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Radiation induced leakage current in CMS TK slilicon sensors

Radiation induced leakage current in CMS TK slilicon sensors. Christian Barth, Alexander Kainskiy Many thanks to Gino, Frank, Franz. 1. First indication of Ileak increase du to radiation. 2. The scope of this presentation. Since we do see an effect, let’s agree on

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Radiation induced leakage current in CMS TK slilicon sensors

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  1. Radiation induced leakage current in CMS TK slilicon sensors Christian Barth, Alexander Kainskiy Many thanks to Gino, Frank, Franz ... 1

  2. First indication of Ileak increase du to radiation 2

  3. The scope of this presentation • Since we do see an effect, let’s agree on • Which data samples to use: • last datapoint of Ileak from database within 10 minutes after stable beam is declared, having Vmon > (250V ? ) • Deadbanded • option – the same but in cosmic runs • option – make dedicated snapshots, but it seems a bit overkill • Where to take the delivered lumi • I found a table which contains delivered lumi, 1 record per fill, starting from 13/03/2011. Looks like it archives DIP messages coming from ? • Maintained by ? Is it corrected in case of Dip/lumi problems? • Which corrections/compensation/normalization is needed? • Do we need some additional calibration (DCU, etc) ? • What kind of monitoring is needed and how often? 3

  4. There is a table CMS_BRM_COND.FILL_SUMMARY Which contains delivered lumi starting from 13/03 4

  5. Before looking at histograms… • We have to take into account: • Volume of the supplied silicon, geometry • easier for Barrel, more difficult for the EndCaps • Temperature effects/compensation/normalization • uncooled power groups, detached modules • SS and DS modules • HV1 and HV2 may have different number of connected modules • by design ( f.ex. TIB L3 and L4) • Removed jumpers • Pathologies (leaky modules, “bad” or saturated PSUs) • History of interventions becomes more important! • RELIABLE DCU DATA ARE MANDATORY ! 5

  6. Tools • Online (web based) • Tool which allows plot Imon vs time and vs Lumi for single power supplies • Offline • Script which retrieve Imon vs Lumi for substructure (f.ex. TIBminus_1) • Simple root script to Fit and fill the histograms • DCU tools (online and offline)

  7. Example of pathologies 7

  8. DCU map: Ileak during global run 27/04 Color scale is from 1.3 to 20 (uA?) Looks a bit noisy 

  9. DCU map: silicon temperature during global run 27/04 Color scale is from 5 to 40 C Looks much better then Ileak, but still has many otliers

  10. DCU map: Ileak difference between 27/04 and 15/03 Color scale is from -1 to 5 C Integrated luminosity is ....pB

  11. TIB Layer 1 11

  12. TIB Layer 2 12

  13. TIB Layer 3 13

  14. TIB Layer 4 14

  15. TID 15

  16. TOB Layer 1 16

  17. TOB Layer 2 17

  18. TOB Layer 3 18

  19. TOB Layer 4 19

  20. TEC 20

  21. Barrel Pixel Layer 3 21

  22. Barrel Pixel Layer 1 (and 2) 22

  23. Forward Pixels 23

  24. Summary Work ongoing to normalize experimental leakage current increase with the DCU TSIL temperature readouts. (Christian)

  25. Conclusions Discussion • We have measurements of IleakvsLumi • Possibility to setup right thresholds for CAEN system • There are simple tools to check and retrieve necessary data: • a good starting point for a more sophisticated analysis • we have to monitor that data are in DB (how?) • Better temperature compensation • Module by module • DCU calibration • Ileak from DCU • Reliability of DCU data • DCU calibration (urgent!) • TEC and TID geometry and HV grouping • Simulations • Who continue/supervise this task?

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