

Simple signatures : e/g , µ, taus ,Jet • Refine Et and Pt cut• Detector matching

Complex signatures :•Missing Et, scalar Et•Invariant and transverse mass•separation …•vertices, primary and displaced

Selection:•Thresholding•Prescaling•“Intelligent formatting “

HLT Algorithms Select« Physics tools »

Select objects and compare to Menus

HLT

Partial/Full Event Building

Reject

1-2 KHz

5-10KHz

100Hz


Summary of T/DAQ architecture evolution

• Today– Tree structure and partitions

– Processing farms at very highest levels

– Trigger and DAQ dataflow are merging

• Near future– Data and control networks centered

– Processing farm already at L2

• More complex are moving on line• Boundaries between on-line and off-line

are flexible• Comodity components more towards L1

L1 L1

L2

L3

HLT

Pass1

Pass2

Analysisfarm

Pass2

hardware

On-line

Off-line


What next ? 2010-2020

• Next generation of machines– LC (Tesla,NLC,JLC)

• Concept of « software trigger »

– VLHC : like LHC – CLIC : < ns sec collision time!– Mu collider : Not invetigated yet!

• Next generation of detectors : – Pixels trackers : ex 800 M Ch (Tesla)– Si-W calorimeters: 32 M Ch. (Tesla)

Very high luminosity > 10**34

High or continuous collision rate (< ns)

multimillion Si read-out channels

Challenges


LC beam structure

• Relatively long time between bunch trains 199 ms

• Rather long time between bunches: 337 ns

• Rather long bunch trains ( same order as detector rerad-out time: 1ms

• Relatively long time between bunch trains (same order as read-out time): 6.6 ms

• Very short time between bunches: 2.8 ns

• Rather short pulses : 238 ns

TESLA JLC (NLC)

/ / /199 ms

1ms

2820 bunches 5 Hz 150 Hz/

85 bunches

6.6 ms238 ns


LC basic trigger concept : NO hardware trigger

• Read-out and store front end digitized data of a complete bunch train into buffers – Deadtime free -- no data loss

• DAQ triggered by every train crossing– build the event and perform zero suppression and/or data

compression– full event data information of complete bunch train available

• Software selection between train : software trigger– using « off-line » algorithms

• Classify events according– physics, calibration and machine needs

• Store events : – partial or everything!


Advantages

• Flexible– fully programmable – unforeseen backgrounds and physics rates easily

accomodated– Machine people can adjust the beam using background

events

• Easy maintenance and cost effective– Commodity products : Off the shelf technology

(memory,switches, procsessors)– Commonly OS and high level languages– on-line computing ressources usable for « off-line »

• Scalable : – modular system


Consequences on detector concept

• Constraints on detector read-out technology– TESLA: Read 1ms continuously

• VTX: digitizing during pulse to keep VTX occupancy small• TPC : no active gating

– JLC/NLC : • 7 ms pulse separation

– detector read out in 5 ms– veto trains

• 3 ns bunch separation– off line bunch tagging

• Efficient/cheap read-out of million of front end channels should be developped– silicon detectors ( VTX and SiWcalorimeters)


Conclusion about LC triggers

• Software trigger concept remains the ‘ baseline ’ – T/DAQ for the LC is NOT an issue !

• Looks like the ‘ ultimate trigger ’ – satisfy everybody : no loss and fully programmable

• Feasible - (almost) today and affordable– Less demanding than LHC

• Consequence on the detector design– constraint on detectors read-out electronics (trackers)

• Consequence on the sofware environment:– on and off-line are merging : need to develop a complete

integrated computing model with common ressources from calibration, selection (algorithms and filter) and analysis /processing paths….


Technology forecast (2005-2015)Fast logic & hardware triggering (L1)

• Move to digital & programmable• ASICS not anymore developped • FPGA’s is growing and can embed complex algorithms


Technology forecast (2005-2015)(Software trigger)

• Processors and memories– Continuous increasing of the computing power

• More’s law still true until 2010! x 64• Then double every 3years

– Memory size quasi illimited !• Today: 64 Mbytes• 2004 : 256 MB• 2010 : > 1 GB

• Networks:Commercial telecom/computer standards– Multi (10-100) GBEthernet– But : Software overhead will limit the performance…

x 256 by 2016

Systematic use of : Off the Shelves comodity products


About standards

• Evolution of standards : no more HEP!– HEP : NIM (60s) CAMAC (70s), FASTBUS (80s),– Commercial OTS : VME (90s), PCI (2000) CPCI?

• Looking ahead: today commercial technologies– No wide parallel data buses in crates– Backplanes used for power distribution,serial I/O, special functions– High speeGb/s fiber & copper serial data links – Wireless data link emerging– Higher densities for micros,memories standards commercial part– Hundred of pin packages


Transfer to other fields

• Last year IEEE NSS-MIC Conference shows a great interest and a common interest

• Medical Imaging as similar requirement as us for diagnostic TEP– Large data movment and on-line treatment– Fast selection and reconstruction


Final Conclusions

• Trigger/should not be an issue for the next generation of machines like LCs

• Fully commercial OTS comodity components• Programmable & software triggers • On-line and Off-line boundaries become very

flexible: need a new « computing model »• Challenges for 2020

– Very high luminosity > 10**34

– High or continuous collision rate (< ns)

Documents

Next generation of Trigger/DAQ