1 / 23

Q 13 measurement with JHF- n

Q 13 measurement with JHF- n. F.Sánchez Universitat Autònoma de Barcelona IFAE. Disclaimer The talk is mainly based on the JHF- n proposal (Y.Itow et al., hep-ex/0106019 ) My only contribution is the compilation and some updated plots. JHF- n. Off-axis conventional beam E n < 1 GeV.

joben
Download Presentation

Q 13 measurement with JHF- n

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Q13 measurement with JHF-n F.Sánchez Universitat Autònoma de Barcelona IFAE

  2. Disclaimer • The talk is mainly based on the JHF-n proposal (Y.Itow et al., hep-ex/0106019 ) • My only contribution is the compilation and some updated plots.

  3. JHF-n Off-axis conventional beam En < 1 GeV. Base line of 295Km to SuperKamiokande. JHF (Japan Hadron Facility) High intensity proton accelerator 50 GeV 0.75 MW (to be proven!) High intensity neutrino flux with <En>~ 0.7GeV at maximumof the nm-nt oscillation for Dm223~0.003 eV2

  4. JHF-n beam Primary Proton beamline Japan Hadron Facility is a multipurpose p accelerator covering items from CP violation in K, hyperon production to nuclear physics. Target Station Relevant parameters for n beam Decay Volume m pit SK Beam Axis 130day/year x 3.3 1014 ppp x 2.5 104p/day ~ 1021pot/year 50GeV PS

  5. Far Det. q Decay Pipe Target Horns OA1° nm OA2° OA3° Off-axis n beam • In a two body decay: • p->nm m • Almost monochromatic beam. • Higher n flux at the maximum of the oscillation than wide band option.

  6. Off-axis n beam Maximum n energy as a function of the off-axis value JHF

  7. Beam Monte Carlo simulation • All calculations are done with a simple two horns GEANT simulation with a long decay pipe (80m). • Includes m polarization. HORN 2 HORN 1 Similar to K2K. Notoptimized!!!

  8. Neutrino energy spectra for 2º off-axis Main contribution: p→m n K→mn contributes to the large energy tails, nm It was 0.033GeV for p ne • Intrinsic ne does not “peak”. Originated from 3 body decays: • m→enenm • K+e3 and Kºe3 contributing to the large energy tails.

  9. Neutrino Fluxes Neutrino flux for En < 1.2 GeV (> 1.2 GeV) ne background below 1%. Similar spectra in all cases (mainly from the m 3-body decay). • Similar flux in the region of interest but: • Flatter for lower off-axis values (lower sensitivity). • Higher flux in WBB above 1.2 GeV (higher backgrounds from NC & CC production).

  10. Normalizing the n flux: close detector In the K2K case, the claim is 5% systematic from normalization. • To normalize the n flux an off-axis detector at 2km is planned (1 KTon water Čerenkov detector –100 Ton fiducial volume-). • Standard problem of different angular coverage between far and close is diluted by beam dispersion: Angle from the p beam to SK.

  11. Normalizing the n flux Similar n energy spectra in both the close and far detectors. In the region of interest, deviations are below 1%. Unexpected similar result for ne. (mainly from 3-body decays)

  12. Normalizing the n flux • Other functionalities of 2km detector • Measurement of neutrino cross-section: • Neutral current. • Charge currents quasi-elastic and non-quasi-elastic. • Interaction topologies and multiplicities: • single p±/p0 production. • Measurement ne contamination. • The 2km detector will be probably similar to the K2K experiment: • water Čerenkov detector. • fine grained calorimeter. • m spectrometer.

  13. nm disappearance I: En reconstruction • En < 1 GeV, mainly Quasi-elastic interactions: nm n → p m • Energy of neutrino can be recovered: • m energy resolution: 3%. • m angular resolution: 3º. • Observation of the oscillation dip →Good resolution in Dm223 → Confirmation of oscillation. • Resolution limited by: • Fermi motion (smearing of ~200 MeV). • Non-QE background subtraction. • Coherent nuclear effects (Nucleus as a target). • Energy shape prediction.

