1. HARP progress SPSC October 2007 Alain Blondel Progress report from HARP Overview of new results Forward analysis Accelerator Neutrino Beam ( K2K, MiniBooNE), Extended Air Showers Large angle analysis Neutrino Factory, A dependence etc.etc. Comments on the RBH report A HAdRon Production experiment at the CERN PS (PS214) Alain Blondel on behalf of the HARP collaboration

2. HARP progress SPSC October 2007 Alain Blondel

3. Università degli Studi e Sezione INFN, Bari, Italy Rutherford Appleton Laboratory, Chilton, Didcot, UK Institut für Physik, Universität Dortmund, Germany Joint Institute for Nuclear Research, JINR Dubna, Russia Università degli Studi e Sezione INFN, Ferrara, Italy CERN, Geneva, Switzerland TU Karlsruhe, Germany Section de Physique, Université de Genève, Switzerland Laboratori Nazionali di Legnaro dell' INFN, Legnaro, Italy Institut de Physique Nucléaire, UCL, Louvain-la-Neuve, Belgium Università degli Studi e Sezione INFN, Milano, Italy P.N. Lebedev Institute of Physics (FIAN), Russian Academy of Sciences, Moscow, Russia Institute for Nuclear Research, Moscow, Russia Università "Federico II" e Sezione INFN, Napoli, Italy Nuclear and Astrophysics Laboratory, University of Oxford, UK Università degli Studi e Sezione INFN, Padova, Italy LPNHE, Université de Paris VI et VII, Paris, France Institute for High Energy Physics, Protvino, Russia Università "La Sapienza" e Sezione INFN Roma I, Roma, Italy Università degli Studi e Sezione INFN Roma III, Roma, Italy Dept. of Physics, University of Sheffield, UK Faculty of Physics, St Kliment Ohridski University, Sofia, Bulgaria Institute for Nuclear Research and Nuclear Energy, Academy of Sciences, Sofia, Bulgaria Università di Trieste e Sezione INFN, Trieste, Italy Univ. de Valencia, Spain The HARP Collaboration 24 institutes ~120 collaborators

4. HARP progress SPSC October 2007 Alain Blondel Hadron production on nuclear targets a) complicated b) uninteresting for hadronic physics c) difficult to measure well ==> data are sparse and Monte-Carlos are very uncertain d) important to optimize Neutrino factory and muon collider design e) absolutely mandatory for neutrino beam experiments f) also LHC simulations and Extended Air Showes measure! Different generators applied to MiniBooNE beam

5. HARP progress SPSC October 2007 Alain Blondel HARP approved 2000 built in 17 months run sept. 2001 -> nov 2002 10 6 triggers at each of these settings Beam line PID Forward detectors (pions, Kaons) --> neutrino beams - K2K, - MiniBooNE, - atmospheric, - Low-medium energy superbeam(s) Large Angle detectors -->neutrino factory Target material Target length (  ) Beam Momentum (GeV) #events (millions) Solid targets Be 2% (2001) 5% 100% ±3 ± 5 ± 8 ± 12 ± 15 For negative polarity, only 2% and 5% 233.16 C Al Cu Sn Ta Pb K2K Al 5, 50, 100, replica +12.9 15.27 MiniBooNE Be+8.9 22.56 Cu “button” Cu+12.9, +15 1.71 Cu “skew” Cu2+12 1.69 Cryogenic targets N7N7 6 cm ±3 ± 5 ± 8 ± 12 ± 15 58.43 0808 D1D1 H1H1 H2H2 18 cm±3, ±8, ±14.5 13.83 Water H20H2010, 100+1.5, +8(10%) 9.6

6. HARP progress SPSC October 2007 Alain Blondel

7. HARP BEAM COUNTERS --identify and count incoming particles (downscaled trigger) --define beam particle impact in target + empty target runs to subtract effect of non-target material and count beam composition in electrons and muons

8. HARP progress SPSC October 2007 Alain Blondel HARP publications - Detectors and performance Laser-Based Calibration for the HARP Time of Flight System M. Bonesini et al, IEEE TRANS. NUCL. SCIENCE, VOL. 50, NO. 4, AUGUST 2003 1053 The time-of-flight TOFW detector of the HARP experiment: construction and performance M. Baldo-Ceolin et al, Nucl. Instr. Meth. A 532 (2004) 548–561 Physics Performance of the Barrel RPC System of the HARP Experiment Bogomilov et al. IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 54, NO. 2 (2007) Particle identification algorithms for the HARP forward spectrometer M. G. Catanesi et al, Nucl.Instrum.Meth. A521: 899-921 (2007) The HARP Detector at the CERN PS G. Catanesi et al Nucl. Instrum. Meth. A571: 527-561 (2007), 564-573(2007) V. Ammosov et al, Nucl. Instrum. Meth. A571: 561-564 (2007) Momentum scale in the HARP TPC G. Catanesi et al arXiv:0709.2806v1 [physics.ins-det], submitted to JINST The Time Response of Glass RPCs to Heavily Ionizing Particles A.Artmonov et al, arXiv:0709.3756 [physics.ins-det], submitted to JINST In preparation : On the HARP TPC Dynamic Distortion : A Bagulia et al.

