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BBC FEM problem

BBC FEM problem. BBC expert Kotaro M Kijima. online monitor. Sift crew found problem of BBC on online monitor. I checked raw data of BBC. 8 channels are strange behavior. These 8 channels came from same FEM board . North bottom channel 104 ~ 111 (Bad channel). Tdc distribution. ch 0.

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BBC FEM problem

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  1. BBC FEM problem BBC expert Kotaro M Kijima

  2. online monitor • Sift crew found problem of BBC on online monitor. • I checked raw data of BBC. • 8 channels are strange behavior. • These 8 channels came from same FEM board. • North bottom • channel 104 ~ 111 (Bad channel)

  3. Tdc distribution ch 0 ch 0 Tdc0 Tdc1 good channel ch 104 ch 104 Tdc1 Tdc0 bad channel Other bad channels have same peak in Tdc distribution

  4. Adc distribution This distribution already subtracted pedestal. fake pedestal ch 0 ch 0 selection Tdc0 < 2000 good channel to subtract fake pedestal ch 104 ch 104 bad channel ADC distribution seems like fine, but we cannot subtract fake pedestal...

  5. Adc distribution * subtracted pedestal * selection :: Tdc0 < 2000 ch 105 ch 106 bad channel bad channel ch 107 ch 108 bad channel bad channel Fake pedestal

  6. summary • The bad channels come from same FEM board, 8 channels of north bottom. • Tdc distribution of bad channels has strange peak on 0. • Raw Adc distribution of all channels seems like fine. But fake pedestal not be able to subtract for bad channels due to value of Tdc (tdc0,1=0...).

  7. comparison with ch0 and ch104 at internal Q-Scan BBC expert Kotaro M Kijima

  8. comparison with ch0 and ch104 at internal Q-Scan we can see slowing effect for good channels. NOTE:: not same range of x-axis for top and bottom ! ch 0 ch 0 ch 0 Adc [ch] Good Channel Adc [ch] Tdc0 [ch] Tdc0 [ch] ch 104 ch 104 ch 104 Adc [ch] Bad Channel 0 Tdc0 [ch] Adc [ch] Tdc0 [ch] Tdc and Adc distribution are strange for bad channels...

  9. Adc [ch] Adc [ch] 700 700 1000 1000 comparison of Adc distribution between good(Mar2nd) and bad(Mar10th) at Q-Scan red :: good(3/2) blue:: bad(3/10) black line :: fake pedestal light blue :: pedestal We can see that fake pedestal of good and bad locate same value.

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