# Presentation: 744957

## Triggering on Particle Types: Calorimeter and Muon Based Triggers

**Sridhara Dasu**
**Department of Physics**
**University of Wisconsin-Madison**

- http://www.hep.wisc.edu/~dasu/public/DasuIEEETrg.pdf

- Many slides stolen from:
-      Sergio Cittolin, James Linnemann, and Wesley Smith

## Contents

**Calorimeter Triggers**
**Electrons, Photons, ********-leptons and Jets **
**Global energy triggers**
**Energy clustering algorithms**
**Muon Triggers**
**Pattern matching**
**Minimum ionizing signal**
**Electrons and Muons**
**Track Matching**
**Specific implementation examples**
**e+e- (BaBar)**
**e-p (ZEUS) and Fixed target () **
**p-pbar (CDF, D0, ATLAS, CMS) **
**Technologies: ASICs, FPGAs,...**
**Future**

- We will discuss the triggers by examples that I am familiar with and in the process bring out the general themes.

## e+-e- B Physics: BaBar, Belle

**Purpose of the trigger is to pass most (if not all) collision events**
**Discriminate against beam-environment collisions**

| Type | Rate (Hz) |
| --- | --- |
| Physics | 180 |
| Cosmic | 100 |
| Random | 20 |
| Beam Background | 1000-2000 |

- Hardware trigger (L1)
- Tracks + Energy
- < 2.5 kHz
- Software trigger (L3)
- ~ 100 Hz to tape
- Remove background
- Prescale Bhabhas

- 2 Level Trigger

## BaBar L1 Trigger Overview

**Calorimeter Trigger**
**N-bit pattern of energy deposits in crystals**
**Tagged by ******** angle**
**Total ********-map from 10 TPBs**
**Used in combination with the track trigger**
**Muon Trigger**
**3-bit pattern representing hit topology in the muon chambers (RPCs)**
**Used for cosmic trigger**
**Drift Chamber Trigger**
**Track stubs**
**P****T**** discrimination**
**Main trigger for BaBar**

## ZEUS QCD Physics

**ZEUS QCD Physics**

- Trigger on
- 	Electrons
- 	Jets, Missing ET
- 	Total ET

## Hadron Collider Experiments: CDF, D0, ATLAS, CMS

**B Physics (10 GeV)**
**2-5 GeV particles**
- 10 kHz (Tevatron)
**Specific Channels, ****Tracks + Separated vertices**
- 1 MHz (LHC) - Hopeless for ATLAS, CMS
**Physics at EWSB scale (250 GeV)**
**115 < M****higgs**** < 200 GeV**
**Couplings to W (80), Z (91)**
- Lepton PT ~ 40 GeV
**TeV scale supersymmetry**
- Multiple leptons, jets and LSPs (missing PT), PT < 100 GeV
**QCD Background**
**Jet E****T**** ~ 250 GeV****     Rate = 1 kHz (LHC), 0.01 Hz (Tevatron)**
**Jet fluctuations ******** electron BG**
**Decays of ********, k, B ******** muon BG**
**Technical challenges**
**7,40 MHz input ******** fast processing**
**100 Hz output ******** physics selection **

- Note: Divide by 100 for CDF,D0

## Hadron Collider L1 Trigger Challenge

**Short timescales**
**Large channel count**
**Large rate reduction**

|  | CDF,D0 | ZEUS | ATLAS,CMS |
| --- | --- | --- | --- |
| Bunch crossing (ns) | 132 (396) | 96 | 25 |
| Decision latency (s) | 4 | 5 | 2,3 |
| Channel count | 2000 | 2000 | 8000 |
| Rate reduction (kHz) | 2525 to 7,50 | 100 to 0.5 | 40000 to 100 |

**Faster, high density**
**electronics with **
**fancy algorithms**

## Overview : ZEUS

**Pipelined 3 level trigger**
**	****Level-1 (Electronics)**
**	****	****Calorimeter**
**	****	****Trackers**
**	****Level-2 (Processors)**
**	****	****Calorimeter**
**	****	****Trackers**
**	****Level-3 (Software)**
**	****	****Event Reconstruction**