  14. Quasi elastic events in JHF-n JHF off axis Reconstructed vs. true energy in SuperKamiokande for QE events (no Fermi motion). Fraction of QE provided by Nuance Monte Carlo.

  15. nm disappearance I: En reconstruction • En < 1 GeV, mainly Quasi-elastic interactions: nm n → p m • Energy of neutrino can be recovered: • m energy resolution: 3%. • m angular resolution: 3º. • Observation of the oscillation dip →Good resolution in Dm223 → Confirmation of oscillation. • Resolution limited by: • Fermi motion (smearing of ~200 MeV). • Non-QE background subtraction. • Coherent nuclear effects (Nucleus as a target). • Energy shape prediction.

  16. nm disappearance II: flux normalization • Sensitivity to Q23 enhanced by off-axis technique. • The normalization error is highly suppressed (5% in K2K): • Systematic errors: • Neutrino energy shape uncertainties. • Knowledge of energy resolution in far detector (Far/near resolution comparison). • Non-QE background subtraction.

  17. Principle of Q13 measurement • In the assumption of two maximal mixing (12 and 23) the 1 ↔ 3 oscillation will lead to a ne ↔ nt oscillation which needs of a high energy intense ne beam. • However, there is a subdominant oscillation: nm → ne that can be detected in conventional intense beams. The signature is the appearance ofne. • The number of ne is function of Q13 via: nm nt Dm2 = 0.003 eV2 Sin2Qme = 0.05 En = 0.7 GeV ne

  18. ne appearance: background I • Intrinsic background: • nt CC with t→ enn (En below t threshold). • ne contamination of the beam. ( < 6 ‰ ) • ne appearance from Q12 mixing (~ 1 ‰ )→ • The signal is expected to be small, so the background will limit the sensitivity to Q13. Q13=0 First maximum nm ne

  19. e m g g ne appearance: background II Detector related backgrounds • p0 →e misidentification. • p0 identification from 2 Č. rings. • Background: • Missing ring • Overlapped ring. m/p→e misidentification. Id. from ring shape arguments. data 2g invariant mass

  20. ne appearance: background III • p0 →e separation cuts: • Angle between ne and e. (p0 more forward) • Energy fraction of lower energy ring. • Double ring likelihood (low energy ring shadowed by light diffusion). • Invariant mass of 2 photons. Tested in the realistic Superkamiokande Monte Carlo

  21. Sensitivity to Q13 in JHF-n: bck estimates From beam simulation and SK Monte Carlo (5 years exposure): Dm2 = 0.003 eV2 Sin2Qme = 0.05 From En range Mainly p from NC QE!!!! In absence of signal: Bck ~ 22 events Expected signal

  22. Sensitivity to Q13 in JHF-n Old result from JHF-n proposal. Sesitivity contour from a full oscillation analysis. Sensitivity is enhanced around the expected value of Dm2 for both off-axis and narrow band beam. • 5 Years (~ 5 1021 pot) • Three options: • Wide Band • OAB 2º • NBB 2 GeV.

  23. Conclusions Superkamiokande is a known-good n detector around 1GeV: Good angular and energy resolution. Good particle id. capabilities. + All accumulated experience. Off-axis technique: maximum sensitivity & low background. energy reconstruction from QE. High intensity proton beam (1012 pot/year). Near (2km) detector: Optimal flux normalization. Characterization of nN interactions at these energies. JHF-n will measure sin2 2 Qme with a sensitivity of 0.003 @ 90% C.L. after 5 years of operation in the appearance of ne from a nm beam. • But!, low energy means: • Low n cross-section. (bad for ne appearance) • Large energy uncertainty from Fermi motion worsening D2m resolution for nm.

More Related