1. The latest n-XYTER Test Results Krzysztof Kasiński (AGH Kraków) CBM Collaboration Meeting 26.02.2008 cincian@o2.pl Acknowledgements: Paweł Gryboś, Robert Szczygieł (AGH, Cracow) Adam Czermak, Bogdan Sowicki (INP, Cracow)

2. Presentation Outline  Hardware & Software  Uniformity Measurements Front-End gains Thresholds  Comparator Threshold Correction  Timestamp Resolution Analysis  First Acquisitions With Si Detector  Laser diode  Strontium Sr90  Summary CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

3. Sucima Imager DAQ board + n-Xyter Mainboard USB 2.0 Virtex 2 FPGA I2C LVDS 2 n-Xyter ASICs AC coupled detector Heatsink Absolutely required! > 150 *C ~70 *C Monitor & test pins Detector bias CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

4. ASICs and Detector topbottom Heatsinks Required! >90 *C ~50 *C Silicon detector 128-stripes AC-coupling 75 um pitch 1 cm length Several channels left floating CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

5. The Software layer CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

6. Uniformity test - thresholds floating inputs connected to detector CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

7. Uniformity test - thresholds CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

8. TrimDAC test Coverage: 19.42 LSB Step: 0.69 LSB CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl threshold correction

9. After the threshold correction... CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

10. After the threshold correction CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl 2.1771 0.432 2.0909 0.412 2.6861 0.352 2.2021 0.499 Threshold [reg.value]

11. Timestamp resolution – sources of errors Ideal case: Non-equal delays: Duty cycle different than 50%: Solution: programmable delay buffers: CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

12. T1 analysis disproportion due to the duty cycle =51.17% The best configuration 1 Region 1 Region 2Region 3Region 4 CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl 10% of events will have an error on T1 bit

13. disproportion due to the duty cycle =49.3% optimal configuration T0 analysis Region 1 Region 4 Region 2Region 3 CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl 7% of events will have an error in T0 bit

14. Laboratory set-up detector bias impulse generator Sucima Imager n-XYTER mainboard Detector daylight coverage & Laser Diode emmiter (replacable by the radiation source) CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

15. Preliminary results with a detector - Background radiation / noise - Noise cut-off at ~16 [reg.val] CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

16. Preliminary results with a detector Only a functional test of a detector + n-XYTER Pulsed laser diode directed at detector - configurable impulse length (from 20ns) - configurable number of impulses per second - possible manual triggering (sending certain number of impulses) CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

17. Strontium Sr90 first acquisition -37 hours of acquisition - ~37000 events-per-channel (total) - detector polarized by 135V - still too small statistic CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

18. Sr90 threshold scan results Non-conclusive! (due to varying source strenght and threshold spread) CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl *For figure clarity three most deviated channels were removed Threshold [reg.value]

19. Sr90 acquisition – spacial radiation strength not connected not connected masked corrupted channel More counts due to the larger active area created by adjacent not connected stripes general source radiation characteristic CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

20. Sr90 treshold scan results After correcting for the source spacial radiation characteristic the channels can be compared *For figure clarity three most deviated channels were removed CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

21. Sr90 threshold scan results CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl averaged counts for all channels (without most deviated ones) Derivative obtained using central difference formula ? Threshold [reg.value]

22. Summary  Optimal register values are still unknown  Comparator Threshold correction works fine  Timestamp resolution:  Bit 0: correction range wide enough, 7% error rate  Bit 1: not possible to fully compensate, 10% error rate  Measurements with detector:  Laser Diode Exciter proved that the full set-up operates properly  Strontium Sr90 – only preliminary measurement  Not enough statistic  Due to the spectrum spread it is not possible to calibrate the system  To Be Done in a near future: - Calibration using other radiation sources (with discrete energy spectrum)s CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

23. Treshold correction summary  Standard deviation before and after correction: A:2.1771 0.432 C:2.0909 0.412 B:2.6861 0.352 D: 2.2021 0.499  Expected values before and after correction: A: 85.32 96.99 C:84.46 96.42 B:85.72 96.35 D:85.66 96.51  Expected values spread improvement: 1.26 -> 0.64 (p-p)  TrimDAC current range is vast enough to successfully correct all channels (range: 19.42, step: 0.69 treshold bins)  The resolution of correction can bring down the standard deviation of the tresholds below one treshold bin CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

24. Threshold DAC characteristic CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

25. Sr90 threshold scan results Too small statistic! not-conclusive (nevertheless, a hump is visible) CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl Threshold [reg.value]

26. AFE gain Settings [reg values]: Icg=255 Vbfb=47 Icg_foll=255 VbiasF=0 iComp=62 iTwc=75 iInv=37 Positive pulse PRELIMINARY MEASUREMENTS still optimal values are unknown CBM Collaboration Meeting 26.02.2008 Krzysztof Kasiński (AGH Cracow) cincian@o2.pl

27. Settings [reg values]: Icg=137 Vbfb=0 Icg_foll=49 VbiasF=77 iComp=62 iTwc=75 iInv=37 Positive pulse