9. HARP progress SPSC October 2007 Alain Blondel 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, hep-ex/0702024v2 to appear in Eur. Phys. J. C In preparation: Charged pion production by 3 GeV/c-12 GeV/c protons on a carbon target (Atmospheric Flux) M.G. Catanesi et al, to be submitted to Astr. Part. Measurement of the production cross-section of negative pions in the collision of 8.9 GeV/c protons on beryllium (MiniBooNE target measurement for antineutrinos) M.G. Catanesi et al, draft in preparation

10. HARP progress SPSC October 2007 Alain Blondel FORWARD ANALYSIS

11. HARP progress SPSC October 2007 Alain Blondel p(GeV/c) θ(rad) region of interest for MiniBooNE momentum res. from data. - empty target (beam particles) - p vs beta(TOF) - elastics in H2

12. HARP progress SPSC October 2007 Alain Blondel PID principle CERENKOV TOF CAL TOF CERENKOV

13. HARP progress SPSC October 2007 Alain Blondel

14. K2K Flux prediction for near and far detectors and far/near ratio note improvement over existing data errors are smaller and safer

15. HARP progress SPSC October 2007 Alain Blondel no oscillation flux*0.6 best osc. fit Reconstructed « single ring » Quasi-elastics in SuperKamiokande ==> spectral shape + normalization show oscillation (no oscillation curve for demonstration only) K2K final results (using HARP input, 4.1 -> 4.4  C.L. improved by factor 3) K2K results (incl. HARP) M. H. Ahn et al., K2K Collaboration, Phys. Rev. D74 (2006) 072003

16. HARP progress SPSC October 2007 Alain Blondel HARP Be 5% 8.9 GeV/c Results 0.75<p<5 GeV/c 30<theta<210 mrad Crucial for MiniBooNE which has no near detector! + SciBooNE to measure cross-sections around 500-900 MeV neutrinos (region of interest for T2K)

17. HARP progress SPSC October 2007 Alain Blondel HARP Be 8.9 GeV/c data Sanford-Wang parametrization

18. HARP progress SPSC October 2007 Alain Blondel Systematic errors here: forward 8.9 GeV/c Berylium (MiniBooNE) improvements in -- tertiary interactions (use our own pC and  C data) -- PID Al data

19. HARP progress SPSC October 2007 Alain Blondel comparison of Be with existing data

20. HARP progress SPSC October 2007 Alain Blondel  - data needed for MiniBooNE antineutrino flux Panman

21. HARP progress SPSC October 2007 Alain Blondel More HARP data for accurate flux predictions coming: K± production data thick targets π - production data main source of ν e flux for MiniBooNE Direct measurement with rescattering and absorption Anti-neutrino flux measurement  K p

22. HARP progress SPSC October 2007 Alain Blondel Atmospheric neutrino fluxes : the Harp contribution 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 O 2, N 2 primary flux decay chains N 2,O 2 hadron production  

23. HARP progress SPSC October 2007 Alain Blondel p+C @ 12 GeV/c    leading particle effect stat.  syst. errors ●   ○   log scale Draft in preparations

