siw ecal r&d in calice nigel watson birmingham university for the calice collab. motivation...

SiW ECAL R&D in SiW ECAL R&D in CALICECALICE

SiW ECAL R&D in SiW ECAL R&D in CALICECALICE

Nigel Watson

Birmingham University

For the CALICE Collab.

Motivation

CALICE Testbeam

Calibration

Response/Resolution

MAPS Option

Summary

Nigel Watson / BirminghamCLIC'08 Workshop, CERN, 15-Oct-2008 2

Motivation for Si/WMotivation for Si/WMotivation for Si/WMotivation for Si/W Shower containment in ECAL, X0 large

Small Rmoliere and X0 – compact and narrow showers

int/X0 large, EM showers early, hadronic showers late

ECAL, HCAL inside coil

Lateral separation of neutral/charged particles/’particle flow’

Strong B field suppresses large beam-related background in detector

Compact ECAL (cost of coil)

Tungsten passive absorber

~1cm2 silicon pixel readout, minimal interlayer gaps, stability Studying ~50m MAPS pixels as swap-in option, e.g in SiD, ILD,

CLICnn? CMOS process, more mainstream

Industry standard, multiple vendors (schedule, cost) (At least) as performant – ongoing studies Simpler assembly Power consumption larger – but better thermal properties


CALICE: From MC to Reality to MCCALICE: From MC to Reality to MCCALICE: From MC to Reality to MCCALICE: From MC to Reality to MC

Initial task

Build prototype calorimeters toestablish viable technologies and compare objectively

Collect hadronic shower data with unprecedented granularity• tune reconstruction algorithms• validate existing MC models

Ultimate goal

High granularity calorimeter optimised for Particle Flow measurement of multi-jet final state at the ILC (or CLIC or …)

CAlorimeter for the LInear Collider Experiment

“Imaging calorimeter”

Next task

Exploit validated models for wholedetector optimisation

Next task

Exploit validated models for wholedetector optimisation


CALICE Test Beam PrototypesCALICE Test Beam PrototypesCALICE Test Beam PrototypesCALICE Test Beam Prototypes

1x1cm2 lateral segmentation1 X0 longitudinal segment.~1 total material, ~24 X0

3x3cm2 tiles lateral segmentation~4.5 in 38 layers

5x100cm2 strips~5 in 16 layer

10 GeV pion shower @ CERN test beam

10 GeV pion shower @ CERN test beam

SiW ECALSiW ECAL Scint-Fe HCALScint-Fe HCALScint-Fe tail catcher/muon tracker

Scint-Fe tail catcher/muon tracker

beam See talk by Felix Sefkow


The 2006 CERN TestbeamThe 2006 CERN TestbeamThe 2006 CERN TestbeamThe 2006 CERN Testbeam

HCAL

Tail Catcher

ECAL

beam

SiW ECAL30x30x20cm6.4k channels(9.8k in 2008)

SiW ECAL30x30x20cm6.4k channels(9.8k in 2008)

AHCAL layer with high granular core readout

AHCAL layer with high granular core readout


ECAL Prototype OverviewECAL Prototype OverviewECAL Prototype OverviewECAL Prototype Overview

62 mm6

2 m

m

20cm

36cm

•30 layers, 3 tungsten thicknesses•Active silicon layers interleaved•Very Front End chip / readout on PCB

•W layers wrapped in carbon fibre•PCB+Si layers:8.5 mm

•6x6 1x1cm2 Si pads•Conductively glued to PCB

14 layer PCB, VFEanalogue signals DAQ


Mechanical Structure for TestBeamMechanical Structure for TestBeamMechanical Structure for TestBeamMechanical Structure for TestBeam

Differing W absorber thickness Optional indexed offsets between stacks


Production & TestingProduction & TestingProduction & TestingProduction & Testing

Mounting/gluing the wafers

Using a frame oftungsten wires

6 active silicon wafers

12 VFE chips

2 calibration switch chips

Line BuffersTo DAQ

PCB designed in LAL-Orsay, made in Korea (KNU)

60 Required for Prototype

Automation, glue : EPO-TEK® EE129-4

Glue/place ( 0.1 mm) of 270 wafers with 6×6 pads

9720 glue dots

Production line set up at LLR


Real Detector EffectsReal Detector EffectsReal Detector EffectsReal Detector Effects

Significant part of R&D is understanding which effects are important to the measurement

What details should be simulated, e.g. Non-uniformity of passive material Essential to include this level of realism in models

What can be corrected a posteriori Inter-wafer gaps (guard rings) To obtain uniform response

What has to be redesigned Guard ring scheme (“square events”)


