2. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The thermal screen grounding and the tracker: a scary concert Enzo Carrone

3. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The stage T in < -10 o C T out +18 o C Carbon Support Tube (CST) Faraday cage: 100 μm thin external coating (facing ECAL). The Faraday cage performance depends on the quality of its connection to the zero-voltage reference point of the device to be screened.

4. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone Section view Cold plate: 2 aluminum panels welded together Heating foils: capton with Inconel PCB. 0.79 A @ 48 V DC Insulating layer: Rohacell ® panel TOTAL THICKNESS : 13 mm 16 + 16 Panels, 21° coverage each

5. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone Detailed layers view CKCK C ST

6. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The music hall

7. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The partitions  Heating panel (Inconel ®) (16 independent panels per side, each one spanning over half Tracker length) Surface:0.8 m 2 Power density: 114 W/ m 2 Current absorption: 0.79 A @ 48 V DC  Insulating layer (Rohacell ® 51 IG) Thermal conductivity: 0.039 W/mK  Cooling panel (0.7 mm thick Aluminum foils welded to form spiral shaped pipes) C 6 F 14 flow rate per panel: 194 - 302 Kg/h Flow speed in the panels: 0.63 - 0.98 m/s Number of panels served by a  11 feeding pipe: 2 Flow speed in the feeding pipes: 0.65 - 1.03 m/s

8. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone LV Power Supply Ethernet LAN Siemens PLC Heating foils The musicians Temperature, Relative Humidity Analog regulation HMI Pt 100

9. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The rules Structure earth is a safety environment. Circuit earth is a conditional safety requirement.

10. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone Grounding

11. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The conductor Output Voltage Output Current Output Power 0-120 V 0-4.5 A 540 W Output Noise Voltage (p-p, 20 MHz bw) 150 mV Output Ripple (rms, 100 kHz bw)) Voltage Current 20 mV 75 mA Xantrex XPD 120-4.5 Who defines the zero-volt reference? If we tie it to the Tracker, would the ECAL noise pass through it? Safety issue : the PS is -not- double insulated: it must be protected against direct contact.

12. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone Thermal Screen Electric Noise Orchestra The Thermal Screen behaves as a resistive structure for Low Frequencies. From MF to HF, this is not true anymore: it will show a big capacitance. We have noise coming from both the ECAL and the Tracker side. The tracker side is likely to show more immunity, though.

13. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone Power Supply noise philharmonic In order to overcome it, we can put a filter in between the PS cable and the TS. 100 m of cable already show a 10÷100 μH up to 100 Mhz. The cable itself is already a filter! Control power supplies will be installed ~100 m away from the detector: they use switching technology → the noise generated will be radiated on the way by the cables.

14. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone The PLC noise trio 1) Input impedances do not change on power on/off 4) Input is fairly symmetric 6) Magnitude measurement is done up to 40 MHz. 7) Smith diagram from 9k to 100MHz. Cursor position @ 10 Mhz means the diagram is concentrated in a very small domain close to the infinity point. For the ground loops fear this is a non-event.

15. Thermal Screen Grounding CERN - Dec. 10 th, 2003 Enzo Carrone Conclusions – is the entrance free? Is the thermal screen a viable solution as for the Tracker grounding? We can start thinking about! Well... 1. It is a metal structure which fully surrounds the Tracker. 2. It is probably the biggest uniform structure available. 3. The various systems can connect wherever, in many points (thus creating a distributed ground architecture). …But don’t forget the general CMS ground.