1. 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

2. 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 (2004)
Off-axis angle

3. Expected physics for T2KK
Ishitsuka et al.
PRD (2005)
Mass hierarchy
CP violation
4MW
2.5deg OA beam
4yr for n
Kamioka only
0.54Mton
Kam+Korea
Mton
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

4. 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

5. 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

6. 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

7. 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

8. 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

9. c2 calculation nm CC and NC background events are considered
five energy binning for spectral analysis
, , , , MeV
systematic error
5% signal&BG normalization, 5% energy spectrum

10. 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
Mton fiducal

11. 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

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

13. 2.5deg OA beam neutrino run normal hierarchy
Korea
4MW 4year 0.27Mton
2.5deg OA beam neutrino run
normal hierarchy
sin22q13= d=0
sin22q13= d=p
Oscillation Probability
signal spectrum
(w/o detector response)
signal spectrum
(w/ detector response)
Neutrino energy (MeV)
Neutrino energy (MeV)

14. 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

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

16. 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

17. 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= d=p
Oscillation Probability
signal spectrum
(w/o detector response)
signal spectrum
(w/ detector response)
Neutrino energy (MeV)

18. 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.