Pedestals and Noise PerformancePedestals and Noise PerformancePedestals and Noise PerformancePedestals and Noise Performance

Residual pedestals in non-beam events after all known effects accounted for

Gaussian fits, channel-by-channel

Uniformity in pedestals Residual offset=0.2% MIP Channel-channel =

1.7±0.1% MIP Run-run = 1.1±0.4%

Noise / channel 12.9±0.1% MIP 94% channels with run-

run variation<5%

NoiseNoise

PedestalsPedestals


CalibrationCalibrationCalibrationCalibration

74 x 250k beam halo muon runs

Gaussian x Landau fits, channel-by-channel to extract calibration constant (most prob.value)

Uniformity across channels

30 GeV 30 GeV


Cross-Talk and MitigationCross-Talk and MitigationCross-Talk and MitigationCross-Talk and Mitigation

Large quantity energy deposited close to guard rings causes ~constant amplitude signal in distinct “square” pattern

Consequence of capacitative coupling between guard rings and peripheral diode pads

Simulation model supports hypothesis

By segmenting guard rings, expect reduction in effect by factor x3-30 Example of improved design

only by building prototype


Electron Event SelectionElectron Event SelectionElectron Event SelectionElectron Event Selection

Simple cuts

Based on raw energy sum

Cerenkov rejects intermediate

Rejection of pre-shower events

Beam halo on run-by-run basis

Eraw

Preliminary

+Cerenkov


Event SelectionEvent SelectionEvent SelectionEvent Selection

Data sample from CERN 2006 testbeam used in results below

Much larger samples from 2007/8 runs at CERN/FNAL

Also ±, ±, p data

Future will include combined analysis of data from individual CALICE detector subsystems

Preliminary


Inter-Wafer GapsInter-Wafer GapsInter-Wafer GapsInter-Wafer Gaps

<Eraw>

15%

20%

Response loss wider and less deep in x x layers

staggered y layers

aligned

Gaps dominated by 1mm guard rings around each 6x6 wafer

Preliminary

Preliminary

Preliminary


Inter-Wafer GapsInter-Wafer GapsInter-Wafer GapsInter-Wafer Gaps

Statistical correction for unmeasured energy in gaps (~7% area)

Response function

Smooths response Some cost in

resolution

Low energy tail in observed energy much improved

20 GeV e-PreliminaryPreliminary

Preliminary


Sampling FractionSampling FractionSampling FractionSampling Fraction

Precise detector, sensitive to even small effects

Odd-even layer asymmetry at 7% level

Arises due to small differences in passive material in addition to W absorber (PCB+glue+ Cfi+…)

7%

Beam, normal incidence

Preliminary


ECAL Hit Energy, 30 GeV eECAL Hit Energy, 30 GeV e--ECAL Hit Energy, 30 GeV eECAL Hit Energy, 30 GeV e--

Hit energy

ECAL energy/hit

Ehit/MIPs

Mean/resolution from gaussian fit, each energy

Total ECAL energy/event

Do include odd/even effects

Do not correct for gaps

Avoid by fiducial selection

Some effects not 100% understood Low energy excess (below MIP

peak)

Only minor effect on total energy

Preliminary


ECAL Longitudinal ProfileECAL Longitudinal ProfileECAL Longitudinal ProfileECAL Longitudinal ProfileS

how

er

max layer

#

Sh

ow

er

max layer

#

Beam energy / GeV

Cos(angle)

Layer # (by W depth))

En

erg

y/l

ayer/

even

t (G

eV

)

Solid: G4/MokkaDashed: data

Expected logarithmic behaviour of shower max.and angular dependence

Small deviations data/MC attributed to preshowering upstream of ECAL


Energy Response, LinearityEnergy Response, LinearityEnergy Response, LinearityEnergy Response, Linearity

Energy resolution

Emeas vs. Ebeam

Non-linearities ~1%Non-linearities ~1%

Preliminary

Preliminary

Preliminary


MAPS ECAL: Option SummaryMAPS ECAL: Option SummaryMAPS ECAL: Option SummaryMAPS ECAL: Option Summary

• How small?• EM shower core density at

500GeV is ~100/mm2

• Pixels must be<100100m2

• Our baseline is 5050m2

• Gives ~1012 pixels for ECAL – “Tera-pixel APS”

• Mandatory to integrate electronics on sensor

• How small?• EM shower core density at

500GeV is ~100/mm2

• Pixels must be<100100m2

• Our baseline is 5050m2

• Gives ~1012 pixels for ECAL – “Tera-pixel APS”

• Mandatory to integrate electronics on sensor

• Swap ~0.5x0.5 cm2 Si pads with small pixels• “Small” := at most one particle/pixel• 1-bit ADC/pixel, i.e.

