1. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 1 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. Chaus 1, B.D. Storozhik 1, 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)

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

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

4. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 4 ASSEMBLY of the Module prototype 1 st prototype – the design similar to the long ladders of the LHCb Silicon Tracker – modified for the double-sided version of sensors

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

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

7. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 7 Microcables for the discrete electronics readout Side A: Connecting by ultrasonic bonding to sensors Side B: Connecting by soldering to preamplifiers 4 Different cables were needed for every type of the sensors: In total, 16 types cables were designed and produced

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

9. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 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 mm 2 ) sensor readout by a discrete electronics

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

11. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 11 Cooling infrastructure Cooling studies

12. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 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 www.labor-technik.com.ua

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

14. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 14 Sensors characterization Mounting sensors on Supporting AEROPLAST frame Connecting p-, and n-strips by microcables to LEMO connectors – inputs to PA

15. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 15 Ra-226, 4 lines – alpha-source. Charge, Strip ” k” Charge, Strip “k+1” Measurements with radioactive sources Interstrip gap data strips functionality charge 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)

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

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

18. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 18 Interstrip gap – charge collection efficiency low ? Depletion Voltage 0 V 4 V 4 V Coincident spectra of adjacent strips Single strip spectrum

19. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 19 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 PC Pentium 1200 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

20. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 20 Measurements with radioactive sources 90 Sr – 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.

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

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

23. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 23 Laser test setup at KINR

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

25. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 25 Laser test setup at KINR 4 th year students from Kiev University – Measuring η-function For the CBM-01 sensor

26. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 26 Laser test setup at KINR Laser spot moving from one strip to another one also changing a spot brightness

27. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 27 Laser test setup at KINR Analog signals from adjacent strips – Laser spot appr. at the middle of the interstrip gap

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

29. V. Pugatch CBM Collaboration Meeting, Dubna, Oct. 13-17 2008 29 Laser test setup at KINR

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