Claudia Strabel, ETH Zurich SPS Annual Meeting June 21 – 22, 2010 Hadro-production measurements for T2K with NA61/SHINE at the CERN SPS

Outline Physics Goals (T2K) NA61/SHINE Detector Inelastic X-Section    and   Results Summary and Outlook Claudia Strabel, CERN SPS Grandmother (beam particle) Mother (secondary particle)  Search for Critical PointCosmic-Ray Air Showers Pierre Auger + KASCADE -Beam Characterization T2K A+A collisions p+C,  +C collisions p+C collisions NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) 130 scientists from 25 institutes and 14 countries

 One of the main physics goals of NA61/SHINE:  JPARC (Japan): - Long baseline (295km) neutrino oscillation experiment o Search for and measurement of the  → e appearance »  13 o Refinement of  disappearance measurements »  23 and  m Protons (30GeV) + carbon target (90cm) → intense   beam (~0.5% e  contamination in oscillation peak region) - Neutrino spectra measured 2.5° off-axis at the near and far detectors: ND280 and SK - oscillations probed by comparing the flux measured at SK to the one predicted at SK p  2.5° SK ND Precision measurements of hadron production for the prediction of -fluxes at T2K Physics Goals (I) ND280SK 30GeV

 To predict the flux at SK one uses the near detector measurements and extrapolates them with the Far to Near (F/N) ratio (R  e ) to SK Physics Goals (II) Claudia Strabel, CERN SPS  Poor knowledge of hadron production spectra leads to uncertainties in the calculation of R  e and consequently uncertainties in the predicted far detector spectrum  For more precise predictions measurements of  and K production off the carbon target are essential  The aim of the NA61/SHINE measurements for T2K is to: - measure   spectra with a typical precision of 5% - measure K + /   ratio with an uncertainty of 10% → Predict Far/Near neutrino flux ratio to 3%  To reach this precision ~200k reconstructed   tracks in p+C interactions are needed  Furthermore,   and K + from secondary interactions in the T2K target are being measured Preliminary

NA61/SHINE – Fixed Target Experiment at CERN SPS Claudia Strabel, CERN SPS 2009/11 He BEAM PIPE 2007/11 PSD Large acceptance spectrometer: 5 TPCs 2 dipole magnets  (p)/p 2 ≈ (GeV/c) -1  (dE/dx)/ ≈ ToFs  (ToF-F) ≈ 120 ps  (ToF-L/R) ≈ 60 ps High quality of data reconstruction p + C (LT), 31 GeV/c  + measured in NA61 MC  + producing in SK

 Secondary hadron beam composed of 83.7%  +, 14.7% p and 1.6% K +  Proton beam particles identified by CEDAR (C1) and threshold Cerenkov counters (C2)  Incoming p then selected by several scintillator counters (S1, S2, V0, V1) → beam defined as B = S1S2VC1C2  Trajectory of beam particles measured by the beam position detectors (BPD-1/-2/-3)  Interactions in the target selected by anti-coincidence of the beam particle with a small scintillator S4 (BS4) Setup of Beam Line Claudia Strabel, CERN SPS Beam MomentumBeam Spot at BPD3Triggered Protons (C1 C2)All Beam Particles  p  p 2007 Data

Thin Carbon Target T2K Replica Target Target and Data Samples Claudia Strabel, CERN SPS  2 different carbon targets (isotropic graphite,  = 1.84 g/cm 3 ): T2K Replica Target Ø= 2.6cm x 90cm interaction length ~1.9 to study all particles produced in T2K target (primary + secondary)  Interactions registered for T2K with 30.9 GeV/c protons: Target InReplica TargetTarget Out k230k80k 2009 ~ 4M ~ 2M ~ 500k → first preliminary hadron spectra for T2K have been obtained with 2007 thin target data → work on 2007 T2K Replica Target data has started → calibration of 2009 data about to be finalized Thin Carbon Target 2.5 x 2.5 x 2cm 3 interaction length ~0.04 to evaluate p+C nucleus x-section (w/o reinteractions)