24. HARP progress SPSC October 2007 Alain Blondel Model comparison: p+C→  + +X

25. HARP progress SPSC October 2007 Alain Blondel Model comparison: p+C→   +X

26. HARP progress SPSC October 2007 Alain Blondel   +C    @ 12 GeV/c (lower statistics)

27. HARP progress SPSC October 2007 Alain Blondel   +C @ 12 GeV/c (high statistics)

28. HARP progress SPSC October 2007 Alain Blondel Preliminary results for O 2 N 2 cryo targets available

29. HARP progress SPSC October 2007 Alain Blondel LARGE ANGLE ANALYSIS

30. HARP progress SPSC October 2007 Alain Blondel HARP publications Large Angle analysis (Neutrino Factory measurements) Measurement of the production of charged pions by protons on a tantalum target M.G. Catanesi et al, Eur. Phys. J. C51 (2007) 787 Large-angle production of charged pions by 3 GeV/c–12 GeV/c protons on carbon copper and tin targets M.G. Catanesi et al, submitted to Eur. Phys. J. C Large-angle production of charged pions by 3 GeV/c–12 GeV/c protons on a beryllium, aluminum and lead targets: M.G. Catanesi et al, submitted to Eur. Phys. J. C In preparation : Large-angle production of charged pions in the HARP expriment with incident protons on nuclear target : M.G. Catanesi et al. (Draft in preparation ) FULL SPILL analysis (beams 3 GeV/c -12.9 GeV/c, Al, Be,C, Cn, Pb,Sn,Ta targets) Large-angle production of charged pions in the HARP expriment with incident pions on nuclear target : M.G. Catanesi et al. (Draft in preparation ) FULL SPILL analysis (beams 3 GeV/c -12.9 GeV/c, Al, Be,C, Cn, Pb,Sn,Ta targets)

31. HARP progress SPSC October 2007 Alain Blondel The TPC surprises -- cross-talk -- dead channels -- static distortions (E-field mismatch) --> EXB effects -- dynamic distortions (E-field build up) ibid -- B-field distortions... The RPC surprise -- observed sensitivity to particle dE/dx beyond standard time-walk correction

32. HARP progress SPSC October 2007 Alain Blondel “Large Angle” analysis beam momenta: 3, 5, 8, 12 GeV/c events: require trigger in ITC (cylinder around target) TPC tracks: >11/20 points, momentum measured and track originating in target PID selection of pions for 100-800 MeV/c additional selection to avoid track distortions due to ion charges in TPC: first part of spill (30-40% of data kept, correction available for future improvement) Corrections: Efficiency, absorption, PID, momentum and angle smearing by unfolding method (same as pC data analysis in forward spectrometer) Backgrounds: secondary interactions (simulated) low energy electrons and positrons (all from  0 ) predicted from  + and  - spectra (iterative) and normalized to identified e +-.

33. HARP progress SPSC October 2007 Alain Blondel Determination of corrections -- cross-talk, dead channels and equalization: from TPC tracks -- static corrections special study during 2003 cosmic run with dedicated 'beam' scintillator finger -- dynamic corrections observed since first days from signed impact parameter distribution momentum bias correlated with d0 develop model model of charge build-up based on recorded events

34. HARP progress SPSC October 2007 Alain Blondel Benchmarks -- cosmics were used to optimize the momentum resolution by comparing the two halves of through-going muons -- high dE/dx region for protons (7-8 MIPS) was used as a momentum benchmark for 340 MeV/c particles -- Main benchmark is elastic scattering data in LH 2 runs allows determination of momentum scale, bias, efficiency -- also, study of RPCs for heavily ionizing particles

35. HARP progress SPSC October 2007 Alain Blondel LA Spectrometer performance: benchmarks momentum resolution  -p PID with dE/dx  -e PID with dE/dx momentum calibration: cosmic rays elastic scattering PID: dE/dx used for analysis TOF used to determine efficiency elastic scattering: absolute calibration of efficiency momentum angle (two spectrometers!)

36. HARP progress SPSC October 2007 Alain Blondel cryogenic H2 target

37. HARP progress SPSC October 2007 Alain Blondel missing mass peak from large angle proton track (position of peak verifies momentum scale -- +15% shift is completely excluded) The elastic scattering benchmark efficiency Comparison of predicted vs measured track allows LA tracking benchmark momentum scale [1/p (predicted-measured)]/(1/p)

38. HARP progress SPSC October 2007 Alain Blondel Stability from LH2 target to other targets consider average momentum of protons with dE/dx  [7-8] MIPs H2 setting  2% Al 13 12 8 5 3 Be 12 9 8 5 3 Carbon 12 8 5 3 Copper 12 8 5 3 H2 Lead 12 8 5 3 Tin 12 8 5 3 Ta 12 8 5 3

39. HARP progress SPSC October 2007 Alain Blondel RPC response to low energy protons RPCs are calibrated with  ~1 particles (pion, electrons) and time-walk correction applied protons exhibit a shift from th. curve ?? claim was made (RBH, Ammosov et al) that this reveals a momentum bias (from a sagitta error)

40. HARP progress SPSC October 2007 Alain Blondel Investigation of RPC effect using elastic scattering H2 -- elastic scattering data @ 5 GeV -- use predicted momentum from elastic scattering kinematics -- calculate expected arrival in RPCs and compare with data observation of a clear shift ! => RPC calibrated for pions cannot be used for momentum benchmark with protons!!! Hydrogen, 5GeV/c, from kinematics pad row 3

