The CMS Preshower Detector
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The CMS Preshower Detector Overview. CERN Armenia : Yerevan Physics Institute Belarus : Minsk University Greece : N.C.S.R. Demokritos U. of Ioannina India : Bhabha Atomic Research Centre U. of Delhi Russia : JINR Dubna

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The CMS Preshower Detector Overview

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The cms preshower detector overview

The CMS Preshower Detector

Overview

CERN

Armenia : Yerevan Physics Institute

Belarus: Minsk University

Greece :N.C.S.R. Demokritos

U. of Ioannina

India :Bhabha Atomic Research Centre

U. of Delhi

Russia : JINR Dubna

Taiwan : National Central University

National Taiwan University

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

Crystal Endcaps

Crystal Barrel

The CMS Preshower Detector

Overview

Preshower endcaps

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

The ECAL Endcaps

Crystal Endcaps : Pseudorapidity 1.479 < η<3.0

138 Standard SuperCrystals (25 crystals)

14 Special SuperCrystals

3622 Crystals

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Fiducial Coverage

The fiducial coverage of SE extends from 1.653<η<2.6

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

tt

p

g

gg

The CMS Preshower Detector

Physics Goals

π0‘s from jets fake a photon from Higgs decay

π0γγ :

γγ separation in barrel : ~ cm (possible using crystal information only)

γγ separation in endcaps : ~ mm (quite poor using crystal info)

BR(H gg ) ~ 10-3for mH<150 GeV/c2

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Design Criteria

The Preshower acts as a sampling calorimeter:

Lead absorbers : initiate EM showers

Silicon sensors : act as energy sampling devices

g

g

The Absorber : 3X0(η = 1.7) 95% conv. prob.

g

  • The silicon sensors :

  • Fabrication on 4” wafers

  • Large Area : 63 mm x 63 mm

  • Thickness : 320 μm

  • Number of Strips : 32

  • Strip Capacitance ~ 42pF

  • Occupancy ~ 1%

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Detailed Structure

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Sensor Overlap

  • 1-D sensor overlapping

  • 2mm wide dead space in one direction

  • tile + ceramic + sensor+PACE micromodule

  • 4288 identical micromodules in the complete SE (both endcaps)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

Real

Schematic

Micro-module

The CMS Preshower Detector

Micromodules

1000 micromodules to be made in Greece by

Demokritos & Un. of Ioannina

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

Real

Schematic

Ladder

The CMS Preshower Detector

Ladders

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Layout

Each end cap : 4.5m2

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon Sensors Design

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon Sensors Mask

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon Sensors Parameters

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Electronics

PACE is the compination

Of 2 chips:

Delta and PACE_AM

Delta front-end +

Programmable biasing

And calibration

PACE_AM

160 column, 32 deep FIFO.

Programmable biasing, mux

40MHz clock

New Design in submicron tecnology (will be delivered for testing in May 2003)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Electronics (Submicron Technology)

Delta3.. area = 17mm2,

[Delta 2 = 21mm2]

PACEAM3.. area = 30mm2,

[PACEAM2 = 60mm2]

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon sensors measurement setup

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon sensors characteristics(1)

34 Sensors manufactured by Demokritos (Institure of Microelectronics-IMEL) while the masks were designed by INP

C-V

Half of them have beengiven to University Of Ioannina

At this point in Demokritos we have 87 sensorswithin specifications (17 fromIMEL and 70 from ELMA-Russia)

I-V

Final goal to deliver 1000 sensors to the CMS collaboration

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon sensors characteristics(2)

Depletion voltage for each strip of the 34 sensors (Volts)

Breakdown voltage for each strip of the 34 sensors (Volts)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Silicon sensors characteristics(2)

Breakdown voltage for each strip of the 34 sensors

Leakage Current at Depletion voltage for each strip of the 34 sensors (Ampers)

Leakage Current at 300V for each strip of the 34 sensors

(Ampers)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

Data

Duplication

Manager

Labview V5.1

User

Applications

Product

Managers

Virtual

Instruments

Orbix V3.0.1

Local

Center

Manager

CORBA

Instrument

Agents

Physical

Instruments

Central

Repository

Main

Database

Production

Database

Configuration

Database

Digital

Control

Panels

Objectivity V5.2

The CMS Preshower Detector

Silicon sensors

C.R.I.S.T.A.L. Local Center Software Architecture

Implemented in Windows 2000

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Expected response for single γ

A single 30 GeV pT (η = 1.7) photon on the SE and EE

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Expected response for π0

Two closely spaced photons (~1 cm) from the decay of a 30 GeV pTπ0 (η = 1.7)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Photon (coming from π0) separation in Preshower

PreShower strip = 6 cm x 2 mm

photon

=1.7

0

=2.4

Unfortunately these are not ‘typical’ events

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

π0/γ Preshower cluster energy distribution

Et=20,=1.7

Et=50,=1.7

0/

0/

Indication of separation power: Variation of Width with Et

Clearly lose separation power at higher Et (even worst at higher η)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

π0rejection algorithm

Preshower information: Energy (fraction) in 11 strips

particle

around a ‘Central’ strip

Central strip definition:

  • Extrapolate a straight line from ECAL cluster barycenter to point (0,0,0)

  • Find the intersection of this line with the two Preshower planes

  • The strip closest to the intersection point is defined as the ‘Central Strip’

Layer1 (x)

Layer2 (y)

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector neural network 0 rejection algorithm

The CMS Preshower DetectorNeural Network π0 rejection algorithm

Use Neural Network

(Feed-Forward Back-Propagation)

23 input variables: 22 PreShower + 1 ECAL crystals

‘Central’ strip: extrapolation from crystals

For each strip i in layer 1: Ei / i=1..11 Ei

For each strip i in layer 2: Ei / i=1..11 Ei

Crystal information: S1/S25

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower DetectorNeural Network output

Et=20,=1.7

Et=60,=2.4

0

0

Performance:Look for 0-rejection @ 90% -efficiency

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detectorπ0 rejection vs Et and η

CMSIM : Detector simulation based on GEANT

ORCA : Detector Reconstruction

A.Kyriakis (Preshower INP Demokritos group)


The cms preshower detector overview

The CMS Preshower Detector

Conclusions

  • Demokritos is able to manufacture high quality Silicon Sensors to be used in the CMS-Preshower project

  • A part of the sensors will be manufactured in Demokritos and the rest will be bought by ELMA- Russia and Hammamastu

  • Neural Network techniques gave good results in π0 rejection and will be soon implemented in the official CMS reconstruction Software

A.Kyriakis (Preshower INP Demokritos group)


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