Transcript
Page 1: CBM Silicon Tracking System. CBM-01 sensors  characterization

CBM Collaboration Meeting. GSI, Darmstadt. 10.03.2009

CBM Silicon Tracking System.CBM-01 sensors characterization.

V.M. Pugatch

Kiev Institute for Nuclear ResearchThanks to coauthors:

M. Borysova 1, J.M. Heuser 2, O. Kovalchuk 1, V. Kyva 1, A. Lymanets 1,3, A. Melnyk1, V. Militsiya 1, O. Okhrimenko 1, A. Chaus1,

D. Storozhik1, V. Zhora 4

1 KINR, Kiev 2 GSI, Darmstadt,

3 now at FIAS, J.W. Goethe University, Frankfurt,4 Institute of Microdevices (Kiev)

Page 2: CBM Silicon Tracking System. CBM-01 sensors  characterization

R&D: Agreement ‘KINR-GSI’

• A low-mass mechanical assembly of double-sided silicon microstrip sensors and their connection through analog readout cables to a readout electronics

• construction of an experimental test stand

• A quality assurance procedure suitable for a future larger detector module production.

Page 3: CBM Silicon Tracking System. CBM-01 sensors  characterization

Mounting CBM01 sensorHollows were made in a supporting frame (AEROPLAST Carbon fiber) supporting frame to allow bonding from both sides of the double-sided CBM01 sensor

Two-layer micro-cables were produced and bonded (IMD, Kiev) to match 50.7 μm pitchCBM01 sensor (50 x 50 mm2) : Even strips – to upper layer (101.4 μm pitch); odd strips to the bottom layer (101.4 μm pitch); - the same structure for p- and n-side of a sensor.

Page 4: CBM Silicon Tracking System. CBM-01 sensors  characterization

Micro-cablesA double-layer micro cables • 25 µm width• 20 µm thick Al strips • 101.4 µm pitch • on 24 µm thick polyimide film have been designed and produced at the Institute of Microdevices (IMD, Kiev).

Different cables of that type have been testedby implementing them for the CBM01 sensors

readout

Page 5: CBM Silicon Tracking System. CBM-01 sensors  characterization

Sensors characterization

• CBM01B1, CBM01B2 as well as CBM01 sensors have been mounted and connected to a discrete electronics at the readout board.

• Tests are performed at KINR using laser pulses (640 nm) and radioactive sources.

IV - CBM01Laser pulse amplitude at n-side strips as a function of the applied voltage (irradiation from the n-side).

Full Depletion Voltage- CBM01

Page 6: CBM Silicon Tracking System. CBM-01 sensors  characterization

Laser Stand - a part of the Quality Assurance System

Laser Stand (LS) for testing STS Si-microstrip detector moduleshas been designed and built at KINR. laser beam wavelength – 640 nm, diameter of the laser beam spot ~10 µм step in X and Y – directions (15x15 cm2) –10 µм.

Response of two adjacent strips:Laser beam was moved from one strip to another.

Software/hardware allows to move a laser beam over the silicon detector surface.

Page 7: CBM Silicon Tracking System. CBM-01 sensors  characterization

Laser beam characterization of CBM01 sensors

Cha

rge,

Str

ip ”

k”

Charge, Strip “k+1”Total pulse amplitude from two adjacent strips versus detector voltage (laser beam, 640 nm, from the p-side).

Two-dimensional spectra show unexpected performance of the inter-strip gap: total amplitude goes down at 40 V in comparison with unbiased sensor, linear inter-strip region gets narrower at 40 V (from 25 to few μm).

The figures near dots indicate the coordinate of laser spot (in μm)

Page 8: CBM Silicon Tracking System. CBM-01 sensors  characterization

Ra-226, 4 lines – alpha-source.

Cha

rge,

Str

ip ”

k”

Charge, Strip “k+1”

Measurements with radioactive sources

Interstrip gap datastrips functionalitycharge sharing full depletion voltageleakage current

Test setup at KINR: coincident energy spectra for pairs adjacent strips

Spectrum is deteriorated when a biasing voltage is applied. Amplitude of signals decreases:Unexpected performance in the inter-strip gap

Page 9: CBM Silicon Tracking System. CBM-01 sensors  characterization

Sr-90 – β-source . MIP – hit triggerPM – Si-strip coincidences.

PM-1

PM-2

Sr - 90

РС –interface

PCPentium1200 MHz

Si-det.

Test Setup built and running at the KINR for (8 x n) channels

Measurements with radioactive sources

Page 10: CBM Silicon Tracking System. CBM-01 sensors  characterization

Measurements with radioactive sources 90Sr – β-source (CBM01 sensors)

• p-strip MIP-spectra

0 10 20 30 40 50 60 70 800

200

400

600

800

1000

1200

1400

1600

Channel Number

Ev

en

ts

d00.126: Si-strip Component, 10 V

Threshold = 0Threshold = 10Threshold = 30

MIP peak - 10th channel

0 10 20 30 40 50 60 70 800

50

100

150

200

250

300

350

400

450

Channel Number

Ev

en

ts

d00.124: Si-strip Component, 30 V

Threshold = 0Threshold = 10Threshold = 40

MIP peak - 16th channel

10 20 30 40 50 60 70 80

10

15

20

25

MIP

Po

sit

ion

, C

ha

nn

el

Voltage, V

MIP-spectra for all types of sensors haveLandau-shape at low bias voltage.At bias voltage higher than 30 V it is of a gaussian shape.

Page 11: CBM Silicon Tracking System. CBM-01 sensors  characterization

Summary. • Pre-Prototype Detector Module components (supporting frames, sensors, microcables, cooling) and

their connections were produced and tested.• All type of CBM01 sensors:

-Unexpected performance in the interstrip gap. -Long term instability of the leakage current

• Supporting frames perfect features (low mass, mechanical rigidity, thermoconductivity, easy

connection and geometry shaping etc.,)

• Microcables (including double-layer structure) perfect electrical and mechanical features matching CBM request.

• Real Modules assembly and their Quality Assurance could be provided by KINR in collaboration with IMD (Kiev),

IAP (Sumy) and AEROPLAST (Kiev).


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