2. Introduction  Goal: Study noise occupancy of the FE-I4B chips on the quad-module mounted on the stavelet with serial power  About one month ago, observed unexpected increase in noise  How we trace down the problem  Latest noise scan results after fixing the problem  Cross check between USBpix and RCE

3. Stavelet For more information on the Stavelet : https://indico.physics.lbl.gov /indico/conferenceDisplay.py ?confId=210 https://indico.physics.lbl.gov /indico/conferenceDisplay.py ?confId=210 -Mount 5 Quad-Modules on Stavelet -The Modules are serial powered

4. USB Pix and HSIOUSB Pix and HSIO -Software for USB Pix: Stcontrol USB PixHSIO -Software for HSIO: Calibgui -Works with RCE

5. High Noise Problem on RCE. And Solution

6. Original ProblemOriginal Problem Ran scans with same settings. Only ran scans at different dates. Presentation: https://indico.physics.lbl.gov/indico/getFile.py/access?contribId=0&res Id=0&materialId=0&confId=210 BeforeAfter

7. Early StudiesEarly Studies -Checked Noise Occupancy under many different conditions to find out where the high noise is coming from -One of the lesson that we learned is that we had to put the temperature under control -At some point the suspicion is that the high noise is from the unstable grounding on the stavelet -We soldered wire jumpers between all module positions but it did not solve the problem.

8. Comparison RCE (HSIO) vs USBPix RCE USBPix Temperature, powering, and tuning stayed the same.

9. Solution to Decreasing Noise  Fixed from where the HSIO was being powered from.  Instead of 110V we changed it to 12V

10. Updated Results from HSIOafter Problem Fixed  Noise appeared in the HSIO system. Old PlotNew Plot

11. Temperature for the Noise Scan Threshold varying from 100 to 60

12. NOISE: RCE vs. USBpixNOISE: RCE vs. USBpix  Measuring noise occupancy using USBpix/Stcontrol as cross check to results from RCE/calibGui based on identical tuning  Scan FE1 on LBLQ1 on Stavelet with water temp. 15C  Trigger rate=0.5MHz, trigger multiplier=1  USBpix/Stcontrol needs 20~30 more time to accumulate the same amount of events as RCE/calibGui: Any hint for the reason?  Accumulate ~30M events for USBPix/Stcontrol ~[30 minutes]  Accumulate~300M events for RCE/calibgui ~[10 minutes]

13. Noise occupancy: RCE vs USBPix RCE USBpix Very similar behavior -Noise busrt at AltFine = 60 -Right half of the chip noiser at low threshold -Similar noise patter for ganged pixels and hot pixels

14. Noise occupancy: RCE vs. USBpix Apply same mask to remove ganged/hot pixels USBpix consistently yields higher noise occupancy than RCE -Seems missing a constant scale factor -Different counting method for number of triggers?

15. Scanning AltFine : Low  High vs. High  Low Used to observe difference between scanning Altfine high  low and low  high

16. SCANNING: Low  High vs High  Low  The discrepancy is now gone  -Previous observation probably affected by unstable grounding of HSIO

17. Conclusion and Next StepsConclusion and Next Steps  The chip was very noisy when we used the HSIO system.  The wire that was supplying the power was unstable. USBPix output more noise than RCE. But they have similar evolvement in Noise Occupancy. It could be the software or hardware. Next Steps: Study Noise Bursts Since, the USBpix detects higher noise occupancy than RCE we want to find the reason why that happens.

18. Backup

19. Temperature for the Threshold Scan Temperature for the Threshold Scan

20. Source Scan of Q1Source Scan of Q1

21. Stability of the Noise Critical Point under different rate and trigger multiplier This study was done around the time point the problem occurred and it is repeated now that it is fixed.