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ZDD installation and performance

ZDD installation and performance. BESIII Collaboration Meeting, December 2011 A. Calcaterra , for the ZDD group (LNF+TO). Talk outline. ZDD performance in Frascati, Spring 2011 Cosmic rays Single-electron beam ZDD installation, August 2011 ZDD tests with cosmic rays at IHEP, Fall 2011

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ZDD installation and performance

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  1. ZDD installation and performance BESIII Collaboration Meeting, December 2011 A. Calcaterra, for the ZDD group (LNF+TO)

  2. Talk outline • ZDD performance in Frascati, Spring 2011 • Cosmic rays • Single-electron beam • ZDD installation, August 2011 • ZDD tests with cosmic rays at IHEP, Fall 2011 • Outlook • Short term • Next weeks A. Calcaterra

  3. The ZDD in the East area Gearbox for minical movement Fiber bundles (2m) W screen γ beam axis ZDD: Pb/Sci.Fi Array, scintillating material 60% of total (in volume), two modules (up and down the beam) dimensions:14x4x6cm3 A. Calcaterra

  4. 1 5 4 3 2 6 10 9 8 beam 7 ZDD module segmentation 14 cm 4 cm Each sector is sent to a PM, sectors 1&2 (6&7) are sent to the same PM (for now) A. Calcaterra

  5. BTF test beam at LNF(may 16-22 2011) One (out of two) ZDD module tested at BTF with 450, ~300, ~200 MeV e- bunches (Ne-=1,2,3) Final Pb-scifi ZDD module, bundles guides, PM’s, TDC, at the moment not FADC but ADC caen V792N Small scintillator (60x11x4) mm3 used to trigger and select electrons impact point A. Calcaterra

  6. Setup in Cosmic rays (LNF) A. Calcaterra

  7. Setup in Cosmic rays Top “finger” scintillator, (11x5x50) mm3 Bottom “paddle” scintillator Trigger coincidence rate = (2-3 minutes)-1 A. Calcaterra

  8. Purpose of cosmic rays DAQ • 2 types of data taking: integrated charge (QDC CAEN V792N) and lineshape (Flash ADC CAEN V1721). Timing information is also present (TDC CAEN V1190) but not systematic. • QDC data used for: • inter-channel calibration • resolution studies • absolute scale, comparing cosmics to single-electron • FADC data used for MeV/mV calibration A. Calcaterra

  9. Run 224: QDC cts for each PM A. Calcaterra

  10. HV correction table for “up” calorimeter A. Calcaterra

  11. Find passing tracks (left side) A. Calcaterra

  12. 4Q passing tracks (“up” calorimeter) A. Calcaterra

  13. Absolute scale and E/E • According to Montecarlo a passing cosmic track leaves 16 MeV of energy in the scintillator • QDC scale (when “Happy Box” is used) is approximately 170 pC / 16 MeV = 11 pC / MeV. • For E/E we find 20/180 = 11%, consistent with simulation (no shower fluctuations). A. Calcaterra

  14. Number of photoelectrons • Assuming a PM gain ≈ 1.2·106, the number of photoelectrons per cosmic track is: • The factor 2 in the denominator is due to the “Happy Box” • Approximately 1/7th of these 443 p.e. develop in the first PM, 2/7th in each of the other 3 PMs A. Calcaterra

  15. Photoelectrons/MeV (cosmics) • According to Montecarlo 16 MeV are deposited in the scintillator by cosmic track, 50 MeV in all. This means: • 28 photoelectrons/MeV in the fibers (14 cm) • 9 photoelectrons/MeV in the whole calorimeter A. Calcaterra

  16. ZDD as a new luminometer(luminosity monitor) • Frascati cosmic ray test shows: • The time resolution is 0.97ns, which meets the requirement of a luminometer（<4ns） • The signal width is only 5.2ns, so dead time is very little. • The old luminometer on east side of BESIII was uninstalled and replaced by ZDD. • ZDD signal is fanned out as luminometer. The electronics and DAQ for luminometer are kept the same. • Tested by the noise, the new luminometer system is working properly. Its performance as a luminometer shall be checked under colliding mode of BEPCII. Slide by Xue Zhen

  17. Tests at the BTF Single-electron beam from Frascati Beam Test Facility trigger (6.0x1.1x0.4)cm3 finger scintillator • The BTF: few-electrons, 50Hz pulses from DAFNE Linac • Minicalorimeters rotated, fibers vertical • Trigger on AND of RF signal and «finger» • Data taken mostly with QDC (FADC electronics available only at the end of our beam time) A. Calcaterra

