Level Level--1 CSC Trigger Simulation1 CSC Trigger …acosta/cms/acosta_sim_lm01.pdfdesigns (some updates needed) But we need detailed validation against real data • Testbeam and

US CMS DOE/NSF Review: May 8-10, 2001. D. Acosta, UF 1

Level-1 CSC Trigger SimulationLevelLevel--1 CSC Trigger Simulation1 CSC Trigger Simulation

Darin Acosta

University of FloridaMay 2001


Simulation StrategySimulation StrategySimulation Strategy

Studies have been carried out using the object-oriented software framework of CMS

• Geant3 for hit generation• “ORCA” for detector and trigger simulation

Entire L1 CSC Trigger scheme coded in C++• Perfect agreement achieved between simulation and

hardware for millions of events (MPC, SR, SP)Trigger rate, efficiency, and PT resolution studied

for L = 1034 cm-2s-1

• Pile-up includes 17.3 minimum bias collisions per beam crossing and neutron hits from much earlier crossings

• Aim for single muon rate <10 kHz with >90% efficiency


ORCA Production SchemeORCA Production SchemeORCA Production SchemeSignal

Zebra fileswith HITS

ORCADigitization

(merge signal and MB)

ObjectivityDatabase

HEPEVTntuples

CMSIM

HLT AlgorithmsNew

ReconstructedObjects

MC Prod.

ORCA

Prod.

HLT Grp

Databases

ORCAooHit

FormatterObjectivityDatabase

MB

ObjectivityDatabase

Catalog import

Catalog import

ObjectivityDatabaseObjectivityDatabaseytivitcejbOytivitcejbOesabataDesabataD

Mirrored D

b’s(CERN

, US, Italy,…)

Geant3

Pyt

hia

6O

RC

A


Strip FE cards

Wire FE cards

Port Card

PC

Sector Receiver

Sector Processor

OPTICAL

SR SP

CSC Muon Sorter

Global µ Trigger

DTRPC

FE

FE

Global L1

2µ / chamber

3µ / port card

3µ / sector

4µ

4µ

4µ4µ

LCT

Strip LCT + Motherboard card

Wire LCT card

In counting

house

TMB

LCT

RPC Interface Module

RIM

CSC Muon Trigger SchemeCSC Muon Trigger SchemeCSC Muon Trigger SchemeOn-Chamber Trigger Primitives

3-D Track-Finding and Measurement

Combination of all 3 Muon Systems


Geometric CoverageGeometric CoverageGeometric Coverage

ME4 descoped


CSC PT ResolutionCSC PCSC PTT ResolutionResolution

• Track segment in ME1 required to have a reasonable measurement (resolution worse than 70% otherwise)

• Track segments in three CSC stations required for optimum PT resolution and rate reduction (implemented in Sector Processor prototype)

PT < 35 GeV

1.2 < |η| < 2.0


CSC Trigger Efficiency vs. PTCSC Trigger Efficiency vs. CSC Trigger Efficiency vs. PPTT

Trigger threshold defined at 90% efficiency

Sharper turn-on for better PT resolution

Require ME1 for good PTresolution

1.2 < |η| < 2.4


CSC Trigger Efficiency vs. ηCSC Trigger Efficiency vs. CSC Trigger Efficiency vs. ηη

Significant acceptance loss when 3 stations are required and no ME4

ME4/2 ME4/1

Loose: 2 or more stations including ME1 in endcap,but any two in DT/CSCoverlap region~90% efficiency

Tight: 3 or more stations including ME1 in endcap and MB1 in DT/CSCoverlap ~70% efficiency but better PT resolution


CSC Single Muon RateCSC Single CSC Single Muon Muon RateRateWeighted minimum bias sample used to estimate rate for L = 1034

Require “tight” track conditions ( ε ≈ 70%)to get acceptable rate from standalone CSC trigger

5 kHz rate for threshold set at 25 GeV


Previous study did not include effect of punch-through or neutron hits

Had used weighted events with muons

But no significant change in rate or efficiency (< 10%) is seen when effects are included

So real muons dominate the trigger rate

CSC Rate with NeutronsCSC Rate with NeutronsCSC Rate with Neutrons


CSC Rate without ME4CSC Rate without ME4CSC Rate without ME4

Trigger rate for “loose” condition increases by ~50% if ME4 is removed because of fewer 3-station tracks ⇒ worse PT resolution

Trigger rate for “tight”condition stays about the same because 3-station tracks already required


Global Muon Trigger EfficiencyGlobal Global MuonMuon Trigger EfficiencyTrigger Efficiency

Recover some inefficiency by combining DT and CSC (loose) with the RPC muon system in an optimized way (see next slide)


Global Muon Trigger RateGlobal Global Muon Muon Trigger RateTrigger Rate

The GMT optimized algorithm gives an efficiency close to the “OR” of RPC and CSC, but a rate close to the “AND” of the two.

Optimized ⇒ RPC coincidence required in certain regions, choose lowest PT reported by RPC and DT/CSC when matched

8.1 kHz0.18%96.1%optimized

7.2 kHz0.07%89.7%AND

23 kHz1.6%97.6%OR

Rate PT>25

GhostsEfficiencyAlgorithm

Uses “loose” criteria for CSC trigger


ConclusionsConclusionsConclusionsThe previous simulations are the most detailed done to

date of the CMS muon trigger• FE amplifier response/noise is in, neutrons are in, etc.• Trigger logic mostly validated against current hardware

designs (some updates needed)

But we need detailed validation against real data• Testbeam and cosmic ray data

This requires physicist support!• Postdocs, students

It’s important to design a highly efficient L1 CSC Trigger• L2 and L3 algorithms use L1 candidates as seeds.

If L1 misses the muon, physics may be lost…• Must have ME1, and re-scoping ME4 helps at high luminosity• RPC noise/trigger rate may be unacceptably large to help GMT

Documents

Level Level--1 CSC Trigger Simulation1 CSC Trigger …acosta/cms/acosta_sim_lm01.pdfdesigns (some updates needed) But we need detailed validation against real data • Testbeam and