1. Endcap Systemtest • Current Grounding/Shielding status • Recent Upgrades to sector • Measurements with 6 Modules • Basic performance • First tries at noise injection • Plans J.Pater - Systemtest Report

2. Three Grounding Schemes • All 3 schemes have: • continuous shielding VME crate to Cu sector enclosure, • (~) all power lines AC connected to shield at PPF1, • system of interconnected foil rings on disk face. • Differences: • “Shunt Shields In” • Built-in shunt shields on module + isolation layer on cooling block • all modules’ DGNDs connected to shield at PPF0 • “Shunt Shields (~) Shorted” • Shunt shields still there but electrically bypassed • DGNDs not connected at PP0 • “Doubleshort” • Shunt shields ‘shorted’ • DGNDs connected together at PPF0 • All 3 schemes perform equally well with no noise injected J.Pater - Systemtest Report

3. Measurements with 3 Modules J.Pater - Systemtest Report

4. “Shunt shields in” (black) vs. “Shunt shields shorted” (red) “DoubleShort” scheme (Note different vertical scale) Injection onto Tapes J.Pater - Systemtest Report

5. “Shunt shields in” (black) vs. “Shunt shields shorted” (red) “DoubleShort” scheme (Note different vertical scale) Injection onto Pipes J.Pater - Systemtest Report

6. Ground Scheme Comparison with3 outer modules: Summary • A hybrid G&S scheme seems to work to best against injected noise: • Short around shunt shields i.e. DC-connect all GNDs together at cooling circuit • Also connect all DGNDs together at PPF0 • NB this is based on one measurement; needs verification. J.Pater - Systemtest Report

7. July/Aug: Upgrades to System • Now can simultaneously read out 6 modules of different types • Many problems with connectorised power tapes and Molex patch panels • Shielding improvements: • Added missing filtering caps at PPF1 (Vdd-shield, Vcc-shield) • Improved screening of 50m tapes • Added Cu sheet PPF1-thermal enclosure; used to improve interconnection of cable shielding J.Pater - Systemtest Report

8. 6 Modules on Sector Position O11 not working Back of disk: one module in position M10 J.Pater - Systemtest Report

9. 6-Module Run, no noise injection Blue = in test box at institute Yellow = alone on sector Purple = 6-module run J.Pater - Systemtest Report

10. 6 Modules, noise injection onto cooling pipes (shunt shields in) • Little or no pickup on inner and middle modules • More pickup on outer modules than before • Not understood, but… • … electrical connection of cooling pipes to outside world is not well simulated in systemtest – needs improvement J.Pater - Systemtest Report

11. 6 Modules, noise injection onto power tapes (shunt shields in) • Injected similar signal as in 3-module case • no pickup seen (!) • Injected MORE • very little pickup seen (see plot to right ) • Recall grounding/shielding improvements: • more filtering at PPF1 • better shielding and connections between PPF1 and sector box • Recent work suggests that the solidity of the electrical connection between PPF1 and the thermal enclosure is crucial. J.Pater - Systemtest Report

12. Near-future Plans • Upgrades: as soon as is practical: • Make cooling pipes’ exit from thermal enclosure more realistic • Install new on-disk tapes, PPF0s • (provided initial tests show satisfactory performance) • Repeat injection with all 3 G&S schemes • To verify previous observations with outer modules • To see what happens with middles and inners • If “doubleshort” scheme still best: • Remove shunt shields from modules to verify that it is not needed. • Address what to do electrically at cooling block. • Check: is pickup ~simply function of proximity to tape? • Test other outer positions, upper and lower • Vary distance silicon-to-tape. Need add-on for cooling block. J.Pater - Systemtest Report