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Initial MIPP-Ckov investigations

Initial MIPP-Ckov investigations. Patricia Vahle July 28, 2006. MIPP Ckov. Important apparatus to distinguish pi’s from K’s from protons at 3-17 GeV Important energy range for MINOS. Beam. What does it look like?. How does it work.

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Initial MIPP-Ckov investigations

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  1. Initial MIPP-Ckov investigations Patricia Vahle July 28, 2006

  2. MIPP Ckov • Important apparatus to distinguish pi’s from K’s from protons at 3-17 GeV • Important energy range for MINOS Beam

  3. What does it look like?

  4. How does it work • Particles traveling with velocity greater than speed of light in a medium emit cerenkov radiation • Moreover, the amount of light emitted per unit path length depends on the velocity of the particle (and since we know the momentum, we can get the mass of the particle.)

  5. PID with Ckov MIPP Proposal L. Wiencke’s Thesis π Photoelectrons measured/predicted for β=1 K p

  6. Thresholds From D. Lange’s Feb. 8, 2003 collaboration meeting talk

  7. Status • Code to find tracks in Ckov based on tracks in TDC+Drift chambers is written and working • PMT’s+Mirrors must be intercalibrated • x4 variation in light output among mirrors (?) • PID likelihood needs to be developed

  8. Calibration • My plan of attack: • At high momenta, all particles should produce the same amount of light/distance traveled through cerenkov gas • Make histograms of ADC/pathlength for each mirror for tracks with high momenta • Determine constants to equalize the means of these histograms • Start with empty target, 120 GeV data to avoid complications. . .

  9. Wrinkles in the plan • Light doesn’t only hit one mirror • OK, can correct for this • Still need to select good tracks • Cut on multiplicity • Cut on good fit variable • Cut on track x,y at target positions • Require hits in TDC(?) • Empty target tracks mostly hit the same 1-2 mirrors

  10. ~15 cm (center mirrors) ~6 cm (not to scale) Mirror Light Fract. Correction • Pre-exisiting code calculates fraction of light expected to hit each mirror • Traces photons emitted at 160 positions around the particle trajectory and tabulates which mirror that photon hits • Want to calibrate the quantity: • ADC/(pathlen*lightFract) • for each mirror

  11. Validating Light Frac. Measured ADC vs. expected Light Fraction For 4 central mirrors This makes sense. . . Computed light fraction vs. track position (relative to mirror center) But does this?

  12. Cuts • Require only 1 track in event to point to a given central mirror (to cut out pileup in central mirror) • Require track goodness of fit>0.01 • Require position of particle within a 10 cm radius of 0,0 at the target position • Require hits in the TPC

  13. Effect of Cuts ADC/Light Fract vs. Momentum for mirror 17 (a central mirror) Successive cuts clean up low momenta, high adc region This one shows what it would look like if I just used events with 1 track

  14. A Few plots • ADC/(Pathlength*lightFract) vs momentum for 4 central mirrors • 120 GeV proton “empty target” run • Require adc>3 • Require light fract >0.02 Strange cutoff—related to light fraction?

  15. Y-projections for tracks with p>50 GeV (these are projections, don’t believe the “entries” number)

  16. More ADC plots Same as previous but with Light Fract >0.5 Peaks are wide, and max light is rather low, worrisome?

  17. ADC vs. Run • Calibration histogram of a single mirror moves around within a run, is there any other data to calibrate within a run? • Temperature • Pressure changes • PMT gain ADC/(pathlen*lightFract) for mirror 17 in 9 runs Y Projections of above, each color a different run

  18. Processing issues • Run off Ntuples made in CkovMatchTrk • Must do entire reco chain • Can I write out RBTracks to a file • Still getting many 10’s of “matrix is singular errors” per event • Not quick (7 hrs for 5000 events=5 sec/event) • I’d like to take advantage of a batch system • Can I run at FNAL user batch farms (is the software available at FNAL over afs?)

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