Status report of the L2Cal upgrade for the L2Cal team Chicago, Fermilab, Madrid, Padova, Penn, Pisa, Purdue

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Status report of theL2Cal upgradefor the L2Cal
team Chicago, Fermilab, Madrid, Padova, Penn,
Pisa, Purdue
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Motivation

• Observe large increase of jet/met based trigger
  cross sections
• Reach limit of available bandwidth
• Efficiency of multi-jet triggers decreases
• Cause ?
• (True/fake) jets merged together
• Low ET jets promoted to high ET jets
• Multi-jet events ? single jet events
• Temporary solution
• PS or DPS
• Long term solution
• Modification of the L2 calorimeter trigger

Project approved on September 14th 2006 As vital
for preserving and improving the sensitivity for
Higgs searches
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System Overview

• Current Pacman
• uses 8-bit resolution for tower energies
• finds a seed (gt 3 GeV) from lowest ??
• attaches any shoulder (gt 1 GeV)
• defines cluster centroid as lowest ??
• How can we improve ?
• Calorimeter trigger tower information available
  to the L2 Decision with 10 bit resolution
• New algorithm in L2 CPU
• Jet clustering (cone based)
• Met calculation
• Install parallel L2CAL hardware path
• to be tested in fully parasitic mode

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Hardware Configuration
Muon XTRP L1 SVT XCES
Global L2 Decision
New Hardware path

• Set of Pulsar boards to
• receive,
• preprocess
• merge
• send to L2 decision CPU

8-bits
10-bits
Calorimeter
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Pulsar Setup

• SERIALIZER
• Filar boards are interface between SLINK and PC

• RECEIVERS
• Mezzanine cards are interface with LVDS cable

7 ?s (132 towers X2)
144 cables
Pulsar Merger
144 cables
12 ?s (312 towers)
SLINK 32-bit _at_ 40 MHz
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Clustering Software

• Ouline of clustering
• Orders trigger towers in ET (using min ET 0.125
  GeV)
• Cluster ET in code around the seed ET gt ET,MIN
  GeV ( ?R 0.7)
• Flag towers as used
• Sort clusters in ET (max 20)
• Cluster ? and ? are weighted by ET

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Clustering Pass
Pass 0 Seed 2 GeV
Pass 0 Shoulder 1 GeV
Pass 0 One tower per cluster One tower per cluster
Pass 1 Seed 8 GeV
Pass 1 Shoulder 7.5 GeV
Pass 2 Seed 3 GeV
Pass 2 Shoulder 1 GeV
Pass 4 (alpha) Seed From Pass 1 Had/Em lt 0.125
Pass 4 (alpha) Energy from Pass 0 Had/Em lt 0.125 Central 1? wedge ?1 ? wedge Plug 3 x 3 box No crossing in ? Energy from Pass 0 Had/Em lt 0.125 Central 1? wedge ?1 ? wedge Plug 3 x 3 box No crossing in ?

• New Clustering Algorithm
• Pass 0 not changed
• Pass 1 replaced by Pass 4
• Pass 2 cone based NEW
• Pass 4 not changed
• New Isolation Algorithm
• Starts from the seed position
• Finds iso 3x3 and (4)3x4
• Uses the smallest of the 5 sums
• Calculated for Pass 1

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FER Monitoring put

• Modification of the FER code
• Needed for backward compatibility
• Energy of towers retrieved from Dirac and print
  out in TC2D format
• New temporary bank TUPD
• Will replace the TC2D from DCAS when DCAS removed
• Monitoring of the cable occupancy and real E vs
  simulated one

G.Cortiana
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Timing performances
?t between L1A and the arrival of first fragment
to the L2TS

• Optimization
• Hardware
• Pulsar setup
• Data volume reduced by sending 3 20-bit towers in
  2 32-bit words
• Exploit LUT for tower position
• Other possibilities, zero suppression
• Software
• New PCs (2-dual core AMD opteron processors
  Gentoo 2006.1 gcc 4.1.1)
• Threaded software
• Clustering 5 ?s (on demand)

D.Krop
Low luminosity data Unbiased (previous) events
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Commissioning

• Hardware
• All in place and tested
• Interface Software
• Code for decision interface, finalized
• ready to build trigger tables for L2Cal
• Clustering Software
• Finalized
• FER Monitoring
• Almost finalized
• System successfully run in parasitic mode
• at the end of store and in between stores
• Next, compare decision between main and upgraded
  system
• (Pass 0 and Pass 4 expected to be identical)

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Summary

• The L2Cal upgrade is close to completion
• (scheduled by end of May)
• Cone based clustering is performed at L2
• MET is calculated with 10 bit full resolution
• With the new L2 Calorimeter,
• better estimate of MET
• better estimate of the cluster E location
• improve efficiency ? improve acceptance
• rate reduction in jet/met based trigger
• Could implement dijet mass cut, angular cuts, SVT
  matching, isolation, etc.

M.Schmidt