5 November 2002J.Pater - Systemtest Report1 Endcap Systemtest Current Grounding/Shielding status Recent Upgrades to sector Measurements with 6 Modules –Basic performance –First tries at noise injection Plans

5 November 2002J.Pater - Systemtest Report2 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

5 November 2002J.Pater - Systemtest Report3 Measurements with 3 Modules

5 November 2002J.Pater - Systemtest Report4 Injection onto Tapes “Shunt shields in” (black) vs. “Shunt shields shorted” (red) “DoubleShort” scheme (Note different vertical scale)

5 November 2002J.Pater - Systemtest Report5 Injection onto Pipes “Shunt shields in” (black) vs. “Shunt shields shorted” (red) “DoubleShort” scheme (Note different vertical scale)

5 November 2002J.Pater - Systemtest Report6 Ground Scheme Comparison with 3 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.

5 November 2002J.Pater - Systemtest Report7 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 (V dd -shield, V cc -shield) –Improved screening of 50  tapes –Added Cu sheet PPF1-thermal enclosure; used to improve interconnection of cable shielding

5 November 2002J.Pater - Systemtest Report8 6 Modules on Sector Position O11 not working Back of disk: one module in position M10

5 November 2002J.Pater - Systemtest Report9 6-Module Run, no noise injection Blue = in test box at institute Yellow = alone on sector Purple = 6-module run

5 November 2002J.Pater - Systemtest Report10 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

5 November 2002J.Pater - Systemtest Report11 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.

5 November 2002J.Pater - Systemtest Report12 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.