1. And now for something completely different First results from the DC-DC Stavelet Peter & Ashley with Giulio & John

2. DC-DC Stavelet First Module 2

3. Unstuck? Power ON Power OFF SE4445 is used to attach modules to stavelets. At room temperature, this takes a long time to cure. When the module was first powered, it bowed as shown. It’s not quite as bad now, but it does still bow. Do we need to remove and re-attach this module or is it OK to leave it? If we use SE4445 for further modules, do we need to allow a longer cure before application of power? H0 H1 3

4. Chip & Strip Numbers 32333435363738394041 64656667686970717273 BCC Edge DC-DC Edge Channel 0Channel 1279 Strictly, the hardware channel numbering is contiguous only for the upper column. Chip 64 for example has channel 127 at the sensor edge – but in all plots which follow this has been corrected in software to match the above labels. 4

5. Shield Connections (IN USE) Shield Connection (NOT IN USE) Backplane Connection (H1 only) Shield Referencing Option to Link LVDS & Sensor Shields 5

6. H0 Original Shield H1 Original Shield Both hybrids at Once H0 Original Shield H1 Unpowered H0 Unpowered H1 Original Shield 10/06/2011, 10V 3.0A limit, H0 DC referenced to shield, H1 AC referenced to shield H0 Outer Column H0 Inner Column H1 Inner Column H1 Outer Column ENC Measurements Ch 0 -> by BCC Ch 1279 -> by DC-DC 6

7. 10/06/2011, 10V 3.5A limit, H0 DC referenced to shield, H1 AC referenced to shield H0 Wrapped Shield H1 Wrapped Shield Both hybrids at Once H0 Wrapped Shield H1 Unpowered H0 Unpowered H1 Wrapped Shield ENC Measurements Ch 0 -> by BCC Ch 1279 -> by DC-DC 7

8. Cursory investigation of B field along axis through converter centres 0 5 10 cm Converter PCB now closer to the hybrid edge than for the single module DC-DC tests (~2mm from ~7mm) and it’s also now in the same plane. Therefore the scope for pickup is increased. 8

9. HMS3000 Typical Screenshot 9 Shields wrapped in Cu tape, both converters running, 3cm point

10. Shields Removed both converters running Noise Floor cm dBm Not Calibrated: relative measurement only 10

11. Shields Removed H0 converter running, H1 powered down Noise Floor cm dBm Not Calibrated: relative measurement only 11

12. Shields Removed H0 powered down, H1 converter running Noise Floor cm dBm Not Calibrated: relative measurement only 12

13. Shields Wrapped in Copper Tape both converters running Noise Floor cm dBm Not Calibrated: relative measurement only 13

14. Shields Wrapped in Copper Tape H0 converter running, H1 powered down Noise Floor cm dBm Not Calibrated: relative measurement only 14

15. Shields Wrapped in Copper Tape H0 powered down, H1 converter running Noise Floor cm dBm Not Calibrated: relative measurement only 15

16. Field leaks through gap between shield and converter PCB Will a “skirt” help? fitted over existing layer of copper tape H0 H1 Also revised hybrid referencing to make both DC referenced 16

17. Effect of “Skirt” on B field 17 These measurements were made using the smallest magnetic field probe placed immediately adjacent to the converter shield of hybrid H0 of the single DC-DC module M5 (not stavelet module M13). WITHOUT SKIRTWITH SKIRT

18. H0 Wrapped Shield H1 Wrapped Shield Both hybrids at Once H0 Wrapped Shield H1 Wrapped Shield One hybrid at a time H0 Wrapped + Skirt H1 Wrapped Shield Both hybrids at Once H0 Wrapped + Skirt H1 Wrapped Shield One hybrid at a time 18 21/06/2011, 10V 5.0A limit, Both hybrids DC referenced

19. H0 Wrapped Shield H1 Wrapped Shield Both hybrids at Once H0 Wrapped Shield H1 Wrapped Shield One hybrid at a time H0 Original Shield H1 Wrapped Shield Both hybrids at Once H0 Original H1 Wrapped Shield One hybrid at a time 19 21/06/2011, 10V 5.0A limit, Both hybrids DC referenced

20. TEST 1: 5.0A Wrapped Shields Both hybrids at Once TEST 2: 3.5A Wrapped Shields Both hybrids at Once TEST 3: 3.0A Wrapped Shields Both hybrids at Once TEST 4: 5.0A Wrapped Shields Both hybrids at Once 20 22/06/2011, 10V variable current limit, Both hybrids DC referenced

21. TEST 1: 21/06/11 Sensor Shield DC @ BCC edge Both hybrids at Once TEST 2: 21/06/2011 Sensor Shield DC @ BCC edge Each hybrid separately TEST 3: 21/06/2011 Sensor Shield DC @ both edges Both hybrids at Once TEST 4: 21/06/2011 Sensor Shield DC @ both edges Each hybrid separately Wrapped shields used throughout, TTi supply at 10V 5A limit

22. Double Trigger Noise @ 0.75fC 22 TTi TSX3510P @ 10V, wrapped shields, both hybrids at once (yes it really is this clean)

23. Double Trigger Noise @ 0.50fC 23 TTi TSX 3510P @ 10V, wrapped shields, both hybrids at once

24. Summary Increasing the TTi TSX3510P PSU current limit above 3.0A has no effect upon the ENC noise – Avoid values below this supply will not trip but may current limit Referencing changes have had a greater effect than increasing the mass of the shields – Extra 2 bonds per hybrid at DC-DC edge helped reduce the noise Beyond that, all that’s present in the design is the option to connect the sensor shield pad to the LVDS shield. Next : further reduce inductance of the shield connection – How can we improvise Cu or Al foil connections between Al shield and adjacent DC-DC power return line? See over for first attempt.... 24

25. Lowering the Inductance of the Shield Connection 25 1.Remove kapton tape from power bus 2.Partially remove kapton cover from sensor shield 3.Add a dozen bonds to connect them together =>Sensor Shield is connected directly to power GND

26. TEST 3: 21/06/2011 Sensor Shield DC @ both edges Both hybrids at Once TEST 4: 21/06/2011 Sensor Shield DC @ both edges Each hybrid separately NEW TEST 5: 29/06/2011 Sensor Shield DC & to power return Both hybrids at Once TEST 5: 30/06/2011 Sensor Shield DC & to power Return Each hybrid separately Wrapped shields used throughout, TTi supply at 10V 5A limit

27. Future Plans Continue to lower the inductance of the shield connection What if this does not work? ???? 27

28. Backup

29. Naked Converters! Converter 06: BC0000000476043AConverter 14: 7C0000000455D23A 29 Q) Does the precise physical orientation of each coil have any great significance?

30. 30 M13 Single Module Result (SP @ Liverpool) M13 Stavelet Best running both at once Wrapped Shields M13 Stavelet Best running one at a time Wrapped Shields