T2KK sensitivity as a function of L and Dm2 Kimihiro Okumura (ICRR Univ. of Tokyo) 2nd International Workshop on a Far detector in Korea for the J-Parc Neutrino Beam

Introduction Merit of Korea detector: larger CP phase effect by a factor of 3 large energy dependence of P(nmne) vs P(nmne) Distance from the target (km) SK/HK 295km Korea ~1000km JPARC 2.5deg.off-axis beam @Kamioka K. Hagiwara Nucl. Phys. Proc. Suppl. 137 84 (2004) Off-axis angle

Expected physics for T2KK Ishitsuka et al. PRD72 033003 (2005) Mass hierarchy CP violation 4MW 2.5deg OA beam 4yr for n Kamioka only 0.54Mton Kam+Korea 0.27+0.27Mton Mass hierarchy can be determined for sin22q13>0.055 (3s) for any d Sensitivity for CP violation is kept or enhanced for sin22q13>~0.01

T2KK sensitivity study We have investigated optimized conditions for mass hierarchy and CP violation sensitivities: Previous studies: detector mass ratio of Kamioka and Korea detectors  1:1 neutrino & anti-neutrino running time  4yr + 4yr uncertainties due to matter density, detector systematic error, sin2q23 Updates for this conference: baseline length (L) uncertainty due to Dm232　 beam off-axis angle  this talk  Fanny’s talk

Improvement of analysis method 　 　　　Analysis method is based on that used in previous　analysis, but some improvements has been added: detector energy response (Eture  Erecon) using matrix method flux spectrum shape for Korea detector energy-dependence in ne CC non-QE interaction

Calculation of P(nmne) signal spectrum CC QE CC non-QE f(En) : neutrino beam spectrum s(En) : cross section e(En) : event selection efficiency S(En, Enrecon) : detector response function Analytical calculation is adopted with consideration of selection efficiency and energy response of SK

Energy response function ne CCQE ne CCnQE Reconstructed Neutrino Energy True neutrino Energy (GeV) True neutrino Energy (GeV) Energy response of detector is precisely introduced using matrix method for CCQE and CC non-QE respectively

Procedure of making signal spectrum nm  ne oscillation probability X efficiency X neutrino flux X cross section event spectrum w/o smearing detector response CC QE event spectrum w/ smearing CC non-QE binning analysis histogram

c2 calculation nm CC and NC background events are considered five energy binning for spectral analysis 400-500, 500-600, 600-700, 800-900, 900-1200MeV systematic error 5% signal&BG normalization, 5% energy spectrum

Sensitivity as a function of baseline length Tested points: L = 1000~1250 km 50km interval 6 points beam off-axis angle is fixed to 2.5 degree for both Kamioka and Korea Dm122=8.0x10-5eV2 Dm232=2.5x10-3eV2 sin2q12=0.31 sin2q23=0.5 4MW, 4yr for n + 4yr for n 0.27 + 0.27 Mton fiducal

baseline dependence of mass hierarchy and CP violation 3s contour mass hierarchy CP violation Preliminary normal true:normal Kamioka only Inverted true:inverted baseline length dependence of mass hierarchy is small for large fraction of d

baseline dependence of mass hierarchy and CP violation mass hierarchy Preliminary Inverted normal mass hierarchy normal Inverted CP violation

2.5deg OA beam neutrino run normal hierarchy spectrum @ Korea 4MW 4year 0.27Mton 2.5deg OA beam neutrino run normal hierarchy sin22q13=0.02 d=0 sin22q13=0.02 d=p Oscillation Probability signal spectrum (w/o detector response) signal spectrum (w/ detector response) Neutrino energy (MeV) Neutrino energy (MeV)

Sensitivity as a function of Dm2 Tested points: 6 points in 2.0~3.0 10-3 eV2 3.010-3 eV2 2.010-3 eV2

Dm2 dependence of mass hierarchy and CP violation Preliminary mass hierarchy CP violation 3s contour normal normal Inverted Inverted

CP violation: little dependence Dm2 dependence of mass and CP violation sensitivity normal Inverted mass hierarchy: sensitivity at Dm2=2.010-3eV2 is best. difference is within factor of 3 CP violation: little dependence normal Inverted Preliminary

2.5deg OA beam neutrino run Dm232=2.5x10-3eV2 sin22q13=0.02 d=p Korea 4MW 4year 0.27Mton 2.5deg OA beam neutrino run Dm232=2.5x10-3eV2 sin22q13=0.02 d=p Oscillation Probability signal spectrum (w/o detector response) signal spectrum (w/ detector response) Neutrino energy (MeV)

Summary Mass hierarchy and CP violation sensitivities in T2KK were investigated as a function of baseline length and Dm2 parameter Dependence in baseline length is small for math hierarchy sensitivity for large fraction of d. Difference of sensitivity due to Dm2 is within factor of 3 for 2.0~3.010-3 eV2. For CP violation sensitivity, there is little dependence of Dm2 and baseline length.