1. V.M. Pugatch Kiev Institute for Nuclear Research
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,
Lymanets 1,3, V. Militsiya 1, O. Okhrimenko 1, A. Chaus1,
D. Storozhik1, V. Zhora 4, V. Perevertailo 4,
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

2. 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

3. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

4. 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

5. 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

6. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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 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

7. Microcables for the discrete electronics readout
Side A:
Connecting
by ultrasonic bonding
to sensors
4 Different cables were needed
for every type of the sensors:
In total, 16 types cables were designed
and produced
Side B: Connecting by soldering to preamplifiers
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

8. Microcables for the discrete electronics readout
CBM01-B2-sensor
50,7 μm – pitch
Double-sided
Sensor is glued to the AEROPLAST
Carbon 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

9. 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

10. Cooling infrastructure
Thermo-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

11. Cooling infrastructure
Cooling studies
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

12. Cooling infrastructure
Thermo-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
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

13. 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

14. Sensors characterization
Mounting sensors on
Supporting AEROPLAST frame
Connecting p-, and n-strips
by microcables to LEMO
connectors – inputs to PA
onnectr
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

15. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Measurements with radioactive sources
Ra-226, 4 lines – alpha-source.
Test setup at KINR:
coincident energy spectra
for pairs of adjacent strips
Charge, Strip ” k”
Interstrip gap data
strips functionality
charge sharing
full depletion voltage
Charge, Strip “k+1”
Irradiation in two steps:
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

16. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Measurements with radioactive sources
CBM01-B1-sensor 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

17. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Measurements with radioactive sources
CBM01-B1-sensor μm - pitch
226 Ra from n-side,
HV = 10 V HV = 30 V
Approaching full depletion voltage …
Yet! There was never clear separation
of events belonging to 4 alpha-lines :
Thick ( μm) dead layer from n-side ?
Non-depleted sensor,
N-strips are shortened
(events along the diagonal)
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

18. Interstrip gap – charge collection efficiency low ?
Depletion Voltage
0 V V V
Single strip spectrum
Coincident spectra of adjacent strips
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

19. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Measurements with radioactive sources
Sr-90 – β-source (selecting its MIP part).
MIP – trigger (high energy tail in PM-2)
Measuring PM – Si-strip coincidences.
Sr - 90
РС –
interface PC
Pentium
1200 MHz
PM-1
Si-det.
PM-2
Test Setup at KINR
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

20. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Measurements with radioactive sources 90Sr – β-source (CBM01-B2 sensor)
p-strip MIP-spectra
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

21. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Measurements with radioactive sources 90Sr – β-source (CBM01-B2 sensor)
n-strip MIP-spectra – non Landau shape – noise from high leakage current smears spectrum
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

22. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
Laser test setup
LHCb Laser setup
at Zurich University –
Measuring in atmosphere
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

23. Laser test setup at KINR
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

24. 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

25. 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

26. Laser test setup at KINR
Laser spot moving
from one
strip to another one
also changing
a spot brightness
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

27. 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

28. Laser test setup at KINR
Analog signals
From adjacent strips-
Laser spot is close to one of
the strips (large amplitude)
Negative pulse at another
strip – reason unknown
Plan to check
whether this
happens also
for particles
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

29. Laser test setup at KINR
V. Pugatch CBM Collaboration Meeting, Dubna, Oct

30. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008
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).
V. Pugatch CBM Collaboration Meeting, Dubna, Oct