The D0 Silicon Microstrip Tracker (D0SMT)

1. The D0 Silicon Microstrip Tracker (D0SMT) Outline • Design • Detector Studies Coupling capacitors Radiation Damage LASER tests • Electronics and readout • Mechanical Assembly • Production Testing • Summary and prospects • Installation in the spring of 2000

2. D0SMT Components • Major SMT Subsystems • Single Sided Ladder (3 chip) • Double Sided 2o Ladder (9 chip) • Double Sided 90o Ladder (6 chip) • H Disk (SS back-to-back) • F Disk (DS)

3. Barrel/Disk Module

4. H DISK • Silicon IR = 94.5 mm, OR = 236 mm at wedge centerline • Readout mounts on outer silicon detector • Wedges alternate between two surfaces of a central cooling/support channel • Effective stereo angle = 15o

5. F Disk • Silicon IR = 26 mm, OR = 105.27 mm at wedge centerline • Readout mounts outboard of silicon, which allows disk to fit within a gap of 8 mm • Wedges alternate between two surfaces of a centralcooling/support channel (beryllium) • Effective stereo angle = 30 degrees • p-side Trace angle = -15o with respect to wedge centerlinePitch = 50 μm • n-side Trace angle = +15o with respect to wedge centerlinePitch = 62.5 μm

6. Capacitor Studies • In a double sided detector with grounded electronics, coupling capacitor breakdown will limit the lifetime of the detector. • Studies • Eliminate “black hole” effect in the SVX chip by bypassing parasitic transistor at the input (see VTX ‘96) • Effect of wirebonding on capacitor breakdown • 5-10% of capacitors fail at 50-100V after bonding (normally Vbd=140V) on SS detectors • No excess failures see on DS detectors with PECVD layer

7. n-side Capacitor Studies • When electronics are connected to the n-side of a detector with shorted capacitors we see an anomalous current from the amplifier input • Current is reduced when electronics is disconnected • Effect seen on n-side only • Caused by forward bias of the p-stop n junction

8. n-side Capacitor Studies

9. Irradiation Studies • Expect ~1 Mrad exposure for the inner layer per 4fb1 • Irradiation with • 8 GeV Protons from the Fermilab booster • 1 MeV Neutrons (Lowell Mass.) • Study • Evolution of deletion characteristics • Performance of detector and electronics

10. Irradiation StudiesCluster size

11. Irradiation Studiesnoise

12. H Disk Irradiation Depletion voltage (volts) Neutron fluence (1013/cm2) Neff (1011/cm3) Neutron fluence (1013/cm2)

13. Neutron Studies Detector Studies using ~1 MeV neutron source

14. Irradiation StudiesLASER Plateau

15. Detector Production • Five detector types - 3-chip, 9-chip, 6-chip, F wedge, H wedge. • All radiation testing complete • laser and cosmic ray studies • Measure in-situ rise times • charge sharing distributions • Probe testing • 100 V capacitor breakdown test on each channel • CV or alpha test to measure depletion • IV Test • Spot checks on • Interstrip resistance • Coupling capacitance • Strip currents

16. Micron Detector Delivery Needed for schedule Needed for schedule

17. Readout System

18. D0SMT - Electronics • SVXII Chip - done and tested • Most issues involve bypassing and clock quality • Needs careful hybrid(HDI) design • HDIs - delivery pacing production • Single layer flex 4 mil pitch, 2 mil vias • Cables: • low mass, good frequency response (53 Mhz), low attenuation, no reflections, no radiation of clock signal to the calorimeter, fits in the allowed space. • High impedance stripline • 3 segments • low mass section of varying length • low mass fixed length • “high mass” high quality section • System tests underway now

19. Where we were “burned” • HDI flex circuit - good prototypes but no good production circuits • Find reliable company (Dyconex) • pay extra $$$ • Detector delivery - ordered detectors 2 years early but waited for BABAR, H1… • still a serious problem • Cables • low mass, high impedance striplines are difficult • pay extra $$$ • But we are now in production and expect to be on schedule

20. Mechanical Systems • Design Philosophy • Build planar assemblies (ladders, wedges, disks) precisely under (Zeiss) CMM • Use mechanical tolerances to determine ladder placement in barrel (~15 mm) • Minimum Mass • Be support structures • Carbon fiber overall support

21. Ladder Assembly

22. Module Assembly

24. Ladder Assembly • Match notches in Be support to posts in bulkhead • 15 micron tolerance on Notched and posts • 2 micron tolerances achieved in ladders Detector fiducials relative to beryllium notches Transverse offset from nominal (μm)

25. Rise Time Studies Use LASER to excite SSD, Monitor preamp

26. Production Testing • HDI Burn-in • Encapsulation • HDI Spot-check • Ladder assembly • Ladder Spot-check • Ladder repairs • Ladder burn-in • LASER Test • Insertion into detector

27. Laser TestingChannel uniformity

28. Laser TestingChannel Gains

29. Ladder and HDI

30. Summary • We have achieved: • low mass flex/beryllium hybrids • SVX II chip, 53 MHz readout • Minimal dead area • Precise construction • A workable double sided design for “moderate” radiation doses • Now we just have to build another 787,968 channels