## Overview : CDF Trigger

## Overview : D0 Trigger

- 128 terms

- 128 terms

- 50 Hz

- L2
- 100s

- L1/Lum
- 4.2 s

- Framework

**7 MHz input rate                               Data**

- Data Log

- 7 kHz

- 1000 Hz

-    L3
- 48+ms

- 48 nodes

## Overview : D0 Framework

## Overview : ATLAS & CMS Examples

**ATLAS**

**CMS**

## ATLAS and CMS Strategy

- Complexity handled in software on CPUs

## Theme

**Level-1:**
**	****Energy over threshold (BaBar, Belle, CDF, D0)**
**	****	****to object identification (ZEUS, CDF, D0)**
**	****	****	****to object isolation (ATLAS, CMS)**
**Level-2:**
**	****Custom processors (CDF, D0, ZEUS)**
**	****	****to full readout after Level-1 (BaBar, CMS)**

- We will talk only about Level-1 Calorimeter and Muon triggers
- More sophisticated algorithms possible at level-2,  separated vertices for B physics, etc. are discussed in other talks.

## Interaction of Particles with Matter

## Projective Geometry

**Projective geometry is important**
**ZEUS: Used complicated cable mapping and pattern searches to reduce fake rate**
**ATLAS,  CMS: Calorimeters are built projective**
**Mapping with muon system: Important for isolation**

## D0 Muon System

- 

## D0 Calorimeter Trigger

## D0 Calorimeter Trigger

## D0 Muon Trigger

## D0 Muon Trigger

## D0 Muon Trigger

## ZEUS Calorimeter Trigger Electronics

**16 Crates**
**	****Trigger Encoder Cards, Adder Cards**
**	****Identify and count objects over threshold**
**	****	****Electrons, Jets**
**	****Energy sums**
**	****	****Geometry****	**

- VME Crate
- Custom P2 & P3 bus
- ECL logic runs at 2x, i.e., 20 MHz, on TEC, Adder

## ZEUS Trigger Encoder Card

- Flash ADC EMC, HAC

- Analog input from calorimeter
- Digitize
- Characterize
- Sum
- Bussed backplane for transferring data to Adder Cards

**ZEUS ****Trigger Encoder Card**

- Discrete ECL Logic

## ZEUS Adder Card

- Object identification using pattern of energy deposition in the calorimeter.

## CDF, D0 Level 2

- CDF and D0 elected for simple level-1 but more sophisticated level-2 based on processors

## Level-2 Crate

## Level-2 Crate

## Level-2 Data Bus

## Level-2 Software

## D0 Use of Generic L2 Processors

## D0 L2 Trigger : Calorimeter Objects

## D0 Level-2 Electron

## D0 Level-2 Muon

## D0 Level-2 Global Trigger

## Calorimeter Geometry : CMS Example

**EB, EE, HB, HE map to 18 RCT crates**
**Provide e/******** and jet, ********E****T**** triggers**

## Trigger Mapping: CMS Example

## CMS ECAL Front-end Electronics

## ECAL Front-end Boards

- Serves one trigger tower     5x5 crystals

- Trigger Primitives: BCID, Energy, FG

## ECAL Frontend ASICs

- ET sum for trigger tower
- 1-bit characterizing fine-grain energy deposit profile (FG)

- One ASIC but two personalities

- Final Algorithms in ASICs       (0.25  Rad. Hard)
- Prototypes using FPGAs

- Gigabit optical to surface

- Trigger Primitives

- DAQ

- Different chips but similar output for HCAL

## Synchronization

## CMS Electron/Photon Algorithm

- Limit region of interest to minimum possible

##  / Jet Algorithm

- Reduce amount of data at each level to minimum needed

## Missing / Total ET Algorithm

- 20o

- 0o

- 40o

- 360o

- ......