-For the thin target data the goal is to present data in terms of yields and inclusive cross sections -Experimentally, the differential inelastic cross section can be expressed in the following way  : density, L: length, N A : Avogadro const., A: Atomic number, N beam : # of incoming beam particles, N trig : # of triggered evts coming from the target -Several steps for normalization and correction needed Inelastic and Trigger Cross Section Claudia Strabel, CERN SPS  Correct  trig for the exponential beam attenuation in the target with L eff : effective length abs : abs. length 2)Correct  trig for distortions due to events outside of the carbon target with ≈ 3)Correct the particle yield ∆n/N trig for distortions due to events outside of the carbon target with

Interaction Probabilities and Trigger Cross Section Claudia Strabel, CERN SPS Target In Target Out P int Tin [%]P int Tout [%]P int Tin-out [%]  trig [mb] ± ± ± ± ± ± ± ± 0.7 Target In Target Out TI: TO: TI TO Rescaled error on P int by sqrt(  2 /NDF)

  inel can be obtained from the  trig by applying the following corrections: 1) Subtract the contribution of elastic interactions (  elastic ) due to large angle coherent scattering 2) Add the contribution of lost events where a secondary particle hits S4. Here, the major contribution comes from quasi-elastic scattering of the incident protons (  loss  p ) Also secondary pions or kaons hitting S4 have to be taken into account (  loss  ) → Corrections have been estimated with Geant4 simulation Corrections to compute the Inelastic Cross Section Claudia Strabel, CERN SPS Systematic error: - on  trig has been estimated by recalculating  trig after offline event selection - on  loss−p,  loss−  /K and  elastic has been evaluated by varying the S4 position in the GEANT4 simulation - on  elastic furthermore includes the discrepancy between the GEANT4 value and the experimental measurement from “G. Bellettini et al., Nucl. Phys. 79 (1966) 609“ * value based on 2007 data *

→ Preliminary NA61 value for  inel is in agreement with some previous measurements Comparison of Inelastic Cross Sections syst. error stat. error  Preliminary NA61 value on  inel can then be compared to previous p+C cross section measurements -G. Bellettini, Nucl. Phys. 79 (1966) 609 :  inel =  tot –  elastic at 20 GeV -A. Carroll, Phys. Lett. B80 (1979) 319:  meas =  tot –  elastic –  qe at 60 GeV → to obtain our definition of  inel we did  meas +  qe (20 GeV) -S.P. Denisov, Nucl. Phys. B61 (1973) 62:  meas at 20/30/40/50/60 GeV not clear if  qe has been subtracted or not (need to contact authors to clarify) Claudia Strabel, CERN SPS Fitted in range [10,100]GeV/c To calculate  qe (E) the following approximation has been used:  qe (E) = 1.6 A 1/3  pp (E) with A: Atomic number and  pp : elastic pp cross-section Data from 2008 Review of Particle Physics [ ] 10

Normalized Pion Spectra from Thin Carbon Target (2007 Data) NA61 Preliminary Postersession: Implementation of NA61 data in T2K – N. Abgrall  Normalization to mean multiplicity in inelastic collisions 20% systematic errors -- ++  Particle identification via dE/dx, combined dE/dx + ToF measurements and h - analysis → Spectra are corrected for geometrical acceptance, reconstruction efficiency, weak decays, vertex association and empty target contribution → 18:15 TASK Session: Pion production measurements in NA61 for T2K – S. Murphy

Summary and Outlook Claudia Strabel, CERN SPS  NA61/SHINE is a large acceptance hadron spectrometer at the CERN SPS which will precisely measure particle production from interactions of 30 GeV protons on different carbon targets → Thin target: for the determination of inclusive cross sections → T2K replica target: for the study of secondary interactions in the T2K target  During the 2007 pilot run data on proton-Carbon interactions were registered → good quality of data, though limited in statistics → the data and detailed simulations confirm that phase space needed for T2K measurements is covered →  trig and  inel were measured; preliminary  inel is in agreement with some previous measurements → first preliminary normalized hadron spectra for T2K have been obtained → work on T2K replica target data is in progress  During 2009 physics run 3 weeks were dedicated to T2K measurements → several detector upgrades ( TPC read-out and DAQ → increase of event rate by factor 10 (~70Hz)) → 4M interactions collected for thin carbon target and 2M interactions for the T2K replica target → first estimation of  trig in good agreement with value from 2007