cbm silicon tracking system. cbm-01 sensors characterization
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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)
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.
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.
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
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
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.
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)
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
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
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.
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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