position resolution for the cms barrel pixel detector ... · pdf fileposition resolution for...

Position resolution for the CMS Barrel Pixel Detector after irradiation

Enver Alagoz, IPRD08, 1-4 October 2008, Siena, Italy

Enver Alagöz

on behalf of CMS Pixel Testbeam collaboration

11th Topical Seminar on Innovative Particle and Radiation Detectors(IPRD08) 1 - 4 October 2008 Siena, Italy

Enver Alagoz, IPRD08, 1-4 October 2008, Siena, Italy 2

• 3-D Tracking with 66 M pixels

• Barrel layers at radii: 4.4 cm, 7.3 cm and 10.2 cm

• Pixel cell size: 100x150 μm2

• Pixel sensor thickness: 285 μm

• ~ 1 m2 Silicon in 3.8T fieldpixel module

The CMS Pixel Detector


Motivations

•At the innermost CMS pixel barrel layer, radiation exposure expected to be 3x1014 neq/cm2/year at the full LHC luminosity (1034 cm-2 s-1)

•For the first time the CMS pixel barrel sensors with the final dimensions (100x150x285 µm3) and the final readout chip were tested in magnetic field.

•Charge collection

•Leakage current and damage rate

•Hit reconstruction algorithm and eta correction

•Analysis procedure

•Position resolution3


Experimental Setup

• Telescope fully equipped with unirradiated pixel sensors• new PCB for the irradiated samples• Two peltier cooling elements and chiller• Nitrogen gas flushed into the cooling box• 2x6 mm PIN diode trigger

4

beam

Trig

ger

Telescope ROCsTelescope ROCs

DUT

Cool

ing

box

ROC - read-out chip DUT - detector under test

9>F4/(',K>(8&,@#('&590"#?)3# L&45K#M#NO#F4/F4,K&(>5)/#8'#64)7


Coordinates

!"#$%&'(%&)#*+,&"#-./&(%0#1 2&345#64)7#84989#)8#:;<#6=8)> ?448&,@<#A(8'64/#BC8%<#;CCD D

E48>F#)8#:;#64)7#5&,4E48>F#)8#:;#64)7#5&,4

G4)7H#BIC#J4! F&',9 *97)55#7>58&F54#9()884/&,@0<#;I,9#98/>(8>/4

?)@,48H#?B#*;#9>F4/(',K>(8&,@#('&590"#?)3#L&45K#M#NO#F4/F4,K&(>5)/#8'#64)7

$PQR#2/4S499&, 9&84

:;#)/4)

NO#E>F4/(',K>(8&,@#7)@,48

64)7H

BIC#J4! ! G#L&45K

64)7

G#L&45K

P#L&45K

• Beam line: CERN H2 beam area• 150 GeV π- with 25 ns bunch structure• Helmholtz superconductor coils (max 3T)

5

Verti

cal C

oord

.

Horizontal Coord.


Bias Voltage [V]

100 150 200 250 300

Ch

arg

e [

MP

V /

10

00

ele

ctr

on

s]

22

22.5

23

23.5

24

24.5

25

25.5

26

26.5

Charge Collection vs Bias

new sensor - total cluster charge

6


Charge Collection vs Fluence

Bias Voltage [V]100 150 200 250 300 350 400 450 500

Ch

arg

e [

MP

V/1

000

ele

ctr

on

s]

15

20

25

30new sensor

-2 cmeq n14 10! = 0.8 "

-2 cmeq n14 10! = 2.2 "

-2 cmeq n14 10! = 6.2 "

-2 cmeq n14 10! = 8.2 "

total cluster charge vs irradiation


Leakage Current vs Fluence

]-2 cmeq

Fluence [n0 0.2 0.4 0.6 0.8

1510!

Leakag

e C

urr

en

t [A

]

0

5

10

15

20

25

30

-610!

Leakage currents (Ileakage) - at 200V - at 263 K

8

Ileakage ! !


