1 / 17

Using Muon Removed files to assess the purity of the nubar-PID selection

Using Muon Removed files to assess the purity of the nubar-PID selection. Pedro Ochoa MINOS Collaboration Meeting September 2006. all. Prob( , ndf) > 0.1. NC. / ndf < 20. Introduction.

macy
Download Presentation

Using Muon Removed files to assess the purity of the nubar-PID selection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Using Muon Removed files to assess the purity of the nubar-PID selection Pedro Ochoa MINOS Collaboration Meeting September 2006

  2. all Prob( , ndf) > 0.1 NC / ndf < 20 Introduction • Nubar-PID selection allows to separate antineutrinos with very high purity and reasonable efficiency: + + Basic cuts: fiducial volume track quality fit probability 1m < Zvtx < 5m track fit pass rvtx < 1m UVasym < 6 then apply nubar-PID: For a cut at nubar-PID=1.0, MC shows: L010185 MC Overall purity: 99.75% Overall efficiency: 45.98% • Do we believe this high purity?

  3. m- m+ p p+ K+ • Can separate the background • into two categories: • Category 1: m- is reconstructed as m+ due to hard scattering and/or pattern recognition problems = misidentified • Category 2: tracker fooled by positive particle (decay in flight, proton, pion, kaon… ) = fake Background (124 events total) trkIdHEP=13  Category 1 • Use IdHEP of tracked particle: trkIdHEP!=13  Category 2 About ~1/3 of the background pertains to category 2: 124 background events of nubarPID > 1.0 selection *Note: Category 1 contains a small component of misidentified negative stuff from hadronic shower.

  4. Category 2 example – NC (p decay in flight) tracked particle

  5. Category 2 example – NC (proton)

  6. Category 2 example – n CC (Λc+)

  7. Category 2 example – n CC (K+)

  8. True_y of CC n, category 2 • CC subcategory of Category 2 events seem to be highy Can use MRCC files to answer whether category 2 events are reasonably well modeled. • “Good” MRCC selection: best_purity > 0.8 best_complete > 0.8 best_purity_phw > 0.8 best_complete_phw > 0.8 (see Anna H. talk, minos-doc 2164) Event has to be best match to original data MC scaled to POT data MC scaled to POT Purity= Completeness= Means: Data: 0.975 MC: 0.973 Means: Data: 0.952 MC: 0.958

  9. Run MRCC Data and MC though selection data/MC data MC scaled to # events data/MC data MC scaled to POT

  10. Looking at the signal region: • Scaled to # events: data MC scaled to # events • nubar-PID > 1.0 region: MC: 38.8 ± 10.4 Data: 30 ± 5.5 • nubar-PID > 0.5 region: MC: 88.8 ± 9.4 Data: 96 ± 9.8 • Scaled to POT: data MC scaled to POT • nubar-PID > 1.0 region: MC: 34.2 ± 9.1 Data: 30 ± 5.5 • nubar-PID > 0.5 region: MC: 78.1 ± 8.8 Data: 96 ± 9.8

  11. What about energy dependence? data MC scaled to # events data/MC nubar-PID > 1.0 selection data/MC data MC scaled to # events nubar-PID > 0.5 selection

  12. Summary • Nothing crazy. Lack statistics… • Analysis shows so far that “category 2” background in our nubar-PID > 1.0 selection can be scaled overall by a factor of 0.77 ± 0.25 • Ultimately also need to: • Account for MRCC efficiency and purity • Compare subcategories in MRCC and in MC • What to do if more statistics reveal a considerable energy dependence? One possibility: use ratios in previous slides to scale backgroundbinned in reco energy (removing primary CC n energy if applicable).

  13. BACKUP

  14. NC - Pion decay in flight

  15. CC - Pion

  16. data MC scaled to # events nubar-PID > 0.0 signal: MC: 1895 ± 72 Data: 2123 ± 46 data MC scaled to POT nubar-PID > 0.0 signal: MC: 1666 ± 64 Data: 2123 ± 46

  17. nubarPID>1.0 nubarPID>0.5 nubarPID>0.0

More Related