L1Calo Intro

Cambridge Group, Dec 2008

     

Norman Gee

Trigger strategyTrigger strategy

RoIB

High-level TriggerHigh-level Trigger

ROD RODROD

Other detectors

CalorimetersMuons

CALOtrigger

MUONStrigger

CTP

Level-1Level-1

L1A.L1A.

40 MHz40 MHz

75 kHz75 kHz<2.5 s

ROB ROBROB

Det

. re

ado

utD

AQ

Event Builder

ROS

Level-2Level-2 <40 ms

L2S

V

EFNEFN

L2A.L2A.2 kHz2 kHz

RoI requests

RoI Data

Regions of Interest (RoI)Regions of Interest (RoI)

Event FilterEvent Filter ~1 s

L2NL2N

EF Acc.EF Acc.200 Hz200 Hz

Full events

hard

ware

Soft

ware

300 Mb/s300 Mb/s

120 Gb/s120 Gb/s

3 Gb/s3 Gb/s

L1 Dedicated hardware

(ASICS & FPGAs) Calorimeters & muons Latency < 2.5 s L1A 75 kHz (Max 100kHz)

L2 ~500 dual CPUs Full granularity Regions of Interest (~2%) Latency ~40 ms L2A 2kHz

Event Filter (L3) ~1600 dual CPUs Access to full event &

calibration constants More detailed reconstruction Use Offline algorithms Latency ~1s 200Hz

2

Level-1 trigger system (L1)Level-1 trigger system (L1)

3 sub-systems3 sub-systems L1 - Calorimeters (L1Calo) L1 – Muons (L1Muon) Central Trigger Processor (CTP)

Signature identificationSignature identification e/e/, /h/h, jetsjets, Multiplicities per ET threshold

Isolation criterion Missing ET, total ET, jetE ET

Preprocessor

ClusterProcessore/e/ , /h/h

Jet/EnergyProcessor

jetsjets , EETT

MuonBarrelTrigger

MuonEndcapTrigger

Muon-CTPInterface

Central TriggerProcessor

LAr Tile RPC TGC

RoIB

L2 supervisorDetector readout

CTPCTP Receive & synchronize trigger information Generate level-1 trigger decision (L1A) Deliver L1A to other sub-detectors

3

L1 Calorimeter - ArchitectureL1 Calorimeter - Architecture

L1Calo partitioned into 3 sub-systems

Real time transmission to CTPReal time transmission to CTP

DAQ + RoIs at each L1A (DAQ + RoIs at each L1A (75kHz75kHz))

Pre-Processor (PPr) Receive & sample signal from calorimeters Coarser granularity (Trigger TowersTrigger Towers) Noise filter Bunch crossing identification (BCID) Determine final EETT value

Processors JEP & CP Physics algorithms Search for and identify:

isolated leptons, taus jets

Compute ET total, missing,…

4

5

Electromagnetic calorimeter - EndcapElectromagnetic calorimeter - Endcap

CryostatCryostat

Electromagnetic calorimeter - BarrelElectromagnetic calorimeter - Barrel

Tile CalorimeterTile CalorimeterHadronic Calorimeter – Hadronic Calorimeter – End capEnd cap

Forward CalorimeterForward Calorimeter

CalorimetersCalorimeters

Trigger towers (TT)Trigger towers (TT)

LAr Tiles (semi-projective segmentation )

trigger towers map

0.1x0.23.1 <||< 3.2

0.4x0.41253.2 <||< 4.9

0.2x0.22.5 <||< 3.1

0.1x0.1||< 2.5

x Position

Analogue summation of calorimeter cells 3584 x 2 (EM+HAD) trigger towers

6

7

.

F

R

R

F F

F F

R

TileCal trigger signals

Liquid Argon trigger signals

Receivers(64 ch.)

PreProcessor Modules(64 ch.)

PatchPanels

TileCalPatchPanels

to separatecalo and

muon signals

to convertE to ET

AnIncards

(16 ch.)Multi-chip

Modules (MCMs)(4 ch.)

CP

JEP

Mu

on

FF

D50

ADCx4

ASIC

256 16-pair cables

360

360

152 136 1120

768

128 PPMTCPP

RPPP LVDS high-speed

serial links

Overview of the trigger front-end

Long cables:• Cavern to USA15• Typically 40–70m long

• Detector responsibility

• 256 TileCal, 360 LAr

Short cables:• Internal to trigger racks• Typically 5–8m long• L1Calo responsibility• 776 in total

All analogue cables:• 16 individually shielded pairs• F/R denote front/rear of modules • All connectors D37 except TCPP

inputs, which are D50

8

Cable InstallationCable Installation

10b

Sampling 40 Mhz, Flash-ADC 10 bits 1 FADC count 250 MeV Pedestal 40 FADC counts

PP

r

Receivers (Rx) Input signal conditioning to L1 (2,5V 250GeV) Variable gain amplifier (VGA) E ET Conversion (Hadronic layers only, LAr already ET) Local signal monitoring

