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University of Iowa

University of Iowa. HF sourcing – Histograming mode Alexi Mestvirishvili. ECLIPSE 06 Antalya, Turkey. HF minus. Main calibration HTR running in histograming mode, QIEs running in normal scale. Reading out of one spigot at the time (24 channels, 12EM, 12HAD)

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University of Iowa

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  1. University of Iowa HF sourcing – Histograming mode Alexi Mestvirishvili ECLIPSE 06 Antalya, Turkey Slide N

  2. HF minus Main calibration HTR running in histograming mode, QIEs running in normal scale. Reading out of one spigot at the time (24 channels, 12EM, 12HAD) During sourcing source was stopped in three different location First and last – for safety reasons. Second stop for 3 minutes – to accumulate data. Position of second stop point was chosen in the way to have both long and short fibers illuminated. Expected signal – 0.01 Signal+Pedeatal x10 QIE counts vs position Ten 10o sectors – 28 – 36 and 1 analyzed so far Slide N

  3. Signal + pedestal and pedestal separation and signal versus tower Gaussian fit applied EM fibers HA fibers Small peak – pure pedestal High peak – Signal+pedestal  For these distributions are 0.0018. 5 wedges 24 tower each Slide N

  4. Problems Run 1566 & 1567 Tower 12, phi 36 Run 1490 Tower 23, phi 33 EM channels HAD channels Gaussian fit sigma for S+P vs Tower Slide N

  5. Problems (run 1566) Red signal + pedestal Green pedestal Four different capacitors Slide N

  6. Calibration Precision • Calibration precision is limited by several factor • Statistical precision of signal • (relative error on signal) • 2. Pedestal stability • 3. Internal nonlinearities of absorber and fibers • (believed to be at the level 5%, not studied for this presentation) • 4. etc. Slide N

  7. Statistical PrecisionPhi=29, tower=16, QIE ch 2,8 • Signal + pedestal • Nentries = 14290 • Mean = 5.05 • Sigma = 0.0018 • Err on Mean • /sqrt(Nentries) =1.5x10-5 • b) Pedestal • Nentries = 3408 • Mean = 5.039 • Sigma = 0.0018 • Err on mean = 3x10-5 a) b) = 5.05 – 5.039 = 0.011  = 3.3x10-5 X axis units – linearized QIE counts /=0.3% Slide N

  8. Relative error on signal Small towers has smaller signals hence big error Slide N

  9. Pedestal stability Pedestal stability can be studied from same data. In one 10o 24 channels (12EM, 12HAD) are read out during sourcing of one tube. Either 16 or 15 tubes are in one phi sector. In each run only two channels (1EM, 1HAD) caries signal. All other channels gives pure pedestal, provided adjacent towers of one which is sourced are excluded from data samples One can easily select samples for the same channel and well separated in time. App 5 minute is necessary to source one tube. For example, two samples for tower 5, when source is in tube 1 (tower 1) and in tube 16 (tower 12) are separated by more than one 1 hour. Slide N

  10. Measure of pedestal stability is width of pedestal distribution ij, ik – tower for which pedestal is determined – towers which are sourced, they are separated in time as far as possible Pedestal stability Condition which has to be fulfilled to avoid contribution From energy leakage from tower to tower Slide N

  11.  of pedestal distributionstower 1 to 12 Smallest tower Is noisy as well Tow 12,=36 Slide N

  12.  of pedestal distributiontowers 13 to 24 Small tower noisy as well Tow 12,=36 Slide N

  13. Geometrical corrections Geometrical corrections has to be applied to signals from each tower to exclude the differences in tower shape. Coefficients were taken from Monte Carlo. They are calculated with respect to the response of infinite size tower taken into account actual tower geometry Coefficients are available in HF monitoring database and they were calculated in CMS IN 2004/002 Slide N

  14. Geometrical correction how they work (problems ?) for EM towers Uncorrected, pedestal subtracted signal for phi = 28 For towers having two source tubes geometrical correction should bring two points close to each other for HAD towers Gains in each group are more or less equal High Medium Low PMT gains Slide N

  15. Geometrical corrections how they work (problems) Same as on previous slide pedestal subtracted, Corrected, signal for phi = 28 Points in red ovals move in opposite direction Points in last group behaves as it should High Medium Low PMT gains Slide N

  16. SUMMARY • In general, data quality is good, signal can be separated • well even for small towers • Statistical precision of HF calibration will be very high, • less than 1%. • 3. Stable pedestal • 4. Some problems were identified – bad capacitors, noisy • channels • 5. Geometrical scale factors has to be recalculated with • correct tower geometry (!!!!!!!!!) Slide N

  17. Backup slides Slide N

  18. – tower for which pedestal is determined – towers which are sourced, they are separated in time as far as possible Stability of pedestal Mean RMS = 0.00046 RMS = 0.00034 RMS = 0.00027 RMS = 0.00034 Slide N

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