1. 1 J.M. Heuser − Silicon detector systems for CBM Silicon detector systems for CBM Johann M. Heuser, GSI CBM meeting, University of Jammu, 14 February 2008 Silicon Tracking System Micro Vertex Detector Silicon Tracking Layer in MUCH ? Overview of Tasks & environments Detector technologies System concepts Technical challenges & prototyping

2. 2 J.M. Heuser − Silicon detector systems for CBM CBM – Electron-Hadron setup RICH TRDsECALTOF target beam PSD STS + MVD

3. 3 J.M. Heuser − Silicon detector systems for CBM MVD + STS MUCH TRDTOF target beam PSD CBM – Muon setup

4. 4 J.M. Heuser − Silicon detector systems for CBM Tracking of up to ~700 charged particles per event Momentum determination with ~ 1% resolution Interaction rate up to 10 MHz Online r/o & reconstruction Unprecedented challenge in this combination. New innovative system concept & technologies ! UrQMD, Au+Au, 25 AGeV S T S S ilicon T racking S ystem Low-mass large-area, fast, radiation-hard detector system Task & Environment

5. 5 J.M. Heuser − Silicon detector systems for CBM STS S ilicon T racking S ystem 1 T dipole magnet 1 m 8 tracking stations microstrip detectors: thin, passive, high spatial resolution double-sided detectors (default) single-sided detectors in 16 stations: under study

6. 6 J.M. Heuser − Silicon detector systems for CBM amplifiers in r/o chip: pulse height pattern Silicon Microstrip Detectors Variety of constructions: single-sided double-sided DC-coupled r/o AC-coupled r/o strip lengths up to ~10 cm... n- n+ p+ + bias ("diode in reverse direction of operation") MIP in Si: ~ 80 e-h pairs per µm track charged particle typically 300 µm typically 50-100 µm h e-e- signal ~ 24k e - + + - - Al

7. 7 J.M. Heuser − Silicon detector systems for CBM Detector Concept Layout of the tracking stations  "sectorization" sector = certain number of sensors read out together Building block ("module") Performance evaluation Iterations of the layout Implementation of realistic sensors, support, material, backed up by detector R&D station 1, z=20 cm station 8, z=100 cm module sector, made from 3 detectors ~ 1 m 2

8. 8 J.M. Heuser − Silicon detector systems for CBM Detector Occupancy microstrip detectors, 60 µm strip pitch, 7.5 o angle front-back fraction of fired strips per detector

9. 9 J.M. Heuser − Silicon detector systems for CBM 2 projective coordinates in one thin silicon layer (  double-sided strip detectors) readout electronics outside tracking aperture ladder construction: electrical contacts at sensor's top/bottom edge no "dead" region in the detector corners, (despite of stereo angle front/back strips) radiation tolerance: design, material Technical challenge: Microstrip detectors CBM STS tracking station Detector module readout direction p side (front): "stereo" strips blue: double metal connect- ions of strips I to III "vertical" strips n side (back): "vertical" strips I II III CBM01: R&D study GSI-CIS with focus on Double-sided micro-strip detector, connectible at top and bottom row.

10. 10 J.M. Heuser − Silicon detector systems for CBM Microstrip detector prototype, GSI-CIS, 8/2007 4" wafer CBM01, 285 µm Si Test sensors Double-sided, double-metal, 1024 strips per side, 50.7 µm pitch, 15º stereo angle, full-area sensitive, contacts at top + bottom edge, size: 56  56 mm 2 Double-sided, single-metal, 256  256 strips, orthogonal, 50(80) µm pitch, size: 14  14 (22  22) mm 2 Main sensor Punch-through biasing. Polished float-zone Si. I-V tests: Work as expected. Addresses connectivity Next iteration: radiation tolerance Test board

11. 11 J.M. Heuser − Silicon detector systems for CBM Typical operation: about 6 years. Situation: Interaction rate: 10 7 /s Effective CBM run year: 2 months at full operation 5 × 10 6 s Approaches: - Fluences estimated with URQMD generated events - Fluence study with a FLUKA simulation of the CBM detector in its cave is ongoing Estimated tolerance: ~ 10 15 1-MeV n eq Challenge: Radiation Environment CBM cave beam STS dump detectoredge hit/cm 2 part/cm 2 /6yr dose/6yr STS @ 30cminner 10 7.5·10 14 20 Mrad outer 0.25 1.8·10 13 0.5 Mrad STS @ 1minner 1 7.5·10 13 2 Mrad outer 0.03 2.3·10 12 60 krad 1 CBM-year assumed as: 2 month at 100% duty cycle 4 month at 50% duty cycle

