HARP Results: Neutrino Physics, Hadron Production Models, and Prospective Conclusions

1. Production Studies:the HARP resultsWP2 December 2008 EURO ν Maria Gabriella Catanesi INFN Bari Italy

2. Outline • Why HARP ? • The detector • HARP results: • K2K & MiniBoone fluxes • Super Beams & Neutrino Factory Design • Atmospheric fluxes ( < 15 GeV) • Hadron Production Models • Prospective & conclusions

3. Harp • Inaugurates a new era in Hadron Production for Neutrino Physics: • Based on a design born for Heavy Ions physics studies • Full acceptance with P.Id. • High event rate capability (3KHz on TPC) • Built on purpose • Collaboration includes members of Neutrino Oscillation & Cosmic rays experiments (124 Physicists from 20 institutions) • And makes measurements on specific targets of existing neutrino beams.

4. 10 Daughter energy 1 TeV 100 10 1 GeV 1 GeV 10 100 1 TeV 10 Parent energy Existing measurements at the end of the millennium Boxes show importance of phase space region for contained atmospheric neutrino events. Barton et. al. • Overall quoted errors • Absolute rates: ~15% • Ratios: ~5% • These figures are typical of this kind of detector setup Abbott et. al. Measurements. 1-2 pT points 3-5 pT points >5 pT points Eichten et. al.

5. HARP: Data taking summary HARP took data at the CERN PS T9 beam line in 2001-2002 Total: 420 M events, ~300 settings SOLID: n EXP CRYOGENIC:

6. Forward Spectrometer: • 30 mrad <  < 210 mrad. • 750 MeV/c < p < 6.5 GeV/c • K2K,MiniBoone, Cosmic rays Detector layout Forward spectrometer Large Angle spectrometer • Large Angle Spectrometer: • 0.35 rad <  < 2.15 rad • 100 MeV/c < p < 700 MeV/c • Super Beams - Nufactories More details in the NIM paper “The Harp Detector @ the CERN PS”

7. FORWARD ANALYSIS

8. theta-p plane: elastics 0.2 TOF 0.1 empty target beam 0. 8 3 5 1.5 0.5 ELASTICS FW: Momentum Resolution TOF BEAM open: data filled: MC

9. CAL TOF CERENKOV CERENKOV TOF FW: PID principle

10. 2.0 1.5 2.5 0 0.5 1.0 Relevance of HARP for K2K neutrino beam One of the largest K2K systematic errors comes from the uncertainty of the far/near ratio pions producing neutrinos in the oscillation peak measured by HARP oscillation peak K2K far/near ratio En(GeV) K2K interest Beam MC confirmed by Pion Monitor Beam MC

11. Far/Near Ratio in K2K Predicted Flux Shape Predicted Far/Near Ratio Near Detector HARP gives ~ factor 2 error reduction across all energies Far Detector Nucl.Phys.B732:1-45,2006 hep-ex/0510039

12. π+ MiniBoone : Harp Be 8.9 GeV 5% λ Harp Forward Spectrometer Acceptance (But also SCIBOONE)

13. HARP Be 8.9 GeV/c data Sanford-Wang parametrization

14. main source of νe flux for MiniBooNE K± production data thick targets π- production data More HARP data for accurate flux predictions coming: Direct measurement with rescattering and absorption Anti-neutrino flux measurement p K p

15. - data needed for MiniBooNE antineutrino flux Paper in preparation

16. primary flux decay chains Atmospheric neutrino fluxes • Primary flux is now considered to be known to better than 10% • Most of the uncertainty comes from the lack of data to construct and calibrate a reliable hadron interaction model. • Model-dependent extrapolations from the limited set of data leads to about 30% uncertainty in atmospheric fluxes •  cryogenic targets N2,O2 hadron production

17. Model comparison: p+C→++X

18. Results for p+O2 or p+N2 cryo targets

19. More targets, more momenta Available: Be, C, Al, Cu, Sn, Ta, Pb at 3, 5, 8, 12 GeV/c Can be used for complete parametrizations or tuning of models Low energy data useful for cascade calculations These data were taken with lower statistics than the dedicated runs for K2K and MiniBooNE Some example spectra:

20. HARP pBe @ 3, 5, 8, 12 GeV/c

21. HARP pAl @ 3, 5, 8, 12 GeV/c

22. HARP pPb @ 3,5, 8, 12 GeV/c

23. HARP pA A-dependence

24. HARP p-A trends with A

25. Comparisons with models Some examples

26. pAl @ 12.9 GeV/c versus GEANT4

27. Model comparison: p+C→+X

29. π± Ta -> π± X 3 GeV/c

30. π± Ta -> π± X 5 GeV/c

31. π± Be -> π± X 5 GeV/c

32. Large Angle Analysis

33. LA Spectrometer performance p-p PID with dE/dx momentum calibration: cosmic rays elastic scattering momentum resolution PID: dE/dx used for analysis TOF used to determine efficiency p-e PID with dE/dx elastic scattering: absolute calibration ofefficiency momentum angle (two spectrometers!)

