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, Lymanets 1,3, A. Melnyk1, V. Militsiya 1, O. Okhrimenko 1, A. Chaus1, D. Storozhik1, V. Zhora 41 KINR, Kiev 2 GSI, Darmstadt, 3 now at FIAS, J.W. Goethe University, Frankfurt,4 Institute of Microdevices (Kiev)

CBM Collaboration Meeting. GSI, Darmstadt. 10.03.2009

R&D: Agreement KINR-GSIA 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 sensorTwo-layer micro-cables were produced and bonded (IMD, Kiev) to match 50.7 m pitchCBM01 sensor (50 x 50 mm2) : Even strips to upper layer (101.4 m pitch); odd strips to the bottom layer (101.4 m pitch); - the same structure for p- and n-side of a sensor.

Micro-cablesA double-layer micro cables 25 m width20 m thick Al strips 101.4 m pitch on 24 m 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 step in X and Y directions (15x15 cm2) 10 .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 Charge, Strip kCharge, Strip k+1Total 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 m).The figures near dots indicate the coordinate of laser spot (in m)

Ra-226, 4 lines alpha-source. Charge, Strip kCharge, Strip k+1Measurements with radioactive sourcesInterstrip 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 -source . MIP hit triggerPM Si-strip coincidences.PM-1

PM-2Sr - 90 interfacePCPentium1200 MHzSi-det.Test Setup built and running at the KINR for (8 x n) channelsMeasurements with radioactive sources

Measurements with radioactive sources 90Sr -source (CBM01 sensors)p-strip MIP-spectraMIP-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 currentSupporting 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).