12. 12 J.M. Heuser − Silicon detector systems for CBM Challenge: Combinatorial hits microstrip detectors hybrid pixel detectors 1 central Au+Au event at 25 GeV/nucleon, tracking station at z=30 cm compared with track points : rec. points > 1:15 track points : rec. points 1:1 comb.hits thinthick true hits Y [cm] X [cm]

13. 13 J.M. Heuser − Silicon detector systems for CBM Challenge: Tracking in STS Central collisions Au+Au @ 25 AGeV ~ 1000 charged particles/event ~ 700 in aperture 2.5 – 25 deg up to ~ 30 tracks/cm 2 at z = 30 cm required momentum resolution ~ 1% efficiency [%] momentum [GeV/c] Performance study of an 8-station STS: Momentum resolution: Track reconstruction efficiency: includes cables, support (p > 1 GeV/c) tracks  [%] primary, p > 1GeV/c 98.5 all, p>1 GeV/c 96.1 all, p> 0.1 GeV/c 90.4 3.2 % "ghost tracks" Reconstructed central UrQMD event XY 78 ms on Pentium 4 processor XZ "Cellular Automaton + Kalman Filter" combinatorial hits 90 %

14. 14 J.M. Heuser − Silicon detector systems for CBM silicon sensors silicon sensors + mech. frame Momentum resolution STS with 8 microstrip tracking stations 400 µm Si per station 400 µm Si + 2 mm C ladder 400 µm Si + 2 mm C ladder + 2 mm Kapton silicon sensors + mech. frame + r/o cables [%]

15. 15 J.M. Heuser − Silicon detector systems for CBM material budget Al-Kapton cables: very thin (<50 µm total) long high-density strip lines 50 µm pitch low capacity (goal: S/N >10) high-density interconnections microstrip system ~20- 60cm % X 0 0.3 ~1........ >>1 r/o electronics Technical challenge: low-mass detector module 1024 lines of 50 µm pitch: Cable length limited. to <10 cm. 1024 lines of 100 µm pitch: Two-layer cable → 50 µm eff. pitch. Length up to ~50 cm seem possible.

16. 16 J.M. Heuser − Silicon detector systems for CBM Pre-prototype of ultra-low-mass readout cable Cooperation with SESRTIIE Kharkov, Ukraine. Structure: 55 cm length, 1024 lines, 100 µm line pitch Material: 14 µm Aluminum on 10 µm Kapton very challenging component

17. 17 J.M. Heuser − Silicon detector systems for CBM Challenge: Fast front-end electronics High interaction rates: Require a data driven front-end. n-XYTER chip 128 channels 50.7 µm pitch dual polarity 30 ns peaking time ~1.4 ns jitter thresholds: > 2700 e count rates: ~160 kHz/strip token ring r/o scheme power: ~ 13 mW/ch 0.35  m CMOS Used for CBM detector R&D: n-XYTER r/o hybrid for STS strip sensors. Compatible with CBM DAQ board prototypes. Lab and beam tests of STS. Future: Development of a new chip: CBM-XYTER. n-XYTER chip of the DETNI Consortium: Matches well CBM specs. Produced together with GSI.

18. 18 J.M. Heuser − Silicon detector systems for CBM Technical challenge: Front-End Board & interconnections Future CBM-XYTER chip detector/ readout cable 1024 channels per detector: 8  128-ch readout chips to ROC FEB r/o cable sensor ~60 µm line pitch Wire-bonding, tap- bonding of the thin fine-pitch structures? ~7 cm FEB floor plan: how to arrange 8 chips in close distance? 50.7 µm

19. 19 J.M. Heuser − Silicon detector systems for CBM Challenge: System integration Detector module: Electrical interconnections sensor-cable-FEE Mechanical assembly of - thin sensors + cables + front-end board - on mechanical support frame. Assembly steps single vs. double-sided module Grounding/shielding HV supply to sensors: through r/o cable, or extra cable? Tracking system: Mechanics Cooling of the fiducial volume? Insulation from hot FEE boards? sensor cable FEE

20. 20 J.M. Heuser − Silicon detector systems for CBM MVD M icro V ertex D etector 1 T dipole magnet 1 m 2 vertexing stations ultra-thin pixel detectors, very high spatial resolution very low-mass mechanical support + thermal management operated at sub-zero C temperatures in vacuum Pioneering a fully novel, world-record thin detector system technique based on CMOS monolithic pixel sensors on diamond supports

