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Measuring momentum using TOF0 and TOF1

Measuring momentum using TOF0 and TOF1. Progress report Mark Rayner (Oxford/RAL) Analysis Meeting, 4 th March 2008. Back of an envelope prediction. Expected p resolution performance: Each TOF has a timing resolution of 50ps Time of flight has a resolution ~70ps

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Measuring momentum using TOF0 and TOF1

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  1. Measuring momentum using TOF0 and TOF1 Progress report Mark Rayner (Oxford/RAL) Analysis Meeting, 4th March 2008 Measuring momentum using the TOFs

  2. Back of an envelope prediction • Expected p resolution performance: • Each TOF has a timing resolution of 50ps • Time of flight has a resolution ~70ps • Assume (for now) this is the dominant error • Resolution of 2–3 MeV/c for 200 MeV/c muons • Are there other effects which increase sp? • Look at the beam line from TOF0 to TOF1 • Simple scheme for momentum reconstruction • Try to understand what the important contributions to the error are Measuring momentum using the TOFs

  3. Simple momentum reconstruction • For each individual muon: • Estimate p in the air between TOF0 and TOF1 • Time of flight • Straight line distance TOF0 hit to TOF1 hit • Estimate p before TOF0 • Momentum losses from PDG dE/dx for minimum ionizing particles • Estimate p after TOF1 Measuring momentum using the TOFs

  4. TOF0 and the Cherenkov “Special Virtual Planes Give MC truth at planes (t, x, y, z), (E, px, py, pz) TofHits Give MC truth inside TOFs (t, x, y, z), (E, px, py, pz) TofSpacePoints Give “reconstructed” ADC and TDC hits Only (t, x, y, z) muons Cherenkov TOF0 Emitted light Scattered electrons Measuring momentum using the TOFs Wall

  5. Q7, Q8, Q9 and TOF1 muons • There are more special virtual planes in the region of quadrupoles 7, 8 and 9 • Corrected to be twice as large so as to encompass all the particles Q7 Wall Q8 Q9 TOF1 inside its cage Measuring momentum using the TOFs

  6. Tracker 1 and the first absorber muons • Stage 6 was simulated due to a problem with Stage 2 simulations which Chris has now solved Measuring momentum using the TOFs

  7. Absorbers, focus coils and RF muons • Focussing or just scraping? • Could investigate further with analysis package Measuring momentum using the TOFs

  8. Tracker 2 and the last PID detectors muons • And finally, for completeness… Measuring momentum using the TOFs

  9. Possible factors affecting p resolution • Properties of the TOF0  TOF1 beam line • Width of the Landau distribution of energy loss • Scattering • Focusing in quadrupole magnets • Scraping • Properties of the TOF stations • Timing resolution • Spatial resolution • Dealing with ‘corner clippers’ Measuring momentum using the TOFs

  10. Timing and spatial resolution • Variables • Time of flight, t • space point displacement, s • Both available in my Monte Carlo as • Monte Carlo Truth • Reconstructed values based on detector simulation Measuring momentum using the TOFs

  11. What is ? • Histograms • Shaded  Monte Carlo truth s and t used to construct Pair • Line  reconstructed, simulated ADC and TDC counts used • Mean  energy loss to beginning/end of TOF0–1 channel • RMS  RMS deviation of Pair from true P/Pz before/after TOF0–1 channel Measuring momentum using the TOFs

  12. Simple p reconstruction conclusions • ‘Intrinsic’ momentum resolution is ~2 MeV/c • This is comparable to that resulting from the predicted TOF timing resolution • 70ps  2 – 3 MeV/c • Average x’ is <1 degree • pz is equivalent to p at this precision • sp just before TOF0 • 2.8 MeV/c intrinsically • 5.2 MeV/c including measurement errors • sp just after TOF1 • ~3.7 MeV/c intrinsically • ~5.9 MeV/c including measurement errors • Measurement errors contribute less than 50% of sp • sp/p ~ 3% Measuring momentum using the TOFs

  13. Extra slides Measuring momentum using the TOFs

  14. PDG estimates Measuring momentum using the TOFs

  15. ‘Landau’ distribution of energy loss TOF0 TOF1 Cherenkov • Width of the energy loss distribution • Lowers our momentum resolution up/downstream of the TOFs • 2 – 3 MeV, 1% overall broadening • Histograms of energy loss / MeV Measuring momentum using the TOFs

  16. Scattering TOF1 TOF0 • Causes muons to deviate from a straight line between TOF0 and TOF1 • Increased path length • Underestimate momentum • 1 – 2 degrees overall • Histograms of scattering angle / degrees Cherenkov Measuring momentum using the TOFs

  17. Focusing in quadrupole magnets Q789 • Also causes muons to deviate from a straight line between TOF0 and 1 • ~5 degrees over Q7-9 • More significant than scattering • Histogram / degrees • 3000 incident muons • 1133 transmitted with quads • Only 659 without Measuring momentum using the TOFs

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