Semiconductor Detectors Stefan Heindl and Martin Printz KSETA Doctoral Researchers Workshop, Lauterbad, 17.10.2013 Institut für Experimentelle Kernphysik KIT – University of the State of Baden-Wuerttemberg and www.kit.edu National Research Center of the Helmholtz Association
Large Hadron Collider (LHC) Proton Proton collisions @ 8 TeV Four experiments: ATLAS, CMS, ALICE and LHCb Jura Genf 9 km 100 m KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 2 Institut für Experimentelle Kernphysik 17.10.2013
Compact Muon Solenoid (CMS) Myon detectors Superconducting coil Calorimeters: Tracker: in magnet yoke (3,8 T): Deflection of Determination of energies Determination of charged particles trajectories +z Interaction point 21 m long, 16 m high, 12500 t Beam axis KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 3 Institut für Experimentelle Kernphysik 17.10.2013
Silicon Tracker – The Heart of CMS 2.4m Si sensors FE electronics 10x20cm 2 TEC Module 200m 2 of silicon-only Tracker with pixel and strip sensors provide up to 13 track points for Momentum determination Charge assignment Vertex reconstruction Carbon fibre support Power + Data KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 4 Institut für Experimentelle Kernphysik 17.10.2013
Why? Higgs candidate ZZ event (@ 8 TeV) with 2 µ and 2 e KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 5 Institut für Experimentelle Kernphysik 17.10.2013
Why? CMS collaboration has 3500 members Physicists, PhD students, engineers, technicians and administrative staff Working together for one goal: “So that I may perceive whatever holds The world together in its inmost folds” (Goethe, Faust 1) Nobel Prize 2013 for F. Englert and P. Higgs: Higgs boson discovered by ATLAS and CMS collaborations at CERN KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 6 Institut für Experimentelle Kernphysik 17.10.2013
LHC planning Future of LHC: Phase 1 Phase 2 LS 1 LS 2 8*10 33 1*10 34 2*10 34 >8*10 34 LS 3 Two planned upgrades for all LHC experiments At CMS : Phase 1: Exchange of pixeldetector , new readout for calorimeters, … Phase 2: Exchange of complete silicon tracker , new L1 trigger system, extension of myon system, … KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 7 Institut für Experimentelle Kernphysik 17.10.2013
Silicon Sensor Working Principle Mini strip test sensor SiO 2 (2.5x3.5cm 2 ) Depletion zone (at pn-junction) created by application of reverse bias voltage Traversing charged particles create electron-hole pairs e-h pairs are separated by electric field Drifting charge induces signal on AC coupled strips Readout electronics wire bonded to strips KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 8 Institut für Experimentelle Kernphysik 17.10.2013
Silicon Strip Sensor Layout: F. Hartmann, Evolution of Silicon Sensor Technology in Particle Detectors, Springer 2008 KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 9 Institut für Experimentelle Kernphysik 17.10.2013
PHASE II: UPGRADE OF THE CMS TRACKER KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 10 Institut für Experimentelle Kernphysik 17.10.2013
Phase II Upgrade – Why Upgrade? LHC Tracker lifetime designed for runtime of the LHC Upgrade of the LHC: HL -LHC (2022) H igher L uminosity (particles / area / time) ~100 primary vertices / 40MHz Requirements Radiation hard sensors (increase of fluence) Thinner sensors (less radiation length) HL-LHC High granularity and trigger contribution [1] Pixel: Casse et al. 2008 [2] Strips: Rohe et al. 2005 [DOI 10.1016/j.nima.2009.01.196] New Tracker necessary for upgraded LHC! KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 11 Institut für Experimentelle Kernphysik 17.10.2013
CMS High Pileup Run 2012: 78 reconstructed vertices KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 12 Institut für Experimentelle Kernphysik 17.10.2013
Sensor R&D Activities Campaign within CMS Tracker Collaboration (total 17 institutes) Radiation hardness study of different silicon base materials: Floatzone (FZ), Magnetic Czochralski (MCz) and Epitaxial (Epi) Different bulk doping: p- and n-type Strip sensors Different thicknesses: e.g. 200 and 320 µm 164 wafers with identical layout Pixel from one vendor (Hamamatsu) sensors Geometry variations Diodes Test structures KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 13 Institut für Experimentelle Kernphysik 17.10.2013
