ADC values Number of hits Silicon detectors1196  6.2 × 6.2 cm  4.2 × 6.2 cm  2.2 × 6.2 cm 2 52 sectors/modules896 ladders~100 r/o channels1.835 M r/o chips14.4 k r/o boards~2080 hub boards~180 Silicon Tracking System The Silicon Tracking System (STS) is the central detector of the Compressed Baryonic Matter (CBM) experiment at FAIR. Its task is the standalone trajectory reconstruction of the high multiplicities of charged particles originating from high-rate beam-target interactions. The silicon microstrip detectors must be radiation hard and are red out by a fast self-triggering front-end electronics. Characterization Tests Tests for each sensor Tests for each strip Tests for structures Process stability tests Irradiation tests Bonding & Module assembly Characterization Characterization & Quality assurance for silicon sensor includes 1.Visual tests on arrival 2.Control & distribution to testing centers 3.Verification of specifications via tests 1.Electrical tests 1.Bulk IV & CV tests 2.Strip response (Coupling & Bias) 3.Inter-strip parameters 2.Radiation hardness tests 3.Long-term stability tests 4.Bonding tests 5.Module tests 4.Central database for keeping track of sensor response Silicon microstrip sensors CBM01 1 st full-size prototype close-up of a corner of double-sided microstrip detector CBM01 (thickness 300 µm & strip pitch 58 µm) schematic view of silicon sensor with contacts pads & bias rail * Testing station Semi-automatized using LabVIEW programs & Wafer prober Bulk capacitance Radiation damage on leakage current Bias resistance Interstrip resistance Coup. capacitance Probe station Zuess 3000 Leakage current STS is engaged in detector development since Prototype detectors in collaboration with CiS Erfurt and Hamamatsu Photonics. STS will be populated with ~1200 double sided microstrip sensors. 2-5 kΩ resistance 58 µm pitch ±7.5 °Strip stereo angle 4 AC pads/strip 1 DC pad/strip 18 µm strip width 300 µm thick Silicon Double metallization for stereo angular strip connection Bulk Measurements Resistance & Capacitance Interstrip Measurements Int.strip capacitance Radiation damage on strip current and depletion voltage Focuser CBM02 sensor Optical fiber Laser & optical fiber setup Laser Step Motor Focuser Optical Fiber Sensor Read-Out Station Box Interlock Optimization of focuser position With Laser tests we investigate Scanning sensor Strip integrity Detector response with mimicking 1MIP Charge sharing b/w strips Fig. 3. Lego plot of hit position : CBM02 Fig.4 Charge sharing CBM02: (Preliminary) Minimum Ionizing Particle (MIP) create ~ 22 ke - in our 300 µm thick silicon sensors, which corresponds to ≈ 180 ADC counts. The purpose of illuminating the double sided microstrip silicon sensor is to induce the same amount of charge as in case of a MIP. Based on the absorption of light in silicon, we selected infrared light (λ=1060 nm) which has absorption depth of ~500 µm in silicon. For the systematic evaluation of the performance of our sensors we used pulsed (~10 ns) infrared laser with a focused spot size ~15 µm. We have illuminated prototype sensor (256 strips/side) with the pulsed laser (~10 ns) and could focus the width of the laser spot to one strip per side. The preliminary results are shown above. We are successful in inducing right amount of charge (22 ke - ). Fig. 1,2 & 3 shows Channel fired/side, Cluster amplitude similar order of ADC counts as for MIPs & 3D distribution of hit respectively. Preliminary result from Charge sharing between the strips is presented in Fig. 4. Fig. 1. Counts/strip on nside: CBM02 Strip number Number of hits Systematic Characterization & Quality Assurance of Silicon Microstrip Sensors for the Silicon Tracking System at the CBM Experiment Pradeep Ghosh Pradeep Ghosh*-- for the CBM Collaboration Goethe University, Frankfurt am Main, Germany and GSI Helmholtz center for Heavy Ion Research, Darmstadt, Germany Fig. 2. Cluster amplitude on nside: CBM02 Bulk Measurements: 1.Leakage Current 2.Bulk Capacitance Sensor Measurements: 1.Bias resistor 2.Coup. Capacitance Interstrip Measurements: 1.Interstrip Resistance 2.Interstrip Capacitance Strip current & Long term stability Radiation Damage Open Strip Shorted Strip “Pinhole” (short between implant and metal) Open bias resistor Open implant at via Open implant: Pinhole Tests Pinhole testing schematic Pinhole test Scheme at Wafer prober Common strip failures & pinhole* Laser Tests *From CMS Exp. Strip current Current Stability 1.5x1.5 cm 2 = 256 strips 5.5x5.5 cm 2 & 6.2x6.2 cm 2 has 1024 strips Current stability Tests done for more than 2 days