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Defining the energy of the proton driver the role of HARP as hadro-production experiment

Defining the energy of the proton driver the role of HARP as hadro-production experiment. M. Apollonio, on behalf of the HARP Collaboration [Univ. of Trieste and INFN]. Overview. The experiment and its goals Status of Analysis Large Angle Region Small Angle (or Forward) Region

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Defining the energy of the proton driver the role of HARP as hadro-production experiment

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  1. Defining the energy of the proton driverthe role of HARP as hadro-production experiment M. Apollonio, on behalf of the HARP Collaboration [Univ. of Trieste and INFN] CERN -Physics with a multiMW proton source- M.Apollonio

  2. Overview • The experiment and its goals • Status of Analysis • Large Angle Region • Small Angle (or Forward) Region • Conclusions & Plans CERN -Physics with a multiMW proton source- M.Apollonio

  3. HARP (PS214) • HAdRonProductionExperiment at PS;(from proposal(1)): • optimize thep+(p-) yieldfor then-factory • calculations ofbeam fluxesforK2KandMiniBoone • input for calculations ofatmospheric neutrino flux • input for Monte Carlohadronic generators [(1) CERN-SPSC/99-35, SPSC/P315, Nov. 15th 1999] CERN -Physics with a multiMW proton source- M.Apollonio

  4. n-factory (but also super-beams) • maximize p+(p-) production yield (/proton/GeV) • optimize: • targetmaterial • protonenergy • collection(pL,pT) • simulations showlarge discrepancies on p yieldanddistributions • Experimental knowledge rather poor: • Small acceptance, few materials tested • Old (Allaby et al., 1970, Eichten et al. 1972) • Aim:p yield (p+/p-)knownbetter than 5%  thick target program: high Z at several p CERN -Physics with a multiMW proton source- M.Apollonio

  5. one of thelargest systematic errors in K2K in then oscillation parameterscomes from the uncertainty on the far/near ratio: depends on p-prod. model used 2.0 1.5 2.5 0 0.5 1.0 n Pp the K2K case qp To be measured by HARP Oscill. MAX • special program with K2K-replica Al target • K2K request: D(F/N)/(F/N) < 3% En (GeV) Beam MC confirmed by Pion Monitor Beam MC CERN -Physics with a multiMW proton source- M.Apollonio

  6. DATA taking campaign: 2001-2002 • P [1.5 GeV/c – 15 GeV/c] • (quasi)full solid angle(1)coverage • widelist oftargets:materials and sizes • fromH to Pb • 2%, 5%,50%,100% l • High event rate: 2.5 kHz (~106 evts/day) [(1) target inside the TPC!] CERN -Physics with a multiMW proton source- M.Apollonio

  7. O(106) events per setting 30 Tbytes of data 420 million events CERN -Physics with a multiMW proton source- M.Apollonio

  8. T9-secondary line @ CERN-PS Large Angle target Small Angle HARP:detector overview CERN -Physics with a multiMW proton source- M.Apollonio

  9. Simulated p from p on Be target (2-15 GeV/c) TPC p/p PID 2 GeV/c 15 GeV/c Ckov p/p PID TPC p/p PID TOF p/p PID TOF p/p PID CERN -Physics with a multiMW proton source- M.Apollonio

  10. calibration/equalisation, based on: • high statistics cosmics • 83Kr -41.6 keV- • 55Fe -5.9,3.0 keV- (2003 campaign) • data • these data have allowed • computation of gains and mapping of dead pads: likely to be done on a run by run basis • first evaluation of dE/dX • first evaluation of the performance of a correction for a cross talk effect • improvement in momentum resolution of 30% • check of the improvements: data with a cryogenic H2 target, 3 GeV/cp’s and protons are being analyzed, looking for elastic scattering: p(),p  p(),p Large Angle:TPC (0.7 T) • TPC coversbasically all the(pL,pT)space at low momenta, (~2 GeV/c), and most of it even at higher momenta (~15 GeV/c) CERN -Physics with a multiMW proton source- M.Apollonio

  11. p p,m dE/dX calibration with radioactive sources drf=1.19 mm cosmics data before x-talk correction after x-talk correction P (GeV/c) 55Fe 83Kr drf=1.51 mm CERN -Physics with a multiMW proton source- M.Apollonio