41. HARP progress SPSC October 2007 Alain Blondel

42. dynamic distortions dynamic distortions had been first observed in 2003 by d0-curvature correlation 1/  Q*d 0 d0 event number in spill d0 before static corr after static corr

43. HARP progress SPSC October 2007 Alain Blondel For the analysis of the LA HARP data showed until now we used about 1/3 of the data. This statistical sacrifice was due to the presence of dynamic distortions caused by build up of ion-charge density in the drift volume during the 400 ms beam spill, caused by a partial 'transparency' of the cathode wire grid. A pragmatic approach was chosen: we limited our analysis to the early part of the beam spill where the effects of the dynamic distortions in the TPC are still small (more than 30% of available statistics). This choice does not have important consequences on the final data analysis since the cross-section measurements are limited by systematical and not by statistics. Nevertheless the use of the full statistics allows more refined analyses. We have developed a full spill TPC calibration, derived from first principles, based on the influence that positive ions have on the drift The results for all the beam energies and all thin targets are now available. The preparation of the corresponding papers is in progress LA Analysis improvements

44. HARP progress SPSC October 2007 Alain Blondel Pion production yields p-Ta  + forward 0.35 <  < 1.55 backward 1.55 <  < 2.15 p

45. HARP progress SPSC October 2007 Alain Blondel p-Ta   forward 0.35 <  < 1.55 backward 1.55 <  < 2.15 Pion production yields

46. HARP progress SPSC October 2007 Alain Blondel In a first round of publications we used begin of fill data only (~1/3 of data)

47. HARP progress SPSC October 2007 Alain Blondel 3 GeV/c 5 GeV/c 8 GeV/c 12 GeV/c 400 MCHF question: is 5 GeV/c (4 GeV kin energy) enough for the high intensity proton driver at CERN? (or elsewhere) Neutrino factory optimization

48. HARP progress SPSC October 2007 Alain Blondel Neutrino factory study d  /d  cross-sections can be fed into neutrino factory studies to find optimum design Warning the above has fixed integration range, but optimization may be momentum dependent yield/E kin + - + -

49. HARP progress SPSC October 2007 Alain Blondel MARS seems -- too optimistic for   -- too pessimistic at low energy p on Tantalum pion/(proton.(kinetic GeV)) HARP HARP (full) vs MARS (dotted)-- absolute scale uncertain Preliminary! MARS data courtesy S. Brooks

50. HARP progress SPSC October 2007 Alain Blondel π-/π+ ratios for light and heavy nuclei

51. HARP progress SPSC October 2007 Alain Blondel forward production only 0.35 <  < 0.95 rad comparison of   and   and yields for p-A for Be, C, Cu, Sn, Ta and Pb   Pion yields

52. HARP progress SPSC October 2007 Alain Blondel A-dependence of   and   and yields for p-A for Be, C, Cu, Sn, Ta and Pb (3, 5, 8, 12 GeV/c)   A-dependence of Pion yields

53. HARP progress SPSC October 2007 Alain Blondel In H2 elastic scattering events it is possible to compare the predicted recoil to the observed one ==> direct measurement of dynamic distortions!!! a model can be developped

54. HARP progress SPSC October 2007 Alain Blondel LA Analysis: Full spill corrections A phenomenological model has been developed and coded basing of the fact that the force acting on each drift electron is equivalent to: a field system where ions, in a given angular section at R values internal to the drift electron position, contribute to attract the drift electrons inwards a field system where ions, in a given angular section at R values external to the drift electron position, contribute to attract the drift electrons outwards This model allows us to understand all the peculiar features of the TPC dynamic distortions: The dependence of the distortion on the event number in spill The dependence of the distortion on tracks generated at different Z values in the TPC The Model has been developed and benchmarked as well the correction algorithm π-π- π+π+ before after ns d0

55. HARP progress SPSC October 2007 Alain Blondel The model eliminates the event-in-spill dependence

56. HARP progress SPSC October 2007 Alain Blondel p-Ta π whitout and with Dyn. Dist. Corrections

57. HARP progress SPSC October 2007 Alain Blondel Ratio of π+π- X-sections measured with and whitout the dynamic distortion corrections