34. The elastic scattering benchmark momentum scale [1/p (predicted-measured)]/(1/p) Comparison of predicted vs measured track allows LA tracking benchmark missing mass peak from large angle proton track (position of peak verifies momentum scale -- +15% shift is completely excluded) efficiency Momentum scale Sys. Error < 3%

35. Stability from LH2 target to other targets consider average momentum of protons with dE/dx [7-8] MIPs H2 setting H2 Al 13 12 8 5 3 Carbon 12 8 5 3 Tin 12 8 5 3 2% Copper 12 8 5 3 Lead 12 8 5 3 Be 12 9 8 5 3 Ta 12 8 5 3

36. Example of future projects • Primary energy, target material and geometry, collection scheme • maximizing the π+, π-production rate /proton /GeV • knowing with high precision (<5%) the PTdistribution • A possible scenario: from 2.2 GeV/c to 8 GeV/cproton linac. • Phase rotation • longitudinally freeze the beam: slow down earlier particles, accelerate later ones • need good knowledge also of PL distribution

37. + Neutrinofactorystudy - Ta Target Data + - yield/Ekin ds/dq cross-sections can be fed into neutrino factory studiesto find optimum design The optimal energy is between 5 and 8 GeV/c published on EPJC

38. Low θ tracks in the TPC: (250 – 350 mrad) We can measure these tracks but: Worse resolution & lower efficiency

39. Neutrino factorystudy (cont’) it’s also possible to enlarge the phase space (if we accept larger errors) On going analysis

40. π-π+ ratios for light and heavy nuclei

41. Pionyields comparison of p+ and p- and yields for p-A for Be, C, Cu, Sn, Ta and Pb forward production only 0.35 < q < 0.95 rad p+ p-

42. Pionyields A-dependence of p+ and p- and yields for p-A for Be, C, Cu, Sn, Ta and Pb (3, 5, 8, 12 GeV/c) forward production only 0.35 < q < 1.55 rad p+ p-

43. proton beams on long targets Data analysed on tantalum and carbon targets (lead later) Especially useful for the neutrino factory target Interesting to tune models for re-interactions (and shower calculations in calorimeters etc.) As for the thin targets, corrections for the absorption and re-interaction of the produced particles are made NO correction is made for the absorption and re-interaction of the beam proton (this is what we want to measure) Data are not directly applicable: our targets are 30mm in diameter: more re-interactions of the scattered proton

44. LONG C TARGET p-C p- PRELIMINARY forward 0.35 < q < 1.55 backward 1.55 < q < 2.15

45. FW and BW p-C p+ 100% vs 5% TARGET 100% l target 5% l target PRELIMINARY

46. bin-by-bin ratio 5 GeV/c beam: p-C p+/- 100% / 5% TARGET Large corrections ! If no effect from absorption of p: expect ratio = 1 If all interacting p are lost: expect ratio = 0.65 p- p+ PRELIMINARY

47. bin-by-bin ratio 12 GeV/c beam: p-C p+/- 100% / 5% TARGET If no effect from absorption of p: expect ratio = 1 If all interacting p are lost: expect ratio = 0.65 p+ p-

48. bin-by-bin ratio 5 GeV/c beam: p-Tap+/- 100% / 5% TARGET If no effect from absorption of p: expect ratio = 1 If all interacting p are lost: expect ratio = 0.65 p+ p-

49. bin-by-bin ratio 12 GeV/c beam: p-Tap+/- 100% / 5% TARGET If no effect from absorption of p: expect ratio = 1 If all interacting p are lost: expect ratio = 0.65 p- p+

50. HARP publications Forward analysis Measurement of the production cross-section of positive pions in p-Al collisions at 12.9 GeV/c (K2K target measurement) M.G. Catanesi et al, hep-ex/0510039,Nucl. Phys. B732: 1-45 (2006) Measurement of the production cross-section of positive pions in the collision of 8.9 GeV/c protons on beryllium (MiniBooNE target measurement) M.G. Catanesi et al,Eur.Phys.J.C52:29-53,2007. Measurement of the production cross-section of pi+ in p-C and pi- C Interactions at 12 GeV/c M.G.Catanesi et al : Astroparticle Physics - volume/issue: 29/4 pp. 257-281 Forward production of pi+/pi- in p-O2 and pN2 interactions at 12 GeV/C M.G.Catanesi et al :Astroparticle Physics - volume/issue: 30/4 pp. 120-150 Forward production of charged pions in the HARP experiment with incident pi+/pi- on nuclear targets M.G.Catanesi et al : Accepted by Nuclear physics A In preparation : Full characterization of the MiniBoone/SciBoone  neutrino beam(pi-, kaon, protons, thick and replica target)Forward production of charged pions with incident protonson different nuclear targetsForward production of charged pions with incident protons and pionson different nuclear thick targets