1. EMC review for Belle II (Grounding & shielding plans) PXD system - July 2012 Dr. Fernando Arteche

2. Outline 1.Introduction 2.Grounding strategy –Topology –Implementation aspects 3.Noise emission –Test plans 4.Noise immunity issues –Signal circuit –Test plans 5.Cabling 6.Conclusions 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 1 de 20

3. 1. Introduction PXD- DEPFET detector is very complex FEE (Sensor, DCD,DHP) –It may be sensitive to EM noise –It may radiates ( HF clocks and signals) Power supplies It emits EM noise Cable & connectors It may propagate EM noise inside/outside FEE area 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 2 de 20

4. 2. Grounding strategy What is a ground ? –It is a reference Uniform reference voltage at any frequency –It is a structure to bypass currents Fault (short circuits..) Noise Reasons for Grounding –Safety –Equipment protection –Equipment performance Golden rule: –“Make the system safe and then make it work ” 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 3 de 20

5. 2. Grounding strategy Selection of reference –Any metal structure – Local GND (Cooling blocks) It should have low impedance from DC to High frequency Safety ground & Equipment protection –Ground path should be free of operational currents –Laboratory codes and standards at KEK - Any ? Metal parts that can be energized – should be grounded Ground connections - Bonding and straps –An EMC program has been implemented for the machine EMC PROGRAM ON THE ACCELERATOR RINGS –K. Okamura (KEK), Y. Watanabe (JAEA) It is mainly focused on grounding issues only –¿ Should we apply the same rules ? 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 4 de 20

6. 2.1 Grounding strategy - TopologyPXDDetector Prefered option: Multipoint (Hybrid) ground 5 de 20

7. PXD connected to the cooling blocks –AGND-DGND: Connected at 1 point locally to cooling blocks ( where and how ?? ) DC or AC (it should be controlled – depends on frequency Ampl.) Cooling blocks (both sides) connected via low impedance Cooling pipes grounded PXD local ground connected to experiment ground 2.1 Grounding strategy - Topology Experiment GND – Where? Cooling pipes IsolationAn.& Dig gnd CB Detector (FEE) 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 6 de 20 An.& Dig gnd

8. 2.2 Grounding topology: Grounding implementation – Capacitors & straps Structures, boards and cables will be connected via straps Long straps should be avoided Capacitors are required to decouple the power feeds (filtering) and (in case necessary) provide an AC connection to ground. They have to be prepared to operate at High-frequency, 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 7 de 20

9. 3. Noise emissions Main external noise sources for PXD will be : –Conducted: Power supplies - Switching power converters CM currents from neighboring systems Via power cables – Power cables most critical path due to low impedance Via conductive ground structures –Radiated noise Inside SVD + PXD volume (carbon fiber shield) –No many far field emissions are expected because distance and frequency. (f=100 MHz - λ =3 m ) –Near field - Magnetic field noise emissions : predominant »High currents and low impedance paths Outside –Only cables may introduce some noise »It becomes a conducted noise phenomenon 8 de 20

10. PS system of PXD is very complex – (23 voltages) –Power is supplied remotely by several floating DC-DC converters (7) This PS emits noise 3. Noise emissions DEPFET VOLT DCD VOLT Switching converters generates conducted noise At the input & output Two modes of noise emissions (kHz - MHz range) Common mode & Differential mode 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 9 de 20

11. 3.1 Noise emissions: Test plans Detailed test plan is planned to measure the noise emission level of the power supply units –It will help to define the compatible levels with the FEE. Special setup will be required –Special connectors and cables –Test load - A set of resistors Electronic loads are noisy. It will be measured the noise emissions at input and output –EMI probes and spectrum analyzers This test is planned for: – September or October 2012. 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 10 de 20

12. 4. Noise immunity issues The immunity of the system is defined main by the sensitivity of the FEE –Other system may be affected by noise but based on previous experience, signal circuit is the most sensitive one. Two noise may disturb the performance of FEE –Thermal noise dominant effect (by design) –EM external noise (via power lines, FEE-det, etc) EM noise contribution depends on two factors –It depends on Front End Amplifier frequency response. –Coupling mechanisms (coupling network) Signal circuit 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 11 de 20

13. The most important elements of the input signal circuits are: –Trans-impedance amplifier Low Gain ( 1,2,3 or 4) –It is an advantage for PXD !!! –Impedances associate to this circuit Real & stray 4.1 Noise immunity issues: Signal circuit 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 12 de 20

14. 4.1 Noise immunity issues: Signal circuit Equivalent signal detection circuit 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 13 de 20

15. The characterization of EMI contributions due to external noise is performed via immunity test on prototypes Weak points & noise characterization Compatibility among subsystems The idea is to inject noise into the system via external lines. Different frequencies and amplitudes This measurement will define the transfer function between noise and FEE output. 4.2 Noise immunity issues: Test plans TF – [Counts / mA] Frequency – [Hz] 14 de 20

16. 4.2 Noise immunity issues: Test plans Two sets of test are planned: –First set of immunity tests will be performance on a prototype system of DEPFET – Hybrid 4.1.XX It is planned for end 3Q2012 at University of Bonn. –Second set of tests are planned on a full prototype of DEPFET system (EMCM or / and Hybrid 5.0.XX) Full system operation. It is planned for 2013 at ITA facilities 12 3 15 de 20

17. 5. Cabling PXD have a complex topology for cabling the sub-detector. –These cables are very different(Voltages, Currents,Signal, Power) Attention should be paid in the cabling coordination because it may lead to some integration problems. –Interference phenomena & Transient effect Cables golden rules: –Classification Class A- DC-DC converters.. Class B- DC & AC distribution bellow 1 kV, control circuits Class C- Signals (analogue, low rate digital) Class D – Signals (low analogue, high rate digital, sensitive). –Layout Distance between cable class : –10 and 30 cm This distance may be reduce using: – Shields and filtering techniques 16 de 20

18. 5. Cabling There are three types of cables: –PS – Junction box : Type 1 – (15m) –Junction box – Patch panel: Type 2 (2 m) –Patch panel – Detector : Type 3 (≈ 0.5 m) 1 2 3 17 de 20

19. 5. Cabling Patch panel Junction box Power & Data (Kapton cable) Power & sensing (no inner shields) Data (Paralink cable) Power & sensing (inner shields) Module (DCD-DHP) Data (paralink cable ) DHH Power supplies & Slow control Optical fiber ( DAQ, Trigger & timing) Power Slow control 15m2 m 0.5 m 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 18 de 20

20. 5. Cabling Cable shields will help to minimize the coupling among cables. –Shields connection should be carefully analyzed Golden rule : Connect shields both sides at HF. Some studies and measurements are needed to define the key parameters of power network. The studies and analysis will be based on: –Numerical models developed in MATLAB codes. It will help to address the effect of power cables on the noise propagation and the impact that those cables have in the selection of: –EMI filters for the FEE low-voltage input –Conducted emission levels required for the power supplies. –Shielding connection 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 19 de 20

21. 6. Conclusions PXD-EMC plan has been presented First analysis of the grounding system has been presented. Still some questions remain open –Some of them depends on other subsystems –Some of them depends on the analysis of EMC test A detailed and specific test campaign is plan for end 2012 and 2013 –Conducted emission test September or October 2012 –Immunity test 3Q 2012 2013 12th Open Meeting of the Belle II Collaboration July 21-26, 2011, Bad Aibling, Germany 20 de 20