58. HARP progress SPSC October 2007 Alain Blondel Conclusions HARP has taken a comprehensive set of data and we are producing pion production cross-sections with errors in the 4-8% range over a large fraction of phase-space All DSTs are now ready for production pion cross sections for all targets and all beam momentum. Verification and publication of these results will require a lot of time and labor. Forward analysis for K2K and MiniBooNE has been important ingredient for the understanding of the neutrino fluxes Forward Kaon production cross-sections remain to be produced are eagerly awaited

59. HARP progress SPSC October 2007 Alain Blondel In the large angle region hard work for 5 years led to a good understanding of the chamber using experimental input. Extensive benchmarking of elastic scattering ensures a correct momentum scale at the level of  3% in the kinematic region relevant for pions. The data relevant for the choice of proton driver for a neutrino factory have been published. Mission accomplished. The large angle analysis using the full spill is ready and producing results.

60. HARP progress SPSC October 2007 Alain Blondel Comments on the RBH report and subsequent situation We do not agree with these statements. we have produced 2 papers describing in detail our comments Momentum scale in the HARP TPC G. Catanesi et al arXiv:0709.2806v1 [physics.ins-det], submitted to JINST The Time Response of Glass RPCs to Heavily Ionizing Particles A.Artmonov et al, arXiv:0709.3756 [physics.ins-det], submitted to JINST

61. HARP progress SPSC October 2007 Alain Blondel field reversal makes no visible difference that RBH expected..but shouldnt!

62. HARP progress SPSC October 2007 Alain Blondel Investigation of RPC effect using elastic scattering H2 -- elastic scattering data @ 5 GeV -- use predicted momentum from elastic scattering kinematics (NO TPC!) -- calculate expected arrival in RPCs and compare with data observation of a clear shift ! => RPC calibrated for pions cannot be used for momentum benchmark with protons!!! Hydrogen, 5GeV/c, from kinematics pad row 3

63. HARP progress SPSC October 2007 Alain Blondel Once corrected for the resolution effects near the physical boundary (given by the need of the track to reach the TPC) the RPC Dt shift in LH2 data is consistent with the RPC shift in the other settings Al 13 12 8 5 3 Be 12 9 8 5 3 Carbon 12 8 5 3 Copper 12 8 5 3 H2 Lead 12 8 5 3 Tin 12 8 5 3 Ta 12 8 5 3

64. HARP progress SPSC October 2007 Alain Blondel the proton momentum in the high dE/dy region is independent of polar angle. (total momentum determines dE/dx) This would not be the case for a sagitta bias which affects transverse momentum

65. HARP progress SPSC October 2007 Alain Blondel In essence the interpretation of the RBH was that because of residual uncorrected dynamic distortions, the LH2 momentum calibration would be inapplicable to the rest of the data which would show a systematic difference from H2. This is implausable but...not a priori impossible. further findings... 1. the momentum calibration using full spill dynamic corrections is not modified at all; residuals (as requested by RBH) of tracks physically fixed to RPC show no significant trend. 2. The other sensitive indicators of momentum calibration (high dE/dy protons for instance) show complete agreement between H2 data and the rest.

66. HARP progress SPSC October 2007 Alain Blondel

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

68. HARP progress SPSC October 2007 Alain Blondel Concerning dE/dx: conclusion is not quantitative and no systematic error was assigned to the claim of 15% (±??) at 600 MeV/c (Dp/p is 25% at 1 GeV). Analysis should be done very carefully taking into account binning and resolution, and possibility of both scale and offset factors. We do not consider this to be conclusive

69. HARP progress SPSC October 2007 Alain Blondel Having demonstrated the correctness of the LH2 benchmark both with and without dynamic corrections the stability of the momentum scale to other settings, and the existence of a genuine RPC time bias for heavy ionizing particles We consider confident that our TPC momentum scale is correct within the quoted errors

70. HARP progress SPSC October 2007 Alain Blondel Further steps 0. we believe that these discussions should take place Within the framework of the HARP collaboration 1. it is not clear to us what the extent of the real discrepancy between the CDP and HARP analyses is. This should be established on the basis of a track-by-track comparison (on going) 2. the effect of such a possible bias on the relevant cross-sections should be established! (how important is all this?)

71. HARP progress SPSC October 2007 Alain Blondel Comments on the RBH report and subsequent situation Issue of intellectual property: in the process we gave description of our findings, only to find them later in CDP work (RPC effect, dynamic distortion cross-over, elastic scatt.) with no reference to work of collaborators From the later work on dE/dx, RPC, negative B polarity analysis we have to conclude that the results of the RBH review which were unplausible are now most probably incorrect. There is not a 15% offset in HARP momentum reconstruction at 600 MeV/c