High Energy Beam Test and Simulation of

Silicon-Tungsten Calorimeter Test Module

Shinwoo Nam (Ewha Womans University)

On behalf of Ewha Womans University: S.J. Baek, H.J. Hyun, S. Nam, I.H. Park, J. Yang Korea University: J.S. Kang, S.K. Park, J.H. ChoiKyungpook National University: Y.D. Oh, K.H. Han, D.H. Kim, J.S. Seo, U.C. YangSungkyunkwan University: I.T. Yu, Y.P. YuYonsei University: B.S. Jang, S.H. Jeong, J.H. Kang, Y.J. Kwon

Introduction

• Previous studies have shown that the precision level of jet measurement required for ILC physics can be achieved by reconstructing all single particle showers in a jet.

• This leads us to two requirements for calorimeter : small Moliere radius and fine granularity.

• Silicon-Tungsten Calorimeter is a natural candidate of EM calorimeter meeting the conditions.

Content

• Development of Silicon Sensor

• Electronics and Mechanics of Test Module

• MC Simulation • Beam Test Result

• Summary

Silicon Sensor (Pixellated PIN Diode)

•Fabricated on 380um 5’ wafer

•A Sensor Size : 6.52*5.82 cm2 (including 3 guard rings )

•Pixel array : 4*4 matrix

1.55 * 1.37 cm2 each

• DC coupled

•Full depletion voltage : 90V

•Leakage current level : about 3 nA per pixel at full depletion voltage

3 Guard Rings

60um

20umN-type silicon wafer of 5 ㏀

SiO2

p+

Al

Guard Ring Pixels(Signal)

380㎛

Sawing / attach Kapton tape

Kapton tape has patterned Cu wiring(50um) on it for readout

Wire bonding

For wire boning to the diode pixel, Al wire with diameter 25 um was used. Recently we added one more wire to reduce risk of bonding failure

Glob Top (DCE, DP100)For protection of bonded wire. It is important to put the glob top in Vacuum to remove the air bubbles in glue.

Wafer -> Fabricated PIN diode matrix

Mass Production Fabrication made at SENS Technology (www.senstechnology.co.kr)

Process of Silicon Fab, Sawing, Bonding

Clean wafer

Oxidation

Cover with photoresist

Expose through maskDevelop

Etch, Stip

N+Diffusion

P+ ImplantationAnnealMetallization

Fabrication process

Capacitance Measurement

CV

0.00E+00

2.00E+17

4.00E+17

6.00E+17

8.00E+17

1.00E+18

1.20E+18

10 20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

Reverse bias voltage (V)

Cap

acita

nce(

F)

ED3_10_all

ED3_11_all

ED3_12_all

ED3_13_all

ED3_14_all

ED3_17_all

ED3_19_all

ED3_2_all

ED3_20_all

Full depletion voltage for 5kOhm wafer sensor: about 85-90V

Applied 100V because of variation in the thickness and resistivity of wafers

1/c2

Leakage Current Measurement

IV

1.00E- 10

1.00E- 09

1.00E- 08

1.00E- 07

10 20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

Reverse bias voltage(V)

Leak

age

curren

t(A)

ED2_4_1

ED2_4_2

ED2_4_3

ED2_4_4

ED2_4_5

ED2_4_6

ED2_4_7

ED2_4_8

ED2_4_9

ED2_4_10

ED2_4_11

ED2_4_12

ED2_4_13

ED2_4_14

ED2_4_15

ED2_4_16

~3nA per pixcel at full depletion voltage !

Close to 90% yield with quality cut of 20nA/pixel at 100V !

(10nA)

Dark box

Pb Pb

Photodiode sensor

Beta (90Sr) source

Gate GeneratorShaping AMP

Discriminator Trigger Photodiode

PreAmp

PreAmp for sensor

S/N ~ 120

S/N Ratio Measurement with Sr-90 source(use of single channel very low noise preamp)

Frontend Readout with CR1.4 chip

•Developed for the Pamela Experiment•16 channels of charge inputs (integrating the charge pulses -> DC levels)

•Gain: 1mV/fC•Dynamic Range: to 4000 MIPs

•up to 150 pF capacitance with leakage currents as high as 100 nA. It measures charge from 2.2 fC to 9 pC.

•Noise ~ 5000 e•Power: 0.3 mW/ch•The outputs of the T/H circuits are multiplexed to a common output buffer that is capable of driving a load of 1k and 100 pF.

