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MiniBooNE Update: cross sections & oscillations

MiniBooNE Update: cross sections & oscillations. Paul Nienaber Saint Mary’s University of Minnesota for the MiniBooNE Collaboration July 28 2009 -- DPF2009. MiniBooNE’s original raison d'être. motivated by LSND observation of electron antineutrino events in a muon antineutrino beam.

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MiniBooNE Update: cross sections & oscillations

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  1. MiniBooNE Update:cross sections&oscillations Paul Nienaber Saint Mary’s University of Minnesota for the MiniBooNE Collaboration July 28 2009 -- DPF2009

  2. MiniBooNE’s original raison d'être • motivated by LSND observation of electron antineutrino events in a muon antineutrino beam PRD 64, 112007 (2001) MiniBooNE Update -- DPF2009

  3. MiniBooNE’s original raison d'être • motivated by LSND observation of electron antineutrino events in a muon antineutrino beam • MB start: muon neutrino beam • different L, E; same L/E MiniBooNE Update -- DPF2009

  4. MiniBooNE’s original raison d'être • motivated by LSND observation of electron antineutrino events in a muon antineutrino beam • MB start: muon neutrino beam • different L, E; same L/E • 6.9 E+20 POT neutrino mode • 5.1 E+20 POT antineutrino mode about 2 mg of protons delivered to date! MiniBooNE Update -- DPF2009

  5. MiniBooNE’s original raison d'être • motivated by LSND observation of electron antineutrino events in a muon antineutrino beam • MB start: muon neutrino beam • different L, E; same L/E • 6.9 E+20 POT neutrino mode • 5.1 E+20 POT antineutrino mode pion production (& hence  flux) well constrained by HARP data/analysis Eur. Phys. J. C52, 29 (2007) MiniBooNE Update -- DPF2009

  6. Collaborators from Alabama, Bucknell, Cincinnati, Colorado, Columbia, Embry- Riddle, Fermilab, Florida, Illinois, Indiana, Los Alamos, LSU, MIT, Michigan, Princeton, Saint Mary’s, Virginia Tech, Yale MiniBooNE Update -- DPF2009

  7. overview • cross section measurements • oscillation analyses MiniBooNE Update -- DPF2009

  8. cross section measurements neutrino CC cross sections when dinosaurs roamed the Earth (i.e., pre- MiniBooNE) MiniBooNE Update -- DPF2009

  9. cross section measurements these numbers are of fundamental interest, but also relevant to future experiments MiniBooNE Update -- DPF2009

  10. cross section measurements these numbers are of fundamental interest, but also relevant to future experiments NOvA CNGS T2K MiniBooNE Update -- DPF2009 DUSEL

  11. cross section measurements these numbers are of fundamental interest, but also relevant to future experiments focus here on two processes: CC QE (signal for oscillation) MiniBooNE Update -- DPF2009

  12. cross section measurements these numbers are of fundamental interest, but also relevant to future experiments focus here on two processes: CC QE (signal for oscillation) NC π0 (background) MiniBooNE Update -- DPF2009

  13.  W+ n cross sections: CCQE LARGE SAMPLE! 146,070  QE events (76% purity, 27% ) [analyzed, after cuts] provide most complete information on  QE scattering to date (full  kinematics: E and ) MiniBooNE Update -- DPF2009

  14.  W+ n cos T (GeV) cross sections: CCQE (T. Katori) (draft in preparation) MiniBooNE Update -- DPF2009

  15.  W+ n cos T (GeV) cross sections: CCQE (T. Katori) first double differential cross section for  QE!! (draft in preparation) MiniBooNE Update -- DPF2009

  16.  W+ n cross sections: CCQE • - Q2shape fit results: MA=1.35  0.17 GeV- Higher value of MA also consistent with total vs. E • - Consistent w/ K2K, MINOS, but not w/ MAD2 =1.03 GeV MiniBooNE Update -- DPF2009