Sensor R&D Activities Layout example: 6“ „ITE wafer“, completely designed inhouse Foundry: ITE Warsaw KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 14 Institut für Experimentelle Kernphysik 17.10.2013
Sensor R&D Activities Layout example: 6“ „ITE wafer“, completely designed inhouse Foundry: ITE Warsaw KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 15 Institut für Experimentelle Kernphysik 17.10.2013
Sensor R&D Activities Reason for sensor degradation: Defects Radiation damage introduces defects in the silicon crystal Increase of leakage current (a) Generation of space charge: increase of depletion voltage (b) Trapping of charge carriers: reduction of signal and collected charge (c) Vacancy and interstitial atom (a) (b) (c) Energy-band model of silicon KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 16 Institut für Experimentelle Kernphysik 17.10.2013
Irradiation Intentional irradiation of sensors Five different fluences chosen corresponding to five Tracker radii @3000fb -1 Protons and neutrons Proton irradiation at Zyklotron AG, Karlsruhe Neutron irradiation at TRIGA reactor, Ljubljana [M. Guthoff, 2012] KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 17 Institut für Experimentelle Kernphysik 17.10.2013
Probestation Self-built semi-automatic probestation: Lightproof housing Microscope with camera Electrometers PC Power supplies HV supply Relays Screen ISO-box Cooled movable jig LCR meter Commercial setup: >100k€ (without devices) KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 18 Institut für Experimentelle Kernphysik 17.10.2013
Probestation Relay schematics: HV supply Electrometer ISO- LCR box meter Jig KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 19 Institut für Experimentelle Kernphysik 17.10.2013
Probestation LabVIEW control software: KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 20 Institut für Experimentelle Kernphysik 17.10.2013
Sensor Qualification with Probestation After irradiation Current-Voltage Before irradiation Capacitance Measurement of electrical characteristics -Voltage Leakage current Depletion Voltage Depletion voltage Strip properties KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 21 Institut für Experimentelle Kernphysik 17.10.2013
Sensor Qualification with Probestation After irradiation Current-Voltage Before irradiation Capacitance Measurement of electrical characteristics -Voltage Leakage current Depletion Voltage Depletion voltage Strip properties KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 22 Institut für Experimentelle Kernphysik 17.10.2013
Radiation Hardness – Current T=20°C Expectation Currents in both n- and p-type material scale the same Additional thermal power needs to be cooled CO 2 cooling at -20°C foreseen for Phase II upgrade At lower T lower Δ I Prevent / control annealing Δ𝐽 Increase of leakage current 𝑊 ∝ F 𝑓𝑓 proportional to fluence: KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 23 Institut für Experimentelle Kernphysik 17.10.2013
Radiation Hardness – Depletion Voltage Voltage needed to create depletion zone increases Thicker sensors require higher voltages V dep in p-bulk sensors increases faster due to acceptor-like defects P-bulk FZ320N FZ320P T = -20°C FZ200N >1000V FZ200P f = 1kHz MCZ200N Depletion Voltage (V) 1000 MCZ200P N-bulk 800 600 400 200 0 0.0 14 15 15 5.0x10 1.0x10 1.5x10 Fluence (n eq /cm²) KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 24 Institut für Experimentelle Kernphysik 17.10.2013
Strip Readout System (Signal) – ALiBaVa Measure performance of sensors with real signals XYZ stages Collimator for 90 Sr source Sensor Daughterboard Peltier cooling Water cooling for Peltiers Scintillator for triggering Isolation and shielding KSETA Doctoral Researchers Workshop S. Heindl, M. Printz – Semiconductor Detectors 25 Institut für Experimentelle Kernphysik 17.10.2013
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