Leakage Current Damage Rate

]-2 cmeq

Fluence [n0 0.2 0.4 0.6 0.8

1510!

]-1

[A

cm

"

0

10

20

30

40

50-18

10!

9

RD48 (ROSE)

![Acm!1] =Ileakage[A]

Volume[cm3] · ![neqcm!2]

! = (3.99± 0.03)! 10!17Acm!1

independent of fluence as expected


Vertical Coordinate

Hit Reconstruction

10

xcenter

xhit

Winner

Wx

T1/2

qfirst

qlast

L

xhit = xcenter +qlast ! qfirst

qlast + qfirst|LorentzShift|! 1

2LorentzShift

• Pitch is 100 µm• No rotation α = 0• T is thickness

• Lorentz Shift = T x tan(θL)• Wx = T x tan(α) + Lorentz Shift

•This algorithm is used only for the unirradiated sensor


Analysis procedure

Cuts:1) Cluster charge < 50000 electrons2) Fiducial cut3) One hit per ROC per event4) Cluster of size 2 pixel for the telescope ROCs5) Cut on the correlation offset

Alignment:7) Least-square fit to 4 points in telescope and extrapolate the prediction from the fit8) Get residuals for the test sensors

11

!total =!

!2telescope + !2

DUT


Position resolution

χ2

Prob(χ2, 2)

- new sensor - 200V bias- 3T- two pixels- pitch 100 µm

12

Residual [mm]-0.1 -0.05 0 0.05 0.1

0

50

100

150

200 !total ! 9µm


Eta correction

Xhit = XL + F(!) · pitch

F(!) =

! eta!1 "(!)d!

! 1!1 "(!)d!


Position resolution

Residual [mm]-0.1 -0.05 0 0.05 0.1

0

100

200

300 !total ! 10µm - 200V- 3T- two pixels- pitch 100 µm

! = 0.87! 1014neqcm!2


Position resolution

Residual [mm]-0.1 -0.05 0 0.05 0.1

0

50

100

150

200

250

300 - 300V- 3T- two pixels- pitch 100 µm

!total ! 8.5µm

! = 2.2! 1014neqcm!2


Summary

•The CMS pixel barrel sensors with the final dimensions and the final readout chip were tested in magnetic field.

•Charge collection decreases with irradiation and can be increased by applying higher biases

•Leakage currents were measured and damage rate α ≈ α (RD48)

•Hit reconstruction algorithm is used for the unirradiated and eta correction for the irradiated pixels.

•Alignment and tracking has been done

•Residual sigma for the cluster of size 2 pixels at different Vbias:

9 µm (new), 10 µm (0.87x1014 neq cm-2) and 8.5 µm (2.2x1014 neq cm-2)


E. Alagöz1,2 , V. Chiochia1 , T. Rommerskirchen1 , J. Rochet1

S. Dambach2,3 , C. Eggel2,3 , U. Langenegger2 , P. Trüb2,3 , A. Starodumov3

T. Rohe3 , D. Kotlinski3 , B. Meier3, W. Erdmann3

M. Swartz4

1Physik Institut der Universität Zürich (CH), 2 Paul Scherrer Institut (CH), 3 ETH Zürich (CH), 4 Johns Hopkins University (USA)

CMS Pixel Testbeam Collaboration


BACKUP SLIDES

18


Readout

Analog signal from 5 ROCs

Motherboard for module testing (PSI/ETH)program & readout ROCs,embedded 12-bit ADC,64 MB memory buffer

TBM

Data out (USB)

19


Correlation

! = new sensor : Vbias = 150V : B = 3Tirradiated roc

telescope rocs

20


Pulse Height Calibration

• PHCalibration Fit function

• 6 Parameters

TS(new) !B = 0 VBias = 150V

Tan (par[0] · ADC) + par[1] · (ADC)3 + par[4] · (ADC)2 + par[2] · ADC + par[3]

21



22

Bias Voltage [V]