21. 21 J.M. Heuser − Silicon detector systems for CBM Add-on to tracking: Precision decay vertex identification (D,  c ), spatial resolution few tens µm Operational with at least 100 kHz interaction rate Online charm trigger New innovative system concept & technologies ! UrQMD, Au+Au, 25 AGeV MVD - Task & Environment Ultra-low-mass, radiation-hard detector system 782 rec. tracks 2% ghost tracks XZ 8 microstrip stations MVD

22. 22 J.M. Heuser − Silicon detector systems for CBM M A P D M onolithic A ctive P ixel D etectors Low-resistivity p-type Si hosting n-type charge collectors ("wells"): signal created in epitaxial layer Q ~ 80 e-h / μm  signal < 1000 e− charge sensed by n-well/p-epi junction excess carriers diffuse towards diode amplifier, CDS etc. on chip thickness as thin as 50 µm Cooperation with IPHC Strasbourg pixel: 10 – 40 µm pitch top view

23. 23 J.M. Heuser − Silicon detector systems for CBM 100 kHz full-frame readout Concept at IKF, University of Frankfurt MVD R&D effort Radiation hard sensors > 10 13 n equiv. MVD demonstrator module MAPS with column parallel readout Material budget of full system: < 0.3% X 0 or 300 µm Si ~ 5 cm Potential MVD demonstrator station at T= -20 C ultimately: Thin MAPS on thin industrial diamond support with integrated Al bus: 0.1-0.2 X 0 (150 µm Si) R&D with IPHC & Fraunhofer

24. 24 J.M. Heuser − Silicon detector systems for CBM D  (c  = 312  m): D +  K -  +  + (9.5%) D 0 (c  = 123  m): D 0  K -  + (3.8%) D 0  K -  +  +  - (7.7%) D  s (c  = 150  m): D + s  K + K -  + (5.3%)  + c (c  = 60  m):  + c  pK -  + (5.0%)  c reconstruction: Greatest challenge!! D 0 z-vertex resolution D + reconstruction Open Charm Reconstruction with such a detector system...

25. 25 J.M. Heuser − Silicon detector systems for CBM MVD + STS MUCH TRDTOF target beam PSD CBM – Muon setup

26. 26 J.M. Heuser − Silicon detector systems for CBM Track points in the first MUCH gap: similar to STS-8 10 MHz interaction rate High radiation dose Rather high granularity needed No material budget limit No material budget limit Silicon pad detectors + fast self- triggered FEE. Under discussion. UrQMD, Au+Au, 25 AGeV MUCH-Si1 - Task & Environment Large-area (1.3  STS-8), fast, radiation-hard detector system ~ 1 hit/cm 2 /event (Geant study, A. Kiseleva) MUCH-Si1

27. 27 J.M. Heuser − Silicon detector systems for CBM Wafer thickness 525 µm diode area 15 mm by 15 mm Depletion voltage 100-120 V Diode capacitance 37 - 41 pF Bias for full depletion 20 V Leakage current < 300nA total, <20nA/pad Junction breakdown > 300V Polysilicon bias resistor 1 M  from: Proposal for a Nosecone Calorimeter (NCC) for the PHENIX Experiment BNL, 3/2006 CBM01 wafer Microstrip pad detectors Area diodes; typical size ~ mm 2 up to many cm 2 Example: PHENIX pad detector prototypes (MSU/ELMA) PHENIX pad detector prototypes pad diode test structures, few mm 2 area

28. 28 J.M. Heuser − Silicon detector systems for CBM sectorization study of 1st tracking station (zones of ~ same occupancy) r = 0.8 m sectors with 8 x 16 = 128 pads possible "module" (M. Ryzhinskiy) Possible MUCH Si tracking station # size pad size pad area sectors [cm x cm] [mm x mm] [mm 2 ] 160 2.22 x 2.22 2.8 x 1.4 4 84 2.22 x 4.44.. 64 4.44 x 4.44.. 48 4.44 x 8.88.. 28 8.88 x 8.88.. 48 8.88 x 19.76 11 x 12.5 140 challenges: connection of r/o electronics to many SMALL pads check radiation env. CBM-XYTER — From sectors to pads — 128 chs.

29. 29 J.M. Heuser − Silicon detector systems for CBM Summary CBM will comprise two, maybe three silicon detector systems unprecendeted performance will be required thin, fast, efficient/redundant, radiation hard: new/fully exploited state-of-the art technologies challenge is especially in the system design most important: planning/evaluation in reliable simulation studies characterization of prototypes from early on STS: start to approach this phase simulation & prototyping MVD: detector R&D active, system design/simulation mostly t.b.d. MUCH-Si1: upcoming new activity, t.b. planned