Digital ECALDigital ECAL

Effect of pixel sizeEffect of pixel size

50m

100m

>1 particle/pixel

Incoming photon energy (GeV)

Weig

hte

d n

o.

pix

els

/even

t

12m


TPAC1.0 OverviewTPAC1.0 OverviewTPAC1.0 OverviewTPAC1.0 Overview

8.2 million transistors

28224 pixels; 50 m; 4 variants

Pixel: 4 diodes, Q-preamp, mask+trim

Sensitive area 79.4mm2

Four columns of logic+SRAM Logic columns serve 42 pixel “region” Hit locations & (13 bit) timestamps Local SRAM 11% deadspace for readout/logic

Data readout Slow (<5 MHz) – train buffer Current sense amplifiers Column multiplex 30 bit parallel data output

Region

“Group” (region=7 groups of 6 pixels)

Logic/SRAM columns


Beam BackgroundBeam BackgroundBeam BackgroundBeam Background

Beam-beam interaction by GUINEAPIG

LDC01sc (Mokka)

2 machine scenarios : 500 GeV baseline, 1 TeV high luminosity

purple = innermost endcap radius500 ns reset time ~ 2‰ inactive pixels

[O.Miller]

To repeat in SiD01, CLICnn,

verify optimisation

To repeat in SiD01, CLICnn,

verify optimisation

X (mm)

y (

mm

)

1TeV high lumiECAL endcap hits


Single Pixel Characterisation: Laser Single Pixel Characterisation: Laser StimulusStimulus

Single Pixel Characterisation: Laser Single Pixel Characterisation: Laser StimulusStimulus

F

B

Pixel profile

Chargecollectingdiodes

50 m

Amplitude results With/without “deep p-well” Compare

Simulations - “GDS” Measurements - “Real”


Single Pixel Characterisation: Single Pixel Characterisation: 5555Fe sourceFe sourceSingle Pixel Characterisation: Single Pixel Characterisation: 5555Fe sourceFe source

55Fe gives 5.9keV photon Deposits all energy in “point” in silicon: 1640 e−

Sometimes maximum energy deposited in a single diode without diffusion

absolute calibration!

Binary readout from pixel array Derivative of distribution to get signal peak in threshold units (TU)


MAPS OutlookMAPS OutlookMAPS OutlookMAPS Outlook

MAPS ECAL: alternative to baseline analogue SiW Multi-vendors, potential cost/performance gains New INMAPS deep p-well process (optimise charge collection) Basic physics benchmark studies (“no harm”) to evaluate

performance relative to baseline designs for future LC detectors

First Sensor, TPAC 1.0 Four sensor architecture variants on 9x9mm2 device Successful operation of highly complex pixels

See 55Fe, laser charge injection, beam particles Proved viability of the “Deep P-Well”

Revised Sensor, TPAC 1.1 – received from fab. Oct. 2008 Homogeneous 28k pixel array Pin- and form factor compatible with original sensor Full characterisation starting (~ one week) Testbeam with single particles Spring 2009

No “show stoppers”, continue concept for DECAL Will consider in any detector concept / accelerator

Future plans TPAC 2.0, full reticle size (2.5x2.5cm2) sensor Multiple layer detector, contained e.m. showers Proof of principle demonstration of digital ECAL

resolution/linearity


CALICE is developing exceptionally performant calorimetry for ILC (+CLIC+…)

Integrated approach, controlled technology evaluatation (Sefkow, Blaha) Analogue SiW – baseline technology used by SiD, ILD MAPS SiW (not this talk) scintillator ECAL, testbeam at FNAL Sept./Oct./ 08

First CALICE ECAL paper published, 2008_JINST_3_P08001 Detailed investigation of technical performance of “physics prototype” 9760 channel, 24 X0 ECAL - calibration, stability, design of DAQ, …

Large amounts of data collected at DESY/CERN SPS/FNAL MTEST 2006-2008+ Papers on transverse/longitudinal profile, technology and hadronic

model testing,… in progress

Improving on lessons learned, e.g. guard rings Developing next-generation prototypes within the EUDET framework -

realistic ECAL and HCAL modules

Use experience from modelling test beam prototypes to add appropriate realism to “whole detector” concept models Reduce uncertainties

See CALICE web for further details!

SummarySummarySummarySummary


Backup/sparesBackup/sparesBackup/sparesBackup/spares

siw ecal r&d in calice nigel watson birmingham university for the calice collab. motivation...

Documents

siw ecal rd

detector optimisation

ecal prototype overview

pcb w layers

layer pcb

hadronic showers late

daq pcb

siw shower containment