  17.  W+ n preliminary cross sections: CCQE • - Q2shape fit results: MA=1.35  0.17 GeV- Higher value of MA also consistent with total vs. E • - Consistent w/ K2K, MINOS, but not w/ MAD2 =1.03 GeV model predictions, NOT fits RFG = relativistic Fermi gas (v. Smith & Moniz, NP B43, 605 [1972]) MiniBooNE Update -- DPF2009

  18.  W+ n preliminary cross sections: CCQE • MiniBooNE and recent SciBooNEin good agreement • Both higher than recent NOMAD QE ?! (all three on 12C) look to MINOS and MINERA for more data MINOS, MINERA MiniBooNE Update -- DPF2009

  19. 0 n,p n,p cross sections: NC 0 LARGE SAMPLE! neutrino: 21,542 NC 0 events (73% purity, 36% ) antineutrino: 2,305 NC 0 events (58% purity, 36% ) 0 MiniBooNE Update -- DPF2009

  20.  0 cos p(GeV)   n,p n,p cos p(GeV) cross sections: NC 0 (C. Anderson) (draft in preparation) [flux averaged] MiniBooNE Update -- DPF2009

  21.  0 cos p(GeV)   n,p n,p cos p(GeV) cross sections: NC 0 (C. Anderson) (draft in preparation) first measurement of absolute NC 0 differential cross section [flux averaged] MiniBooNE Update -- DPF2009

  22. cross sections: summary M O R E ! ! ! -- CC +/CCQE: arXiv:0904.3959 [hep-ex] [S Linden, J Nowak] -- CC +: d/dT, d/dd2/dTd , d/dT, d/d, d2/dTd,d/dQ2, (E) [M Wilking] --  NC elastic: d/dQ2[D Perevalov] MiniBooNE Update -- DPF2009

  23. oscillations I: e appearance • 2007 result: • In analysis region • 475 < E < 3000 MeV, • no evidence for oscillation • (interpretation of LSND as simple • two-neutrino oscillation excluded at 98% CL) • Unexpected excess of events at low energy < 475 MeV 5.6  1020 POT PRL 98, 231801 (2007) MiniBooNE Update -- DPF2009

  24. oscillations I: e appearance • 2009 update: • improved statistics, better modelling of some background processes, and enhanced cuts on external interactions • analysis threshold extended down to 200 MeV • over 475 MeV: • no change MiniBooNE Update -- DPF2009

  25. oscillations I: e appearance • 2009 update: • improved statistics, better modelling of some background processes, and enhanced cuts on external interactions • analysis threshold extended down to 200 MeV • under 475 MeV: • excess persists PRL 102, 101802 (2009) MiniBooNE Update -- DPF2009

  26. __ oscillations II: eappearance • -- statistics are low (does not include spring 2009 runs) • -- no definitive statement on LSND yet • -- no low energy excess?! (G. Karagiorgi) - arXiv:0904:1958 [hep-ex] - arXiv:0904.1958 [hep-ex] submitted to PRL MiniBooNE Update -- DPF2009

  27. oscillations III: disappearance • at 90%CL, no neutrino or antineutrino disappearance observed • neutrino results agree with earlier experiments (CDHS + CCFR) • antineutrino results map out new excluded region in parameter space  mode  mode (K. Mahn) MiniBooNE Update -- DPF2009 arXiv:0903.2465 [hep-ex] (PRL in proof)

  28. conclusions • cross section results: • unprecedentedly large samples allow measurements to be unpacked as differential rather than total • flux understanding (HARP, &c.) allows absolute rather than ratio measurements • some interesting unanswered questions (MA, &c.) • oscillations: • provenance of low energy excess remains an open question • antineutrino results await more statistics MiniBooNE Update -- DPF2009

  29. coming attractions… • combined antineutrino/neutrino appearance analysis • combined MiniBooNE/SciBooNE disappearance analysis • three more years antineutrino running MiniBooNE Update -- DPF2009

  30. coming attractions… • combined antineutrino/neutrino appearance analysis • combined MiniBooNE/SciBooNE disappearance analysis • three more years antineutrino running • MicroBooNE: liquid argon TPC in BNB line, upstream of MiniBooNE • upgrade to BooNE: second detector see B Fleming Friday morning plenary! MiniBooNE Update -- DPF2009

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