Background simulation for 35-ton data

1. Background simulation for 35-ton data DUNE 35-ton simulation and reconstruction David Adams BNL October 5, 2016

2. Introduction Like to have realistic BG simulation for 35-ton • Want to understand the effect of BG on signal reconstruction • Can measure this directly if we know the true signal • Need accurate description of the background • Level • Time correlations (frequency spectrum) • Channel correlations • Run-to-run and event-to-event variations in all the above • Effect of BG removal on signal reconstruction • Expect channel-coherent noise removal to have a big effect on the signal • Can be studied without BG but BG will change the removal estimate Redmine ticket created asking for this BG simulation • https://cdcvs.fnal.gov/redmine/issues/14082 • Thanks to Matt for putting this in • And to him and Dom (and me) for contributing to discussion thus far • More ideas and design/code welcome D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

3. Ideas Correlations • There are two types of BG correlations • Coherence: correlation between time bins • Leads to frequency spectrum that is not flat • Correlation: channel-to-channel correlations • Add systematic biases in charge measurements between channels (bad) • BG in one channel can be estimated (and then removed) using the signals from other channels (good) • Signal pollution • I will try to stick with this naming convention (coherence vs. correlation) Two approaches being considered • Direct simulation of the noise • Take noise from the data Following slides consider each separately • Do we want one or both? • Discussion encouraged D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

4. Example noise plots First some example noise frequency plots • From my talk last week • For one “typical” collection and induction channel for one event • I only looked carefully at about 50 channels in the one event • Clearly need a more comprehensive survey before drawing too many conclusions • Observe that correlated noise removal decreases BG by about 50X • But coherent BG is still about 50X above incoherent •  Both coherence and correlation are very important D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

5. Collection example Even with NR, coherent BG dominates. Incoherent BG: 200 (ADC count)2 corresponds to 4.5 (ADC count)/tick D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

6. Induction example Same comments as for collection. D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

7. Direct noise simulation Progressively sophisticated simulation of noise • Get the right level (RMS) using incoherent and uncorrelated noise • Request from Mark last week • Add (time) coherence • I.e. get approximately correct frequency spectrum • Is existing ExponentialChannelNoiseService sufficient? • Do we need more than nearest-neighbor correlations (red/pink noise)? • Add channel correlations • Need these because they are used in noise removal which is likely distorting signals • Requires new service and likely change/addition of interface D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

8. Data-driven noise estimates Take noise from data • I.e. overlay raw data from 35-ton on simulated signal • BG includes both electronic noise and cosmic signals (good?) • So typical signal would be a single muon (or other particle) Want background to be unbiased (or minimally biased) • Scintillator triggers occur in ticks 4000-5000 or 5000-6000 • Depending on run • Do we have any events with unbiased trigger? • E.g. random or accidental • Can we use channels 7000-15000 in scintillator-triggered events? • MC data would have smaller window (8k vs. 15k ticks) that data • OK for most/all studies? • Alternative is to look for events with tick ranges that show no evidence of signal • Then BG would not include cosmics—use this with full cosmic simulation • E.g. if someone wants to use 35-ton to measure cosmic flux D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016

9. The end D. Adams, BNL DUNE FD sim/reco BG simulation October 5, 2016