1. Leo Greiner 2007-05 IPHC1 STAR Vertex Detector Environment with Implications for Design and Testing

2. Leo Greiner 2007-05 IPHC2 Talk Structure Context and overview Mechanical Material Budget, Radiation Length and design implications. Testing Plan – present and future

3. Leo Greiner 2007-05 IPHC3 HFT inside STAR TPC ~1m Inside the TPC Active length ~20 cm HFT R1 = 9 ladders @ 2.5cm R2 = 12 ladders @ 6.5cm R3 = 12 ladders @ 7.5cm SSD IST

4. Leo Greiner 2007-05 IPHC4 Direct Topological reconstruction of Charm Detect charm decays with small ct, including D0  K  New physics Charm collectivity and flow to test thermalization at RHIC C & B Energy Loss to test pQCD in a hot and dense medium at RHIC Method: Resolve displaced vertices (100-150 microns)

5. Leo Greiner 2007-05 IPHC5 Tracking Resolution by Layer (simulation with MCS) –Goal: graded resolution from the outside  in –TPC – SSD – IST – HFT (single track pointing, without a vertex constraint) –TPC pointing resolution at the SSD is ~ 1 mm –SSD pointing at the IST is ~ 300  m –IST pointing at the HFT is ~ 250  m –HFT pointing at the VTX is ~ 30  m

6. Leo Greiner 2007-05 IPHC6 Conceptual Mechanical Structure Three main requirements drive the design. 10 µm stability for the location of the pixels. Very low radiation length (stiff low mass / z structures). Fast replacement of detector assemblies without rolling out STAR detector or resurveying.

7. Leo Greiner 2007-05 IPHC7 Main Mechanical Structure Solid model of conceptual design Close up (beam pipe removed) of Low mass region and sensor ladders 33 ladders on 3 removable sections -1 < eta < 1 (20 cm active length)

8. Leo Greiner 2007-05 IPHC8 Prototype Ladder 2 candidates Top layer = 50 µm CFC Middle layer = 3.2 mm RVC Bottom layer = 50 µm CFC Outer shell = 100 µm CFC Fill = RVC APS (50µm) X 0 = 0.05 % (thinning to 50µm is a standard industrial process) Cable X 0 = 0.09 % (4 layer Al conductors on 25 µm Kapton) Carrier X 0 = 0.11 % Ladder Total (with adhesive) X 0 = 0.282 % (no discrete components) Not to scale * Atlas pixels are X 0 = 1-1.5% DESIGN GOAL X 0 < 0.5% / layer Carrier Composition

9. Leo Greiner 2007-05 IPHC9 Mechanical Prototype Testing 80mW / cm 2 Heater cable 50 um Si Air Cooling Position Distribution Histogram

10. Leo Greiner 2007-05 IPHC10 R-Phi Position Resolution X 0 = 0.28 % / layer X 0 = 0.56 % / layer

11. Leo Greiner 2007-05 IPHC11 X 0 contribution by discrete components 0201 capacitors – 0.51 mm x 0.25 mm x 0.25 mm with 0.075 mm solder stencil. Up to 0.1 µf @ 6.3 V. “A” tantalum capacitors – 3.2 mm x 1.6mm x 1.6 mm with 0.125 mm solder stencil. Up to 47 µf @ 6.3 V.

12. Leo Greiner 2007-05 IPHC12 Discrete Components Area Layout and X 0 contribution Discrete components 1.6 mm x 200 mm in low mass region Analog and Digital drivers Mimostar Sensors With 4 x 0201 ceramic capacitors / sensor, 1 x “A” tantalum capacitor / sensor X 0 SolderX 0 componenttotal 0201 in shaded region0.03 %0.014%0.044 % 0201 averaged over detector0.0024%0.0011%0.0035% “A” in shaded region1.35 %5.39%6.74% “A” averaged over detector0.108%0.431%0.539%

13. Leo Greiner 2007-05 IPHC13 Sensor Environment in STAR Only 0201 components in low mass region. Sensors thinned to 50 µm. Mounted to low mass readout cable with Aluminum conductors. Power and Ground common to all sensors. Multidrop LVDS clocks. Multiple sensor operation / interactions.

14. Leo Greiner 2007-05 IPHC14 Sensor Testing Mimostar2 – Sensor Architecture prototype. Many test points, bias and signal output structures. Validate design process and simulation. Test sensor performance vs. simulation in best possible conditions. Knowledge gained feeds into Mimostar3 design.

15. Leo Greiner 2007-05 IPHC15 Sensor Testing (cont.) Mimostar3 – Preproduction design. Same padring as final sensors. Asses performance in ideal environment. Asses performance in STAR implementation environment including multiple sensor interaction. (this implies a test “ladder” of Mimostar3 sensors on a low mass cable) Asses yield. Knowledge gained feeds into Mimostar4 design.

16. Leo Greiner 2007-05 IPHC16 Sensor Testing (cont.) Mimostar4 – Production design. Final padring and final sensors including fiducial marks. Asses performance in ideal environment. Asses performance in STAR implementation environment including multiple sensor interaction. (this implies a test “ladder” of Mimostar4 sensors on a low mass cable) Asses yield. Knowledge gained allows for full order of wafers or next generation.

17. Leo Greiner 2007-05 IPHC17 Components Needed for STAR Implementation Test Environment Mimostar 3 – Test cable developed jointly to optimize both sensor and cable design within the constraints imposed by the STAR environment. Parameters such as capacitive filtering and bypass, analog readout signal integrity, clock distribution, sensor interaction, etc. to be investigated and optimized. Full multi-sensor ladder tests. Mimostar4 – Final readout cable with Aluminum conductors. Complete ladder testing.

18. Leo Greiner 2007-05 IPHC18 Test Assembly Proposal LBNL and IPHC collaborate and agree on cable prototype design. LBNL procures cables. LBNL thins sensors to 50 µm and uses techniques developed for ladder fabrication to assemble multi-sensor ladder prototypes. Prototypes are tested at LBNL and IPHC.

19. Leo Greiner 2007-05 IPHC19 Yield Issues Post probe test assembly of ladders is a complex and multifaceted process. We are interested in the “final” yield of complete working 10 sensor ladders. This drives the number of wafers required for a complete detector set. Some significant number of working Mimostar3- 4 sensors will be required to troubleshoot and validate this assembly sequence as well as to test chip performance on ladders in low radiation length environment.

20. Leo Greiner 2007-05 IPHC20 fin

21. Leo Greiner 2007-05 IPHC21 Relative efficiency for single tracks (solid) and a crude estimate for D0 efficiency (dash)