100 150 200 250 300 350 400 450 500

Ch

arg

e [

MP

V / 1

000 e

lectr

on

s]

6

7

8

9

10

11

12

13

14

Irradiated sensor - total cluster charge 8.2 x 1014 neq cm-2


Hit Maps

! = new sensor : Vbias = 150V : B = 3T

Pixe

l Row

s (10

0 µm

)

Pixel Columns (150 µm)

Nev

ents

/pi

xel

23



Bias = 75VEntries 1822383

Mean 28.15

RMS 11.48

/ ndf 2! 1.655e+04 / 70

Width 0.004± 1.642

MP 0.01± 22.29

Area 1378± 1.827e+06

GSigma 0.007± 3.833

Total cluster charge [1000 electrons]

0 10 20 30 40 50 60 70 80 90 100

En

trie

s

0

0.02

0.04

0.06

0.08

0.1

0.12

610"


Mean 28.15

RMS 11.48

/ ndf 2! 1.655e+04 / 70

Width 0.004± 1.642

MP 0.01± 22.29

Area 1378± 1.827e+06

GSigma 0.007± 3.833


Mean 29.41

RMS 11.5

/ ndf 2! 8349 / 74

Width 0.004± 1.739

MP 0.01± 23.33

Area 1350± 1.754e+06

GSigma 0.007± 3.376


0 10 20 30 40 50 60 70 80 90 100

En

trie

s

0

0.02

0.04

0.06

0.08

0.1

0.12

610"


Mean 29.41

RMS 11.5

/ ndf 2! 8349 / 74

Width 0.004± 1.739

MP 0.01± 23.33

Area 1350± 1.754e+06

GSigma 0.007± 3.376


Mean 31.4

RMS 11.57

/ ndf 2! 4674 / 80

Width 0.005± 1.929

MP 0.01± 25.06

Area 923± 8.196e+05

GSigma 0.010± 2.811


0 10 20 30 40 50 60 70 80 90 100

En

trie

s

0

10

20

30

40

50

603

10"


Mean 31.4

RMS 11.57

/ ndf 2! 4674 / 80

Width 0.005± 1.929

MP 0.01± 25.06

Area 923± 8.196e+05

GSigma 0.010± 2.811


Mean 32.13

RMS 11.55

/ ndf 2! 1.057e+04 / 82

Width 0.004± 1.964

MP 0.01± 25.78

Area 1278± 1.577e+06

GSigma 0.008± 2.822


0 10 20 30 40 50 60 70 80 90 100

En

trie

s

0

20

40

60

80

100

310"


Mean 32.13

RMS 11.55

/ ndf 2! 1.057e+04 / 82

Width 0.004± 1.964

MP 0.01± 25.78

Area 1278± 1.577e+06

GSigma 0.008± 2.822


Mean 32.17

RMS 11.37

/ ndf 2! 4885 / 83

Width 0.006± 1.893

MP 0.01± 26.01

Area 716± 4.945e+05

GSigma 0.013± 2.516


0 10 20 30 40 50 60 70 80 90 100

En

trie

s

0

5

10

15

20

25

30

35

310"


Mean 32.17

RMS 11.37

/ ndf 2! 4885 / 83

Width 0.006± 1.893

MP 0.01± 26.01

Area 716± 4.945e+05

GSigma 0.013± 2.516


Mean 32.36

RMS 11.27

/ ndf 2! 4335 / 83

Width 0.006± 1.894

MP 0.01± 26.22

Area 717± 4.966e+05

GSigma 0.013± 2.525


0 10 20 30 40 50 60 70 80 90 100

En

trie

s

0

5

10

15

20

25

30

35

310"


Mean 32.36

RMS 11.27

/ ndf 2! 4335 / 83

Width 0.006± 1.894

MP 0.01± 26.22

Area 717± 4.966e+05

GSigma 0.013± 2.525

Landau+Gaussian fit to total cluster charge

24

position resolution for the cms barrel pixel detector ... · pdf fileposition resolution for...

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