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HCAL Noise Identification and Filtering (HPD behavior and noise identification)

HCAL Noise Identification and Filtering (HPD behavior and noise identification). Shuichi Kunori 10-Dec-2008 - draft -. Sources of fake MET/HMT and jets.

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HCAL Noise Identification and Filtering (HPD behavior and noise identification)

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  1. HCAL Noise Identification and Filtering(HPD behavior and noise identification) Shuichi Kunori 10-Dec-2008 - draft - HCAL Noise Identification and Monitoring

  2. Sources of fake MET/HMT and jets We designed and built a very hermetic calorimeter for good measurement of large MET. The MET distribution should behave nicely, but… Several sources are known to create “tail” in the MET distribution (and jets). We identify such events and filter them out during event reconstruction and physics analysis. • Calorimeter resolution  MET resolution • Clustered energy • Leading jet(s) have the most impact. • Un-clustered energy • Detector effect • ECAL/HCAL • Hot/dead channels • ECAL APD Nuclear counter effect • HB/HE HPD/RBX noise  CRAFT • Showers in fibers in 53 degree gap • HF PMT/fiber events (behind the HF absorber) • Gap/thin part • eta=0.0 – air gap (covered by HOR0) • eta=1.5 – thin/dead material (complex material distribution) • Eta=3.0 – Endcap edge effect, ES support • Other non-collision events • Cosmic muons (showers)  CRAFT • Beam halo HCAL Noise Identification and Monitoring

  3. HPD Noise Rate in the first CRAFT run R66594 Edward Laird HCAL Noise Identification and Monitoring

  4. 40MHz (pedestal not subtracted) 109 pedestal 40Hz Ion feedback discharge 0.4Hz 0 2 12 40 GeV HPD Noise Spectrum CRAFT Mehmet Deliomeroglu HCAL noise: Coincidence with physics signal is very small, but large noise will appear in the tail of the MET distribution once they are picked up by jet/met trigger. HCAL Noise Identification and Monitoring

  5. Discharge (>60 fC) CRUZET: Alfredo Gurrola / Latife Nukhet Vergili / Ming Yan HCAL Noise Identification and Monitoring

  6. CRUZET3 Low energy coherent noise - Need a jet trigger HCAL Noise Identification and Monitoring

  7. HCAL Noise in CRAFT HPD # of hits Red: RBX noise – Noise in multiple HPD’s Blue: HPD noise (ion feedback etc.) – HPD hits < 9 Magenta: HPD Noise (discharge) – HPD hits >= 9 Jet trigger HCAL Trigger Energy in RBX Energy in RBX Ion feedback: 5- 60 GeV RBX noise: 60-380 GeV Discharge: >380GeV Taylan Yetkin / sk HCAL Noise Identification and Monitoring

  8. Two Levels of Filter • HCAL Noise filter – at RecHit creation stage • RBX-by-RBX • Using timing and pulse shape (+ hit multiplicity) • Out-of-time pile-up will be issue. • Implicitly using pattern of hits in phi slice(s) • Good synchronization required. • Monitor latency jump and phase shift. • Align BX during RecHit creation. • JetsMET Noise filter – at Physics analysis stage • Topology in eta-phi-depth space • EM fraction • Jet shape • … • Correlation with ECAL, Tracker and MUON detectors • Timing • Existence of tracks HCAL Noise Identification and Monitoring

  9. # of hits in RBX (E>1.5GeV) 72 18 9 hits TB2007 HE 30GeV pi- 4(h) x 2(f) x 2 (d) TB2007 HE 300GeV pi- 4(h) x 2(f) x 2(d) HCAL Noise Filter Step-1: Timing distribution cut Red: RBX noise Blue: HPD ion feedback (n<9) Magenta: HPD discharge (n>8) 20ns RMS of RecHit time in RBX (E>1.5GeV) - multi hit events - Suvadeep Bose sk ns HCAL Noise Identification and Monitoring

  10. Pulse Shape (TB2006) Cut on Pulse Shape Some noise: - wider or - irregular pattern in 10 time slieces 3ts 10ts Ratio: E(3ts) / E(10ts) 8 # of ADC count 0’s in RBX 0.25 E3/E10 Introduced by Edward Laid 17-july-2008 HCAL Noise Identification and Monitoring

  11. MET Rates Jet Trigger blue – no cut red – after cuts on time spread and pulse shape 0.3 Hz at Met 100GeV after the filter. Muon Triiger 0.01 Hz at MET 100GeV Rate for 8E29 0.2 Hz @ 10E33 Gheorghe Lungu HCAL Noise Identification and Monitoring

  12. Development of Monitoring Tool Use CRAFT data to develop a tool to monitor HCAL noise/Anomalous events in MET events. Runs with > 5M events Oct.18 Nov.08 3 weeks Latife Nukhet Vergili / Taylan Yetkin HCAL Noise Identification and Monitoring

  13. Conclusion • We have good CRAFT data to study fake jets/MET due to HCAL noise and cosmic muons. We use those to develop HCAL noise filter algorithm and monitoring tool. • We plan to create two levels of filters. • Level 1 - HCAL noise filter during RecHit creation • Level 2 - Fake JetMET filter during physics analysis Development of algorithm has started. • Significant Monte Carlo study is required to optimize the filter algorithm for the maximum rejection of fake and the least bias to physics signal. • We have been watching for anomalous events during testbeam, CRUZET and CRAFT. We continue doing so and develop a monitoring tool for physics run/physics analysis. HCAL Noise Identification and Monitoring

  14. Additional slides HCAL Noise Identification and Monitoring

  15. Additional cuts Edward Laid 17-july-2008 nominal pulse shape Charge in late 3ts Charge in 10 ts Calo MET HCAL Noise Identification and Monitoring

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