- -5

- 5

- 0

- 

- 

- ET

- MET

- Strip ET sum over all 

- LUT

- For sums ET scale LSB (quantization) ~ 1 GeV is used
- = 20o used instead of HCAL tower size:  = 5o

## CMS Tower Level Memory LUT

**Fully programmable LUT, Current default values:**
** ****Electron scale: 0.5 GeV LSB, E****max****=63.5 GeV**
** ****Veto: OR of fine-grain veto and H / E < 5%**
** ****Jet / ******** scale (E+H): 1.0 GeV LSB, E****max****=511 GeV**
** ****Jet energy (12x12 tower sum), E****max****=1 TeV**
** ****Activity level for ******** pattern: E > 2 GeV, H > 4 GeV**

## 160 MHz point to point backplane (prototype tested)
18 Clock&Control (prototype tested), 126 Electron ID (prototype tested),18 Jet/Summary Cards -- all cards operate @ 160 MHz
Use 5 Custom Gate-Array 160 MHz GaAs Vitesse Digital ASICs
Phase, Adder, Boundary Scan, Electron Isolation, Sort  (manufactured)

**18 Clock&Control (prototype tested), 126 Electron ID (prototype tested),****18 Jet/Summary Cards -- all cards operate @ 160 MHz**
**Use 5 Custom Gate-Array 160 MHz GaAs Vitesse Digital ASICs**
- Phase, Adder, Boundary Scan, Electron Isolation, Sort  (manufactured)

**CMS Calorimeter Trigger Crate**

**Data from calorimeter FE on Cu links****@ 1.2 Gbaud**
***Into 126******* ******rear******Receiver******Cards***
***Prototype******tested******w/ ASICs***

- Backplane links fix the algorithm

## CMS Regional Calorimeter Trigger Prototypes

**Clock and Control Card**
**Fans out 160 MHz clock & adjusts phase to all boards**

**Clock delay adjust**

**DC-DC**
**Converters**

## 4 x 1.2 GB/s Copper Links

**Receiver ****mezzanine card **

**Test Transmit ****mezzanine card **

**Serial Link Test Cards **

**20 m 22 AWG Copper Cable, VGA Connector **

**Results:****Bit Error rate < 10****-15**** **

## Crate & Backplane

- Front

- Rear

**Std.**
**VME**
**Slots**

**Crate & Backplane**

**160 MHz with 0.4 Tbit/sec dataflow**
**Initial tests indicate good signal quality**
**Designed to incorporate algorithm changes**
**New Non-Isolated Electron, Tau & Jet Triggers**
**Many data paths checked manually and with JTAG**
**Note: we only have one RC and one EIDC for testing**
**Plan: one complete fully tested crate for slice test **

**VME Power **
**Supply**

**Custom**
**Point-to-point**
**Dataflow**

**VME**

**48V externally supplied**

**Custom**
**Point-to-point**
**Dataflow**

## CMS Receiver Card

***Top side with 1 of 8 mezzanine cards****** & 2 of 3 Adder ASICs***

**DC-DC**

**Adder**

**mezz**
**link **
**cards**

**BSCAN**
**ASICs**

**PHASE**
**ASICs**

**MLUs**

***Bottom side with all Phase******& Boundary Scan ASICs***

**Full featured final prototype board is in test - ASIC testing successful. Continue to test all data paths - develop software etc. - FY2003 program**
**Phase ASIC validated, BSCAN ASIC validated - all RC ASIC procurement now complete**

## CMS RCT : Adder ASIC

**CMS RCT : Adder ASIC**

**Key RCT technology**
**	****Fast ASICs - compact design**

## CMS Electron Isolation Card

**Full featured final prototype board is finished & under test.**
**Electron ID & Sort ASICs tested by Vitesse before delivery**
**In house testing fully validated SORT ASIC & mostly validated EISO ASIC - neighbor data requires multiple cards.**
**SORT ASIC procurement complete**
**Detailed tests of all data paths: FY2003**

## Jet-Summary Card

- SORT
- ASICs

- Recv. Mezz.

- Region 4x4 and HF sums to cluster crate.

**Jet-Summary Card**

**Being Assembled**
- Electron/photon/muon info.
- SORT ASICs to find top four electron/photons
- Threshold for muon bits
- To GCT
**Region energies**
- To cluster crate
**Absorbs HF functionality**
- Reuses Receiver Mezzanine Card
- To cluster crate

## CMS Global Calorimeter Trigger

- 1 GB/s serial inter-crate
- 3 GB/s serial backplane

- Cable backplane for flexibility

## CMS Global Calorimeter Trigger

- Generic: Common CMS, ATLAS

## CMS Muon Detectors

## CMS Muon Overview

- ASICs

- FPGAs

- ASIC to
-   FPGA

- FPGA

- FPGAs

## CMS Muon Trigger Primitives

- Memory to store patterns
- Fast logic for matching
- 	FPGAs are ideal

## CMS Muon Trigger Track Finder

- Memory to store patterns
- Fast logic for matching
- 	FPGAs are ideal

- Sort based on PT, Quality - keep loc.
- Combine at next level - match
- Sort again - Isolate?
- Top 4 highest PT and quality muons with location coord.

