pradeep ghosh 1,2 & jürgen eschke 2,3 1 goethe-universität , frankfurt am main
DESCRIPTION
Characterization of double sided silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment. Pradeep Ghosh 1,2 & Jürgen Eschke 2,3 1 Goethe-Universität , Frankfurt am Main 2 GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt - PowerPoint PPT PresentationTRANSCRIPT
Characterization of double sided Characterization of double sided silicon micro-strip sensors with a silicon micro-strip sensors with a pulsed infra-red laser system for pulsed infra-red laser system for
the CBM experimentthe CBM experiment
Pradeep Ghosh1,2 & Jürgen Eschke2,3
1Goethe-Universität, Frankfurt am Main2GSI Helmholtzzentrum für Schwerionenforschung GmbH,
Darmstadt3Facility for Antiproton and Ion Research GmbH, Darmstadt
ContentsContentsMotivationIntroductionMeasurement setupCalibration of focuserSilicon sensor under testMeasurements and resultsPlanned activities and future
work
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 2
1. Motivation1. MotivationBand gap in silicon ~ 1.1 eV and Infrared
light (1060nm) is equivalent to 1.17 eVAbsorption depth of infrared light in silicon
is around 500 µm. Silicon sensor is 300 µm thick.
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 3
Infrared light (1060nm ~ 1.17 eV) induces charge of about 24 kilo electrons and is equivalent to 1 Minimum Ionizing Particle.
Idea is to mimic in-beam scenario and investigate sensor performanceArnaud Darmont, Aphesa, white paper, 04/2009
2. Introduction2. IntroductionPulsed infrared Laser with
◦ Wavelength : 1060 nm ; Pulse duration : 10ns◦ Laser current : 41mA ; Laser Power < 5mW◦ Multi lens focuser: spot-size ~ 13 µm (1
strip/side)
◦Fully depleted CBM02 double sided strip sensor
Initial Goals◦ To create 24 kilo electrons in the sensor with the
help of LASER to mimic the MIP(~176 ADC) and observe sensor response.
◦ Focus the laser spot to fire only1 strip/side and able to scan the whole sensor with step motor.
◦ Understand the charge sharing function in the interstrip region 05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 4
3. Set up: Laser test stand3. Set up: Laser test stand
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 5
3. Set up : Laser Test 3. Set up : Laser Test Stand Stand
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 6
Focuser
CBM02 sensor
Optical fiber
Coupling: Laser and Optical fiber
Laser
Nside-nx2Nside-nx0
Pside-nx2
Pside-nx2
Laser spot
4. Calibration of Focuser4. Calibration of FocuserCalibration of the Laser
focuser was done at various heights(z-position above sensor surface) at different laser currents43mA ; 45 mA and 48 mA
Minimum number of fired strips/side was achieved at point 7 above the reference level.
Furthermore, laser can be tuned to focus to 1 strip/side firing position by reducing the laser current.
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 7
5. Sensor under test 5. Sensor under test CBM02 SPID 0-b 006 sensor non irradiatedDouble sided, 256 strips with
50µm strip pitch.Size : 1.5 cm x 1.5 cm x 300 µm1 dc pad and 4 ac pads per
stripFull depletion Voltage: 70VOperating Voltage: 100 VLeakage current at V(op): 0.5µAReadout via self triggering
nXYTER based FEE
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 8
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 9
6. Measurements with Pulsed Laser
Strip number
Num
ber
of
hit
s
Strip number
Num
ber
of
hit
s
p-side
ADC values
Num
ber
of
hit
s
Channel hits(fired strips) Channel hits(fired strips) per side per side
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 10
Digital amplitude with position Digital amplitude with position per side per side
Equal number of hits on both p and n side of the microstrip sensor Strip nr.132 on p-side and Strip nr. 122 on n-side is fired. One strip cluster on both sides of sensor proves that charge
collected only by one strip and not been shared by neighboring strips.
ADC counts suggest we are able to induce charge eqv. of 1 MIP.
n-side
ADC values
Num
ber
of
hit
s
Hit position in the Hit position in the detectordetector
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 11
Sensor Size : 1.5 x 1.5 cm2
Strip width is 18 µm; Strip pitch is 50 µm.
Laser spot size ~ 13 µmStep motor attached to the Laser
system has a pitch of few µm. Enabling to investigate the interstrip region.
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 12
18 µm
50 µm
Cha
rge
colle
cted
in A
DC
Distance from the Strip, µm0 50
1 MIP
Charge Collected at Strip 1Charge Collected at Strip 2
Charge sharing function- Charge sharing function- measurementmeasurement
The curve above is just a cartoon
Charge sharing function-Charge sharing function-resultsresultsRed and Green curves
shows the charge collected by individual strip when laser moves in the interstrip region.
Blue curve shows the charge sharing function.
Results shows a plateau region (10-12 µm) where charge is always shared equally with neighboring strip.
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 13
Preliminary result
Planned activities & future Planned activities & future workworkStrip-by-strip characterization of silicon
sensors by scanning over it.Preparing and pre-testing prototype
sensors for the in-beam measurement.Charge sharing function will be
investigated for more prototype sensors.Coupling capacitances will be determined
to understand the charge loss to neighboring strips.
To run data acquisition (DAQ) for laser scanning of sensors over EPICS.
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 14
Thank you for your Thank you for your attention!attention!
05-Mar-13 Laser Test Stand: P.Ghosh & J.Eschke 15
H35.6 ; A. Lymanets
Detector module development for the CBM-STS
H35.7 ; M. Singla
Study of low mass readout cables for the CBM-STS
H35.8 ; T. Balog
Performance of prototype module for the CBM-STS
H63.1 ; C. Pauly
The CBM experiment : Status and outlook
H68.7 ; A . Senger
FLUKA calculations for the CBM experiment
Tue
Thu
Other interesting talks