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TDC test beam data analysis

TDC test beam data analysis. B. Angelucci Università di Pisa & INFN Pisa 01/04/2009. Introduction Hit distribution & noisy channels Missed hits in algo A & B PMT time resolution. ~25 cables. ~400 PMs. TELL1. TDCB. NINO CARDS. TDCB. TDCB. 1 Gb channel. PC & STORAGE. TDCB.

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TDC test beam data analysis

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  1. TDC test beam data analysis B. Angelucci Università di Pisa & INFN Pisa 01/04/2009 • Introduction • Hit distribution & noisy channels • Missed hits in algo A & B • PMT time resolution

  2. ~25 cables ~400 PMs TELL1 TDCB NINO CARDS TDCB TDCB 1 Gb channel PC & STORAGE TDCB GBE Laser Ext trigger Layout of 400PMT RICH Prototype test • Variable frequency (~Hz - ~MHz ) • Only one GBE output channel (max 1GBit/s) • ~2% channels masked • Test with 400 PMs • Laser and defocusing lens, ~30PMT fire each laser pulse

  3. Setup

  4. Noisy channels 10 kHz 100 kHz ch91 ch76 channel channel Evidence of a difference between 10kHz and 100 kHz runs, for some channels (33, 42, 63, 69, 76, 91, 111, 137, 139, 155, 159, 169, 177, 179, 222, 258, 396, 417, 424)

  5. Noisy channels Events all channels channel 91 channel 90 window of absolute time ~20s

  6. Noisy channels 100us Events all channels channel 91 channel 90 Noise independent from events’ rate: more relevant in 10kHz runs

  7. Missed hits in Algo A 10 kHz 100 kHz Number of words per event Number of words per event • It is expected only an even number of words (leading & trailing edge) • From data: uniform distribution (odd/even) in 10kHz runs, even predominance in 100kHz runs

  8. Missed hits in Algo A 100 kHz Difference between number of trailing and leading per event for 100kHz runs • The peak at dTL=0 indicates the predominance of an even number of words • An odd |dTL| means an odd number of words • dTL≠0 shows the presence of unpaired leading or trailing

  9. Missed hits in Algo A 30 leading 26 trailing Algo A scheme 120 clk edges readout window adjustable offset • The leak of trailing words is partially recovered from next event Example of event in which dTL= -4 3 trailing from next event

  10. Missed hits in Algo A • Good events means no unpaired leading or trailing • Not justified means not totally recovered • Under analysis: debugging using pattern generator in progress

  11. Wait trigger on data trigger Readout window data flux in LB Missed hits in Algo B 10 kHz 100 kHz Number of words per event Number of words per event Algo B scheme

  12. Missed hits in Algo B • Good events means no unpaired leading or trailing • Not justified means not totally recovered • Under analysis: debugging using pattern generator in progress

  13. Differences Trailing time – Leading time <tT – tL> for each channel σ[tT – tL] for each channel tL tT The difference tT-tL is rather proportional to signal’s amplitude threshold

  14. Resolution (ref ch14) Offset <∆t(chx-ch14)> for each channel Raw resolution for each channel Offset and raw resolution: analizing the time difference ∆t(chx-ch14) for each event with both chx and ch14

  15. Slewing correction for time resolution mean of each binx content fit function (2nd degree) ∆t(ch31-ch14) vs (tT – tL)ch31 for each event

  16. Raw & corrected resolutions ∆t(ch31-ch14) raw ∆t(ch31-ch14) corrected σraw ~ 540 ps σcorr ~ 200 ps

  17. Conclusions • A detailed analysis of test beam data has been presented • Comparison between 10kHz and 100kHz runs points out the presence of ~5% noisy channels (due to front-end electronics) • Most of the events show no more than one lost hit over ~ 60 at the edges of the readout window. Probable bug in the firmware under investigation • Single photo-electron time resolution of PMTs in fair agreement with measurements with CAEN TDCs (<250ps) • Next step: systematic measurements using fast and high resolution pattern generator

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