- Match with RPC
- 	Improve efficiency and quality

## CMS Global Trigger

## Trigger Flow : ATLAS Example

## ATLAS Calorimeter Algorithms I

## ATLAS Calorimeter Algorithms II

## Calorimeter Trigger Overview : ATLAS

**Trigger Primitives**
**Analog sum**
**Receiver**
**Quality cable plant**
**Preprocessor**
**ADC, Bunch-crossing**
**LUT, sums**
**Algorithm Implementation**
**Jets, ********E****T****, Missing E****T**
**e/********, ********/h**

- FPGA Based Generic Processors (adopted for CMS GCT)

## ATLAS Muon Trigger Detectors

## ATLAS Muon Trigger

## ATLAS Trigger Central Processor

## CMS Calorimeter Trigger Rates: 2 x 1033 cm-2 s-1

- Selected Scenario: 5 kHz e/g, 5 kHz ,jets, 1 kHz combined, rest 

- Mock
- Trigger
- Table

## CMS Calorimeter Physics Efficiency: 2 x 1033 cm-2 s-1 

- Scenario:
- 5 kHz e/,
- 5 kHz ,jets,
- 1 kHz comb,
- rest 
- No generator level cuts other than requiring trigger objects within calo. (<5) or tracker (e,) acceptance

## Improving L1 Efficiency for qqH

**Improving L1 Efficiency for qqH**

**SUSY higgs production in weak boson fusion**
**Accompanied by jets in the forward direction**
**Forward jet characteristics**
**Lower jet E****T****, but potential beam background**
**Strategy at level-1**
**Trigger on higgs decay products**
- Decays to Z (ee, ) or photons
**Low threshold electron/photon algorithm**
- Decays to 
**Narrow jet tag - developed better algorithm (2000)**
**Tag jets with location information**
- Invisible decays ()
**Missing E****T**** trigger by itself is not efficient**
**Require two tag jets also**
**Require ******** between the jets**
- Decays to b jets (dominant but dirty mode)
**Four jet trigger including forward tag jets**
**Require ******** between jets**
**Exploit that central b jets must be back-to-back**

## Global L1 Trigger Algorithms

## qqH to 2 b-jets + 2 tag jets

- b

- b

- q1

- q2

- 

**Current Level-1 Trigger**
**4 jets anywhere in the detector**
**Exploit separation of the tag jets in ******
**4 jets with ******** > 3**
**Reduce 1-jet rate to compensate for new rate**
**Rate reduction using event topology cuts**
**Rapidity gap due to lack of color connection**
**Require b-jets to be within the central detector**

| Algorithm | Efficiency for MH=110 GeV | Efficiency for MH=130 GeV |
| --- | --- | --- |
| 1, 2, 3, 4 jet triggers only | 70% | 76% |
| Additional >3 cut | 79% (+9%) | 82% (+8%) |

## High Level Trigger Strategy

## Evolution of Level-1 Triggers

**Input**
**	****Old - separate analog trigger sums + Cu cables**
**	****New - on detector ADCs++ (radiation hard ASICs)**
**               ****trigger primitives formation, **
**               ****giga-bit fiber-optic transport**
**Backplanes**
**	****Old - VME Bus, FastBus**
**	****New - Point-to-point high speed links,****           serial (1 to 3 GB/s) or parallel (160 MHz)**
**Inter-crate links**
**	****Old - Parallel differential ECL**
**	****New - Serial 1.2 GB fiber or Cu links**

## Evolution of Level-1 Triggers

**Discrete Logic**
**	****D0,CDF**
**	****	****towers over thresholds + sums**
**	****ZEUS**
**	****	****sums + pattern logic for object ID**
**ASICs**
**	****CMS RCT - ****	****object identification ****	****isolation, sorting, ****	****fast adders**
**FPGAs**
**	****Almost everywhere - ****	****Generic processors**