v. pugatch cbm collaboration meeting, dubna, oct. 13-17 2008 1 cbm silicon tracking system. results...
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CBM Silicon Tracking System.Results of the pre-prototype
detector module test.V.M. Pugatch
Kiev Institute for Nuclear Research
Thanks to coauthors: M. Borysova 1, J.M. Heuser 2, O. Kovalchuk 1, V. Kyva 1,
A. Lymanets 1,3, V. Militsiya 1, O. Okhrimenko 1, A. Chaus1, B. D. Storozhik1, V. Zhora 4, V. Perevertailo 4,
C. Galinskiy 5
1 KINR, Kiev 2 GSI, Darmstadt,
3 now at FIAS, J.W. Goethe University, Frankfurt,4 Institute of Microdevices (Kiev)
5 SPA AEROPLAST (Kiev)
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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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.
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Prototype for evaluations: LHCb Silicon Tracker – supporting boxes with cooling pipes
Cooling infrastructure and temperature monitoring for the CBM detector module - design at the AEROPLAST (Kiev).Cooling inside of the supporting ladders …
Negotiations are in progress wrt involvement into the Detector Module Cooling activity of joint German-Ukrainian venture Labor-Technik LTD www.labor-technik.com.ua
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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ASSEMBLY of the Module prototype
• 1st prototype – the design similar to the long ladders of the LHCb Silicon Tracker – modified for the double-sided version of sensors
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Prototype Module assembly scheme
Separated heat flow by making different supporting frames : - for hybrids with readout chips - for Si-sensor (to prevent heating of the sensor)
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Supporting frame A low mass module- to minimize multiple Coulomb-scattering of charged particles in the
detector and support materials. • AEROPLAST(Kiev) – design and production:
Three-layer frames composed by two flat plates (0.25 mm thick) with foam layer (1 mm thick, density - 0.7 g/cm3) in between three types to match the sizes of prototype silicon sensors CBM01, CBM01-B1, CBM01-B2 .
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Microcables for the discrete electronics readout
Side A:Connecting by ultrasonic bondingto sensors
Side B: Connecting by soldering to preamplifiers
4 Different cables were neededfor every type of the sensors:In total, 16 types cables were designed and produced
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Microcables for the discrete electronics readout
CBM01-B2-sensor
50,7 μm – pitch
Double-sided
Sensor is glued to the AEROPLASTCarbon fiber supporting frame
Microcables are bonded to sensor pads:Even strips – to one side; odd strips to the opposite side
LEMO connectors are soldered by wires to large pads on microcables
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Micro-cables suitable for connecting sensors and n-XYTER microchip
A double-layer micro cable
• 25 µm wide, 20 µm thick Al strips• 101.4 µm pitch • on 24 µm thick polyimide film
has been designed and produced at the Institute of Microdevices (IMD, Kiev).
Different cables of that type have been tested using them for the CBM01 (50 x 50 mm2 ) sensor readout by a discrete electronics
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Cooling infrastructureThermo-isolating box shielded against r/f
pick-up has been designed and built.
Thermo sensors (two types) • Pt-100 • Institute of Microdevices (Kiev) production (based on microcable technology)
were installed to monitor temperature at different areas of the detector module
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Cooling infrastructure
Cooling studies
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Cooling infrastructureThermo-mechanical tests with dummy silicon samples glued by silicon glue onto
the supporting frames:
• perfect mechanical rigidity for all supporting frames but one • thermo-conductivity appr. 0.6 W/m*deg in the longitudinal direction• A special design has been developed for investigating cooling by circulating a
liquid agent in hollow plates. Currently such structure didn’t show needed mechanical stability. It might be improved at the price of increasing the transversal size of the frame up to 5 mm (keeping material budget still within a required 0.3 X0 ).
• Negotiations with joint German-Ukrainian venture Labor-Technik LTD
www.labor-technik.com.ua
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Sensors characterization
• The first detector module prototypes equipped with 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.
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Sensors characterization
•Mounting sensors on Supporting AEROPLAST frame•Connecting p-, and n-stripsby microcables to LEMO connectors – inputs to PA
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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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 voltage
Test setup at KINR: coincident energy spectra for pairs of adjacent strips
Irradiation in two steps: 1. from p-side (4-lines structure should be clearly pronounced at any allowed depletion voltage)2. from n-side (4-lines structure should appear at full depletion
voltage)
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Measurements with radioactive sourcesCBM01-B1-sensor 80 μm – pitch,
226 Ra from p-side, p-strips read-out, HV 0 – 50 V
Unexpected performance !Illustrates problem with electric field in the interstrip gap
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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CBM01-B1-sensor 80 μm - pitch
226 Ra from n-side,
HV = 10 V HV = 30 V
Approaching full depletion voltage …Yet! There was never clear separationof events belonging to 4 alpha-lines :Thick (10 -15 μm) dead layer from n-side ?
Non-depleted sensor,N-strips are shortened(events along the diagonal)
Measurements with radioactive sources
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Interstrip gap – charge collection efficiency low ?
• Depletion Voltage
0 V 4 V 4 V
Coincident spectra of adjacent strips Single strip spectrum
Sr-90 – β-source (selecting its MIP part). MIP – trigger (high energy tail in PM-2)Measuring PM – Si-strip coincidences.
PM-1
PM-2
Sr - 90
РС –interface
PCPentium1200 MHz
Si-det.
Test Setup at KINR
Measurements with radioactive sources
Measure Landau MIP peak (for p- as well as n-strips)as a function of depletion voltage:Determine full depletion voltage
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Measurements with radioactive sources 90Sr – β-source (CBM01-B2 sensor)
• 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 have nice Landau-shape at low depletion voltage, while at higher than 30 V the noise makes it gaussian-like one.
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Measurements with radioactive sources
90Sr – β-source (CBM01-B2 sensor)
• n-strip MIP-spectra – non Landau shape – noise from high leakage current smears spectrum
0 10 20 30 40 50 60 70 800
50
100
150
200
250
300
350
400
Channel Number
Ev
en
ts
d00.141: Si-strip Component, 80 V
Threshold = 0Threshold = 20Threshold = 40
MIP peak - 21st channel
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup
LHCb Laser setup at Zurich University –Measuring in atmosphere
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup at KINR
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup CBM01 sensors test results
Interstrip gap is irradiated by focused laser beam. Coincident spectra at different depletion voltage from n –side allow determination of full depletion voltage.
Notice: linear response exists at very narrow central part of the interstrip gap – -close to 5 μm, only - Necessity to measure precisely η-function – for improving hit position resolution
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup at KINR
4th year students from Kiev University – Measuring η-function For the CBM-01 sensor
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup at KINRLaser spot moving from onestrip to another onealso changing a spot brightness
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup at KINR
Analog signals from adjacent strips –Laser spot appr.at the middle of the interstrip gap
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup at KINR
Analog signals From adjacent strips-Laser spot is close to one ofthe strips (large amplitude)
-Negative pulse at anotherstrip – reason unknown
Plan to check whether thishappens also for particles
V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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Laser test setup at KINR
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Summary. Outlook• Test setup (r/a sources, laser, cooling infrastructure) was designed and
built at KINR
• Pre-Prototype Detector Module components (supporting frames, sensors, microcables, cooling) and their connections were tested.
• Results:– B1, B2 - 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).