  18. Purpose of single-electron DAQ • Study response to single electrons of different energies • Study • resolution with single electrons • absolute scale factor, MeV/pC • photoelectron statistics • How does these data compare to cosmic-rays ones? A. Calcaterra

  19. QDC 8Q, 450 MeV, PM equalized 38.43/294 = 13% 36.84/296 = 12.4% A. Calcaterra

  20. Absolute scale • According to Montecarlo a 450 MeV electron leaves 12%·450 = 54 MeV of energy in the scintillator • If the absolute scale from cosmics is right, we should see 54 MeV·5.5pC/MeV=297 pC (“Happy Box” X2 preamp was not in use yet) • ….and we do! Perfect! A. Calcaterra

  21. Number of photoelectrons • Assuming a PM gain ≈ 1.2·106, the number of photoelectrons at 450 MeV is: • According to MC (12%·450 = 54 MeV deposited in the scintillator) this means 30 photoelectrons per MeV (28 in cosmics) • How are these divided among the strata? A. Calcaterra

  22. Run 4 at 450 MeV 32/300=10% 150/300=50% 86/300=30% 31/300=10% A. Calcaterra

  23. The ZDD installation war! Arrival at IHEP A. Calcaterra

  24. The ZDD installation war! A. Calcaterra

  25. The ZDD installation war! A. Calcaterra

  26. The ZDD installation war! A. Calcaterra

  27. The ZDD installation war! Thanks Mario and Zhen for a fantastic effort! A. Calcaterra

  28. Cosmic rays at IHEP • There is no external trigger • Auto-generated trigger: ≥2 out of 8 FlashADC channels must have a minimum below some threshold (baseline-3cts = baseline-12mV) A. Calcaterra

  29. Analysis still very preliminary • Fitting the waveforms we obtain for each channel a minimum and a time of minimum • Noise shows up mainly in 2-hits events (peak times differ randomly) • 3-hits events are much cleaner • …still, very difficult to define a passing track, due to the very small solid angle • No control over the track length, many different track lengths in the samples A. Calcaterra

  30. Tue 2011/11/22, 6.5 hours of data Horizontal scale ns, 1bin=2ns. We plot Dt if majority=2, or the biggest time difference out of 3 (majority=3) or out of 6 (majority=4) A. Calcaterra

  31. Next steps (very soon) • Use BESIII signals into our own DAQ instead of auto-generated one but read data onto our separate PC. • Implement the TDC (100 ps resolution) • Estimate data size in real running conditions • Expected size = 1 byte per channel per BESIII trigger per window size (1 sample/2 ns) • 200 ns window  16 bytes*100 samples A. Calcaterra

  32. Next steps (not much later) • After data size is known (and accepted )… • …and we demonstrate that the data may be useful… • …then, we will finally ask to incorporate VME readout into BESIII general dataflow • At this point, help will be needed from expert BESIII DAQ- and offline-reconstruction persons A. Calcaterra

  33. Conclusions • The ZDD has been designed, built, and tested in record-time • The design is sound and the performances are acceptable given the relatively little time and effort left for data taking and analysis • The installation was hard but the final result is satisfactory • Next stop…….physics results A. Calcaterra

  34. A final thought of wisdom “One knows very well that, in reducing ideals to practice, great latitude of tolerance is needful; very great” T. Carlyle A. Calcaterra

  35. Spares A. Calcaterra

  36. The HV correction • Let’s choose a “target” amplification (45 pC) • In column 5 we find the factor to correct for • According to • We compute A. Calcaterra

  37. PM HV calibration • Initial 8-channel equalization done on the basis of Hamamatsu individual datasheets • For all events, find pedestals and peaks • Choose one channel as normalization • Assuming (Hamamatsu datasheets) • Invert formula and find new Vn’s A. Calcaterra

  38. FADC scale calibration A. Calcaterra

  39. Run 228, cosmics, QDC data A. Calcaterra

  40. Run 228, cosmics, FADC data Peak in channels 1,2,3 is a factor 2 higher than in channel 0, just as expected. This is a good thing! A. Calcaterra

  41. Conversion factors at 1.4 kV • Run 228: no “Happy Box”: 5.5 pC/MeV of scintillator-deposited energy • QDC+FADC cosmics data: unfortunately, a small sample (1 day only) A. Calcaterra

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