athens hep2003 a.kyriakis (preshower inp demokritos group)1 the cms preshower detector overview cern...

ATHENS HEP2003 A.Kyriakis (Preshower INP Demokritos group)

1

The CMS Preshower DetectorOverview

CERNArmenia : 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


2

Crystal BarrelCrystal Endcaps

Preshower endcaps

The CMS Preshower DetectorOverview


3

Crystal Endcaps : Pseudorapidity 1.479 < η<3.0

138 Standard SuperCrystals (25 crystals) 14 Special SuperCrystals 3622 Crystals

The CMS Preshower DetectorThe ECAL Endcaps


4

The CMS Preshower DetectorFiducial Coverage

y

z

Barrel ECAL (EB)

Endca

p E

CA

L (E

E)

n=1.

479

n=3.0n=2.6

n=1.

653

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


5

The CMS Preshower DetectorPhysics Goals

1

0.1

0.3

0.01

0.03

0.001

0.003

50 100

130GeV

150 200 250

cc

gg

Z

MH (GeV)

mW 2mZ

bb

BR( for mH<150

GeV/c2

π0 ‘s from jets fake a photon from Higgs decayπ0γγ : γγ separation in barrel : ~ cm (possible using crystal information only) γγ separation in endcaps : ~ mm (quite poor using crystal info)


6

The CMS Preshower DetectorDesign Criteria

Abso

rber

shower profile

Abso

rber

Transverse

shower profile

Transverse

The Preshower acts as a sampling calorimeter:Lead absorbers : initiate EM showersSilicon sensors : act as energy sampling devices

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

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%


7

The CMS Preshower DetectorDetailed Structure


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The CMS Preshower DetectorSensor Overlap

PACE

Silicon sensor

Ceramicsubstrate

Aluminium tile

Absorber

Motherboard

Polyimideumbilical

Cooling screen

Motherboard

• 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)


9

The CMS Preshower DetectorMicromodules

1000 micromodules to be made in Greece by

Demokritos & Un. of Ioannina

Silicon Detector

CeramicSupport

externalcomponents

PACE

Flat cable

Hybrid

BiasVoltage

AluminiumHolder

Real micromoduleused in beam tests'98, '99 & '00

Micro-module

Schematic

Real


10

The CMS Preshower DetectorLadders

Services

Al frame

Al frame

Digital electronics boardPACE

Detector

Base plate

LadderSch

emat

ic

Real


11

The CMS Preshower DetectorLayout

Each end cap : 4.5m2


12

The CMS Preshower DetectorSilicon Sensors Design

1780 μm

1800 μm

1900 μm

...

58900 (1900 x31)μm

900

μm

1945 μm

100

μm

325

μm

63000 μm

AlSiO2

p+n type Si, 300 μmn+

...

1150 μm

100

μm

100

μm

150

μm

375

μm

1780 μm

1800 μm

1900 μm

...

58900 (1900 x31)μm

900

μm

1945 μm

100

μm

325

μm

63000 μm

AlSiO2

p+n type Si, 300 μmn+

...

1150 μm

100

μm

100

μm

150

μm

375

μm


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The CMS Preshower DetectorSilicon Sensors Mask


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The CMS Preshower DetectorSilicon Sensors Parameters


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The CMS Preshower DetectorElectronics

PACE is the compinationOf 2 chips:Delta and PACE_AM

Delta front-end +Programmable biasingAnd calibration

PACE_AM160 column, 32 deep FIFO.Programmable biasing, mux

40MHz clock

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


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The CMS Preshower DetectorElectronics (Submicron Technology)

Delta3.. area = 17mm2, [Delta 2 = 21mm2]

PACEAM3.. area = 30mm2,

[PACEAM2 = 60mm2]


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LAN

GPIB

LabVIEWHost

HP 4192ACapacitance Meter

Keithley 6517HV Source &Current Meter

32 channelrelay switch board

IV & CV Measurement SetupIV & CV Measurement Setup

Barcode ReaderCRISTAL

Database Host

Serial cables

LANLAN

GPIBGPIB

LabVIEWHost







IV & CV Measurement SetupIV & CV Measurement Setup

Barcode ReaderBarcode ReaderCRISTAL

Database Host

Serial cablesSerial cables

The CMS Preshower DetectorSilicon sensors measurement setup


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The CMS Preshower DetectorSilicon sensors characteristics(1)

0.00E+00

2.00E-11

4.00E-11

6.00E-11

8.00E-11

1.00E-10

1.20E-10

1.40E-10

1.60E-10

0.00E+00 5.00E+01 1.00E+02 1.50E+02 2.00E+02 2.50E+02

Bias Voltage (in volts)

Str

ip t

o B

ackp

lan

e C

apac

itan

ce (

in f

arad

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

Half of them have been given to University Of Ioannina

At this point in Demokritos we have 87 sensors within specifications (17 from IMEL and 70 from ELMA-Russia)

0,00E+00

1,00E-09

2,00E-09

3,00E-09

4,00E-09

5,00E-09

6,00E-09

7,00E-09

8,00E-09

9,00E-09

1,00E-08

0 100 200 300 400 500 600

Bias Voltage (in volts)L

eaka

ge

Cu

rren

t (i

n a

mp

ers)

C-V

I-V

Final goal to deliver 1000 sensors to the CMS collaboration


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


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


20


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)


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

UserApplications

ProductManagers

LocalCenter

Manager

DataDuplication

Manager

InstrumentAgents

DigitalControlPanels

ConfigurationDatabase

ProductionDatabase

MainDatabase

Objectivity V5.2

VirtualInstruments

Labview V5.1

Orbix V3.0.1

CORBA

PhysicalInstruments Central

Repository

Implemented in Windows 2000

The CMS Preshower DetectorSilicon sensors


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The CMS Preshower DetectorExpected response for single γ

CMSPreshower

T

Transv erse shower

prof ile seen in the silicon strips

of the preshower

SE

EE

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


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The CMS Preshower DetectorExpected response for π0

CMSPreshower

Transverse shower

profile seen in the silicon strips

of the preshower

SE

EE

Two closely spaced photons (~1 cm) from the decay of a 30 GeV pT π0 (η = 1.7)


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The CMS Preshower DetectorPhoton (coming from π0) separation in Preshower

photon

Unfortunately these are not ‘typical’ events

PreShower strip = 6 cm x 2 mm

0

=1.7

=2.4


25

The CMS Preshower Detectorπ0/γ Preshower cluster energy distribution

Indication of separation power: Variation of Width with Et

Et=20, =1.7

Et=50, =1.7

0/ 0/

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


26

The CMS Preshower Detectorπ0 rejection algorithm

particle

Layer1 (x) Layer2 (y)

Preshower information: Energy (fraction) in 11 strips

•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’

Central strip definition:

around a ‘Central’ strip


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The CMS Preshower DetectorNeural Network π0 rejection algorithm

Use Neural Network

(Feed-Forward Back-Propagation)

23 input variables: 22 PreShower + 1 ECAL 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

‘Central’ strip: extrapolation from crystals


28

The CMS Preshower DetectorNeural Network output

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

Et=20, =1.7

Et=60, =2.4

00


29

The CMS Preshower Detectorπ0 rejection vs Et and η

CMSIM : Detector simulation based on GEANT

ORCA : Detector Reconstruction


30

The CMS Preshower DetectorConclusions

•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

athens hep2003 a.kyriakis (preshower inp demokritos group)1 the cms preshower detector overview cern...

Documents

cms preshower detectorladders

cms preshower detectorlayout

cms preshower detectorsensor

cms collaborationa

inp half

wafers large area

sampling calorimeter

identical micromodules