  12. p missing mass p missing mass Elastic Scattering: p(p)p  p(p)p • Normalization+calibration tool: • measure elastic cross-section • compare with the average cross section from literature (accuracy ~ several percents) • adjust momentum and covariance matrix of all tracks to get right c2 distribution for elastic events • tune MC to get the right elastic cross section Pc Pd 1Gev/c Pa Mx2=(pa+pb-pd)2 CERN -Physics with a multiMW proton source- M.Apollonio 3Gev/c

  13. Small Angle: basically covered by the forward detectors • tracking & momentum measurement: • provided bydrift chambers(from NOMAD)+dipole magnet(1.0 Tm) • PIdgiven by an overlapped combination of: • a thresholdCherenkovcounter • atime of flight • anelectron calorimeter CERN -Physics with a multiMW proton source- M.Apollonio

  14. NDC4 NDC2 NDC1 NDC5 dipole magnet target 1 beam B 2 NDC3 Forward Tracking momentum resolution MC case 1 data CERN -Physics with a multiMW proton source- M.Apollonio

  15. P < 4.5GeV/c p+ light particles 3 GeV beam particles 12.9 GeV K2K thin target p p PId • p/p separation (as a function of P) • P < 4.5 GeV/c: relies on theTOF system Target+TOF-Wall l ta tb tc t0 tw • Tof-W resolution: ~ 160 ps  >7sp/p at 3 GeV • Beam resolution: ~180ps (expected to improve) CERN -Physics with a multiMW proton source- M.Apollonio

  16. 3 GeV/c5 GeV/cbeam particles e+ Nphel p p p+ p inefficiency p inefficiency Th(K): 9.2 GeV/c Th(p): 2.6 GeV/c p+ p+ e+ number of photoelectrons P (GeV/c) • p/p separation • P > 3 GeV/c: relies on a thresholdCherenkov • p/K separation • 3<P<9 GeV/c CERN -Physics with a multiMW proton source- M.Apollonio

  17. Discrimination between electrons and pions is provided by a combination of Cherenkov and Electron Identifier h+ hadrons 12.9 GeV /c K2K thin target 3 GeV/c beam particles small electron contamination e+ CERN -Physics with a multiMW proton source- M.Apollonio

  18. HARP first analysis • Focused on the K2K case • The small angle region covers the (q,p)region relevant for K2K • well known region of the apparatus in terms of • acceptance • PId • efficiency (tracking, matching, PId …) CERN -Physics with a multiMW proton source- M.Apollonio

  19. K2K case (reprise) K2K region of interest • Thin Al (5% l), Pbeam=12.9 GeV/c • Pp>1 GeV/c • |q|<250 mrad CERN -Physics with a multiMW proton source- M.Apollonio

  20. Cross Section: bkg: misidentified p (i,j)=(p,q) normalization:not computed yet p-yield migration matrix: not computed yet Total efficiency CERN -Physics with a multiMW proton source- M.Apollonio

  21. p yield corrected for efficiency results presented in Moriond • The errors reflect the lack of MC statistics • Plots integrated over q and p • No systematic errors included arbitrary units arbitrary units proton background for Tof 3 MC hadron generators IMPORTANT This background can be computed with the data CERN -Physics with a multiMW proton source- M.Apollonio

  22. Conclusions-I • HARP: recorded 420M events in 2 years (2001-2002) • The results shown today (first presented in Moriond) used 1/6 of our K2K thin target data • Forward spectrometer & PId detectors are well understood • MC/Data production “machinery” well under control • Data statistics is not a problem (5.6 M events after data quality) • Small systematic error expected CERN -Physics with a multiMW proton source- M.Apollonio

  23. Conclusions-II • The forward angle analysis shows the potential of the experiment: • 1st cycle to be concluded very soon (full K2K replica, full statistics, systematics, normalization …) • The Large Angle analysis will fully exploit the physics reach of the experiment: • TPC calibration being refined + readiness for analysis • Plans: produce a preliminary result for proton driver energy at Villars workshop CERN -Physics with a multiMW proton source- M.Apollonio

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