Pre-Processors – Energy reconstructionPre-Processors – Energy reconstruction

Transmission to processors & DAQ

10b

ET calibration Look-Up TableLook-Up Table (LUT) Pedestal subtraction, noise suppression FADCFADC (10b) GeVGeV (8b) conversion

1023

255

Ethres 8b

Bunch crossing identification (BCID) Finite impulse response filter (FIR) Peak finder (linear/saturated) Assign ET to the ‘correct’ bunch crossing

a0a1a2a3a4

+FIR

fil

ter

10

PreProcessor Module (PPM)[Heidelberg]

RAW FADC values and LUT outputs areRead out when L1A fires

Multi-chip module (MCM) with FADCs, ASIC and LVDS serialisers

Clock for FADC individually adjusted to sample on pulse peak.

Then digital data synchronised (coarse & fine adjustment) to identical times.

Towers for CP multiplexed, then serialised to 400 Mb/s and sent as LVDS

on cables to CP

For JEP, 2 x 2 em or Had towers summed, then sent at 400 MB/s to JEP

Algorithms and Regions of Interest (RoI)Algorithms and Regions of Interest (RoI)

Processor input is a matrix of tower energies Algorithms look for physics signatures (sliding window) RoI data sent to Level-2 trigger following L1A

Cluster Processor Jet/Energy-sum Processor

Criteria for e/ or /h candidate: EM or Had. cluster > Ethreshold

Total ET in EM Isolation Ring EM isolation thresh.

Total ET in Had. Isolation Ring Had. isolation thresh.

Local ET Maximum compared to neighbor windows.

e/ only: Had. core core isolation threshold

Jet candidate Coarser granularity 0.2x0.2 (jet element) Digital summation EM + Had. Sliding, overlapping windows (3 sizes)

Missing energyE

CA

L+

HC

AL

11

12

Cluster Processor Module

SerialisersCP FPGAs

Readout

Backplane Traffic

2 columns of fan-out towers to adjacent CPM on ‘left’ (-

η)

1 column of fan-out towers to adjacent CPM on ‘right’ (+η)

Backplane Fan-in/out runs at 160 Mb/s to reduce pin count Output: hit counts.

3 bits for each of 8 threshold sets, + parity. 25 e/ bits go left, 25 /h bits go right

Backplane

14

Jet-Energy module [Mainz/Stockholm]

15

Common Merger Module

Event Datato ROD

VME

TTC

Intermediate Sumson Cable Link

System CMM(Using Crate and

System Summing) Context14Jan05.cnv

Hits toCTP

CPMs orJEMs

BackplaneLinks

CrateSumming

Logic

SystemSumming

Logic

Event Datato ROD

VME

TTC

BackplaneLinks

CrateSumming

Logic

SystemSumming

Logic

Crate CMM(Using Crate

summing only)

CrateFpga

SystemFpga

TTCDecoder

G-LinkOutputs

VMEControls

VoltageRegulators

CanBusInterface

17

Central Trigger Processor (CTP)Central Trigger Processor (CTP)

ReceiveReceive, synchronizesynchronize and alignalign trigger information

Other signals: Random trigger Calibration Minimum biais events (MBTS)

Generate the level-1 trigger decision (L1A) Programmable trigger menu Latency 100 ms (4BC)

Deliver the L1A to the other sub-detectors

4 bitsJet ET

4 bitsEt total

…

6 x 3 bitsMuons

8 bitsET miss

8 x 3 bitsJets

8 x 3 bitsHadrons

8 x 3 bitsEM

# ThrInputs

256 items

RNDM1

RNDM0

…

1MU10 & 1EM15

NIM0

1J4

1TAU6

1EM1

Menu

2

1

1

1

1

1

1

1

PreScale

1

1

0

1

1

1

1

1

Mask

160 entries

L1A

18

-2

-1

0

+1

+2

Bunch crossing

Average offset from L1A timing in EM layerAverage offset from L1A timing in EM layer

19

Energy correlation with calorimetersEnergy correlation with calorimeters

HadronicElectromagnetic

L1Calo reconstructed ET vs calorimeter precision readouts

Cosmic muons Reasonable correlation achieved Very crude calibration applied, still room for improvement

L1Calo L1Calo

20

LAr EMB timing from pulser run

Coarse timing ok Focusing on fine tuning

Timing calibrationTiming calibration

Internal timing of L1Calo trigger is achieved

Input timing realized in pre-processors Not a trivial task Several strategies depending on signal

origin: calibration cosmic rays collisions

Different setup & automatic procedures Setup coarse/fine timing Ensure signals are correctly sampled (3rd sample

at maximum) Signal shape with 1 ns sampling step

21

Pedestal & NoisePedestal & Noise

Pedestals set to 40 ADC counts Sensible RMS ~ 400 MeV Nearly all channels behaving correctly

(>99%)

HadronicElectromagnetic

Mea

nR

MS

AD

C

cou

nts