•The output of the chip swings from -3V to 4V

CR1.4 chip handles a 16-ch Si sensor

Frontend board with 7 CR chips

MUX

V to C

CSA

Cf

AdjustableReset

AdjustableMOS Resister

Cfs

Cc Ct/ h

SelfTrigger

Gain

OutputBuffer

CalibrationMUX

SAT/ H

16 pixels

ADC

Gain Linearity TestUsing charge calibrationFunction of chip

Digital Electronics : ADC, Control, Power Board

FPGA

ACP Board

Power Control

DC Voltage

High Voltage

ADCs

ADC: MAX 1133

•Sampling Speed : 200ksps

(200ksps X 16bit = 0.4Mbyte/s)

•Resolution : 16bit (65536 Levels)

DAQboard

PCFrontend Board

readout speed : 0.1 msec for full readoutADC : 16 bits

Total 640 readout channels

ADC, Control Board

Data IO, Command, Calibration Boards

Integration Test of Electronics and DAQ

thickness : 3.5 mm (= 1 X0)Size 65.5 mm X 57.5 mm ( ~ sensor size)

Tungsten and Mechanics

Tungsten

Aluminum Support of a Layer

Frontend boardMount holes

Test Module : 20 layers stacked

Thickness of an Assembled Layer

Connector 2.7 mm Capacitor 1.4 mmPcb 1.7 mm Resistor 0.65 mmDiode 1.15 mm CR 1.4 chip 2.45 mmShielding board 1mm

Tungsten 3.5 mm

Aluminum 1.5 mmSensor and Readout 10 mm

15 mm

1mm inactive gap between sensors

131mm X 115mm Frontend Board

Silicon Sensor 32 pixels

in a layer

Beam Direction

Layers of Si sensorsand Tungstens

Frontend readout boards

Digitaland ControlBoards

Summary of Our Test Module Geometry• Total 20 layers = 20X with uniform layer thickness• Shower sampling at 19 layers with 2 sensors each layer.• 1mm gap between sensors• Aligned beam center to the center of a

sensor

Effective RM :~ 45mm

from volume ration of material

131mm X 115mm -> insufficient transverse shower containment

No action taken for cooling the detector.Temperature level during test : ~35 to 40 deg

1mm inactive gap

RM

Geant4 Simulation

RM is about 45mm

<30GeV, e-, for 1/500 event>

Radius(mm)

E(MeV)

Geant4.7 with full official high energy physics list, Detector geometry same as real test module,Fixed beam gun without spread, Detector responses in terms of pure energy loss (no noise and digitization)

100GeV

50GeV

10GeV

Electron Longitudinal Shower Profiles

<50GeV>

Geant Simulation

<20GeV>

Fitted curve to… 18 % / √E

total energy loss in silicon layers vs. electron beam energy

GeV

MeV

GeV

dE/E vs. E

CERN Beam Test

Steps of Beam Test

1. Tune trigger time delay 2. Align detector by using movable

table under the our detector

3. MIP calibration of all channels (using hadron beam (less sprea

d) after removing all tungstens)

4. Data Run (electron 150,100,80,50,30,20,

10 GeV hadron 150 GeV muon 150 GeV)

random trigger mixed in the runs for pedestal monitor

beam

Thanks A. Malinine for the test beam line control

Beam Test : CERN SPS H2 beam line Beam Test : CERN SPS H2 beam line for a week till Sep. 7 2004 for a week till Sep. 7 2004 Beam cycle 18.0 sec with 4.8 sec spill timeBeam cycle 18.0 sec with 4.8 sec spill timebeam line focus & existing trigger scintillators beam line focus & existing trigger scintillators give beam spread of ~1 cm diametergive beam spread of ~1 cm diameter Beam focus worse in muon beamBeam focus worse in muon beam

Channel Scan for MIP calibration

an example of a sensor with all good pixels

Scanned over all 640 channels with 100 GeV hadron Beam

(no tungsten)

Pedestal :Gaussian FitMean : 5206.9Sigma : 7.2

Signal :Landau FitPeak : 5243

ADC Counts

S/N = 5.2

50 GeV Electron

50 GeV pion

150 GeV Muon

Total ADC of an event / 640

First Analysis : sum ADC counts of all channels

No rejection of dead, noisy channels, No gain calibration applied

Detector Response to Different Particles

Online Shower Profile Monitor Pedestal subtracted

Random Trigger events (total pedestal)

Detector Response to Different e- Energy Shower

Total ADC of an event / 640

150 GeV

100 GeV

80 GeV

50 GeV

30 GeV

20 GeV

10 GeV

Readout Pedestals from Random Trigger

Calorimeter CalibrationTota

l A

DC

ab

ove p

ed

esta

l /

640

Electron Energy in GeV

Straight Fit Line 1GeV <--> 4.2 * 640 ADC Counts

Linear response, No saturation

Preliminary

Energy Resolution

Electron Energy in GeV

dE /

E (%

)

Preliminary

Fit curve : 29%/√E

Geant4 simulation of this setup taking into account only shower leakage gives18%/√E.

Simulation with dead channels (~2%), noisy channels (~10%), ADC unstable(~10%) : 21%/√E.

Further analysis needed to study the influence of beam spread, insufficient gain calibration, and readout channel cross-talks.

Summary

• High-quality Silicon pixel sensors were successfully developed and produced. - the yield close to 90% (better than initial expectation)

– excellent quality, typically Id <=10nA/cm2

• Si-W Test Module was built and exposed to the high-energy beams - Obtained typical performance as an EM calorimeter in the detector responses to the different beam energy and particle type.

- Preliminary result of electron energy resolution : 28%/√E, - MC result : 18%/√E for perfect readout 21%/√E taking into account of noisy and bad channels

- Under study for the effect of gain calibration, beam spread, and cross-talks in readout electronics

• Further tests of silicon sensors with more practical integration condition is in preparation.