Test-beam Results for the CMS Forward Pixel

Detector

Carsten RottDaniela Bortoletto, Gino Bolla, Amitava Roy

Purdue University28 April 2001

Test-beam Results for the

CMS Forward Pixel Detector

Carsten RottDaniela Bortoletto

Gino BollaAmitava Roy

Purdue University

28 April 2001

Pixels/blade24 Blades/disk

The CMS Detector

APS 2001 C. Rott

51018.1

Barrel + Forward Pixel Disks

FPIX-Disk

The Pixel Detector

150m x m pixelthickness 270m 22x30 pixel array

rad. hard DMILL ROCVvdepl 160

APS 2001 C. Rott

Telescope

Beam

Si-Strips vertical

Si-Strips horizontal

Scint.Counters

X/Y-Fibers1mm Dia.few mm2

Extrapolated trackx= 2.0 my= 3.6 m

Pixel Detector and Repeater Card

APS 2001 C. Rott

• 250GeV/c pion beam• Repeater card can be rotated• Can trigger on region as . small as 1mm2

Charge sharing comparison

Charge sharing between rows (rotated by 20o)

Charge sharing between rows (not rotated)

150m

150 m

APS 2001 C. Rott

LC

L

RC

R

PHPH

PH

PHPH

PH

• PH is 12bit ADC value• Charge sharing is increased by rotating the sensor• Charge sharing can be used to improve the resolution

distribution

Position correction curve

APS 2001 C. Rott

RC

R

LC

L

PHPH

PH

PHPH

PH

is the difference of the fraction of charge deposited in the neighboring pixel

)(1

)( ydyWA

P)(W

A is a normalizationfactor

vs position (20o rotation angle)

mPxx hitpixelcorr 150)(

Resolution

Resolution in micron between rows (rotated by 20o)

Resolution in micron between rows (not rotated)

APS 2001 C. Rott

Resolution

APS 2001 C. Rott

00

rotation

200

rotation

Highest resolution for large charge sharing and hits in between pixel

Signal height:

Noise:

Signal to noiseratio of 60

S/N and Efficiency

APS 2001 C. Rott

An absolute efficiency could not bemeasured because of a time stamp problem.A strong correlation between trackedposition and pixel hit position, suggestshigh efficiency.

ADCS 550

ADC3.9

Conclusions

• Charge sharing can improve the resolution• Resolution at 20

0

rotation 10-20 m• Resolution at 0

0

rotation 10-50 m• Resolution is position dependent • S/N = 60 • High efficiency

APS 2001 C. Rott

http://www.physics.purdue.edu/cdf/pixels/csem/index.htm