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A New Way to Measure Noise Occupancy in Colliding Beam Data

A New Way to Measure Noise Occupancy in Colliding Beam Data. Steve McMahon RAL. A New Way to Measure Noise Occupancy in Colliding Beam Data. Motivated by the talks of Dan and Naoki Search for a way that avoids the subtraction techniques

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A New Way to Measure Noise Occupancy in Colliding Beam Data

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  1. A New Way to Measure Noise Occupancy in Colliding Beam Data Steve McMahon RAL

  2. A New Way to Measure Noise Occupancy in Colliding Beam Data • Motivated by the talks of Dan and Naoki • Search for a way that avoids the subtraction techniques • Would like to exploit, if possible, the very high intrinsic efficiency of the module • Would like to avoid sensitivities to space point finding and delta rays.

  3. Consider one side of a module made of two strips (1-Pf) Pf For our simple 2 strip module: Pf(1-Pf) (1-Pf)2 Strip 1 Now generalize to one side of a module of 6 x 128 strips: Pf(1-Pf) (Pf)2 Strip 2 1 This number is around 1.1% for a NO of 1.5x10-5 Clearly this assumed all of the strips are uncorrelated

  4. Consider two sides of a single module (1-Pm) Pm We now consider a Ratio of probabilities Pm(1-Pm) (1-Pm)2 Link -0 Pm(1-Pm) (Pm)2 Link-1 We now collect together and substitute from previous page Note that we are not using the red area at all We are assuming that this area ((Pm)2) is dominated by tracks

  5. Some Comments on the study • Based on the TrkValidation n-tuple • Restricted to the Barrel for the moment • Restricted to one time bin (timeBin==2) for the moment • The advantage of this single bin over choosing a single other is Statistics • In some sense this is the toughest test as it is the bin most likely to be contaminated by tracks. • 3 Samples • Cosmic ray data: 148072 • Stand-By data: 142194 • Colliding beam data: 194193 (LBs 29-155) 5319 events

  6. Cosmic Ray Data 142194, 1157 events Noise occupancy in cosmic rays is 1.2x 10-5 Number of modules with at least one hit. one entry per event, mean = 19.4

  7. Colliding beam Data 194193 (LBs 29-155) 5319 events Number of modules with at least one hit. one entry per event, mean = 46 Noise occupancy in pp data is 2.1x 10-5 Tails are gone

  8. Stand-By 20 Volts, run 142194, 6611 events Number of modules with at least one hit. one entry per event, mean = 358 Noise occupancy at 20V is 2x 10-4

  9. Conclusion & Outlook • A new way to define Noise Occupancy has been presented and first results look sensible • It is easy to calculate • Utilizes the very high single module efficiency • Does not rely on subtraction of two "large" numbers to find small numbers • Does not rely on space point finding • Can be done at the single time bin level • The technique does have some weak point but these are mostly weak point with other analyses as well • Not Yet done • Any special subtraction of problematic modules (noisy strips, non functioning chips etc) • Understand the errors • Further Studies • Identify an event level NO measure • Stability as a function of lumi block • Correlations with on-line Calibration results • module level differences between Beam and cosmic • Module level Maps of differences • Values as a function of the chosen time bin • Temperature dependence (Barrels (inner and outer) and End-Caps) • Voltage dependence (intermediate values taken as part of Lorentz angle studies)

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