@misc{oai:ir.soken.ac.jp:00000706, author = {泉田, 賢一 and センダ, ケンイチ and SENDA, Kenichi}, month = {2016-02-17, 2016-02-17}, note = {The Tokai-to-Kamioka (T2K) neutrino oscillation experiment will start in 2009.
In T2K. the center of the neutrino beam from J-PARC at Tokai will go through
underground beneath Super-Kamiokande (SK), reach the sea level in the Japan
(east) sea near Korean shore. When the beam center is 2.5°(3.0°) downward SK,
the neutrino beam with an off-axis angle greater than 1.0°(0.5°) can be observed
in Korea. We study the physics potential of the Tokai-to-Kamioka-and-Korea
(T2KK) experiment when an additional 100 kt-level Water Čerenkov detector is
placed in Korea during the T2K experimental period. We find that the matter
effect, which arises from the coherent interaction of Ve (or ‾Ve) off the electrons in
the earth matter, is a powerful tool to determine the sign of (m²₃−m²₁), and the
CP phase, σMNS, of the lepton flavor mixing matrix. The best combination of the
off-axis angles at each detector and the length for the Tokai-to-Korea baseline is
found to be 3.0°at SK ( L = 295 km) and 0.5° at L =1000km. If we choose this
combination, and if the densities along the baselines are 2.8 g/cm³ for Tokai-to-
Kamioka baseline and 3 g / cm³ for Tokai-to-Korea baseline with 3% uncertainties,
the mass hierarchy pattern can be determined at 3-σ level for sin² 2θRCT＞_～ 0.09,
and the CP phase can be constrained with ± 30°error for sin² 2θRCT0.06, after
5 years of running (5 × 10²¹ POT). When we combine the result of the future
reactor neutrino ercperiments, such as Double-CHOOZ, RENO, DAYA-BAY, the
capability of determining the mass hierarchy pattern in T2KK is enhanced, and the
hierarchy pattern can be constrained at 3-σ level for sin²2θRCT＞_～ 0.055. Because
of the importance of the matter effect, we study the matter profile along the
baselines of the T2KK experiment by using the recent geophysical measurements.
The average matter density along the Tokai-to-Korea baselines is found to be 2.96,
3.01, and 3.03 g/cm³ for the baseline length of L = 1000, 1100, and 1200 km,
respectively, with about 6% uncertainty. Only the real part of the first Fourier
mode gives non-negligible but very small contribution to the up vμ→ve oscillation
probability. We find that, even if we enhance the error of the average matter
density from 3% to 6%, the capability of determining the neutrino mass hierarchy
pattern in T2KK does not deteriorate significantly because the measurement error
is dominated by statistics., application/pdf, 総研大甲第1141号}, title = {Physics potential of Tokai-to-Kamioka-and-Korea neutrino oscillation experiment}, year = {} }