1. Naotoshi Okamura (YITP) 2005/06/22 @ NuFact05
Solving the neutrino parameter　degeneracies by measuring the T2K off-axis beam in Korea
Naotoshi Okamura (YITP)
NuFact05
K.Hagiwara and K.Senda
hep-ph/

2. content short review (8-fold ambiguities)
Tokaimura-to-Kamioka (T2K) experiment
off-axis beam JapanKorea
solve the ambiguities
mass hierarchy
CP phase
Summary

3. Parameters neutrino physics 7/9 parameters neutrino oscillation
neutrino masses
m1 m2 m3
flavor mixing angles
12 23 13
CP phase 
Majorana phases
1 2
squared-differences
m212 m213 (m23-m21)
flavor mixing angles
12 23 13
CP phase 
Majorana phases
nothing

4. 8 fold ambiguities exist
sign of m213
2 fold ambiguity
difficult !!
unknown parameters
2 fold ambiguity
will measure
value of 23
2 fold ambiguity
best fit is 45
8 fold ambiguities exist

5. today’s topic “mass hierarchy” and “CP phase”

6. Tokaimura-to-Kamioka (T2K)
J-PARC (under construction)
Place : Tokaimura (NE-60km from KEK)
50 GeV Proton Synchrotron (1021 POT/year)
neutrino intensity is O(2) higher than that of K2K
Super-K (exist)
Distance : L=295 km
Place : Kamioka
50Kton water Cherenkov detector (fiducial 22.5Kton)
good e/ identification
cannot measure the charge
Plan to use the off-axis beam (OAB)

7. off-axis beam (OAB) E(GeV) 2.0 0.0 2.5 3.0 OAB will go to Korea   
Conventional Super Beam ( from  decay)
From the conservation low
E(GeV)
features of OAB
upper limit of the neutrino energy
reduce the high energy tail
reduce the BG
peak energy --- off-axis angle
tune the peak easily
2.0
0.0
2.5
3.0
OAB will go to Korea
E(GeV)

8. Neutrinos will go to Korea
OAB : cone, umbrella
Super-K
L=295km,
 =2.0-3.0
J-PARC
on-axis
L= km,
 =1.0-4.0
S-Korea

9. angle in Korea depends on that at SK
which combination ??
angle in Korea depends on that at SK
Optimization :where in Korea
which angle in Korea/SK ??

10. Condition fiducial volume exposure time base-line and off-axis
SK : kton
Korea : kton
exposure time
5 years with 1021 POT/year
T2K running time
base-line and off-axis
SK: L=295km with =2.5o / 3.0o
KR: L= km with =(0.5o - 3.0o) / 0.5o
Angle in Korea depends on the distance and angle at SK

11. Parameters Solar sin22 = 0.84 0.07, m2 = (8.3  0.6) 10-5 eV2
Atmospheric
sin22 = 1.0 0.04, m2 = (2.5  0.5) 10-3 eV2
matter density (uncertainty : 3%)
 = 2.8 / 3.0 (g/cm3) (SK/Korea)
others (uncertainty : 3%)
flux normalization (each species)
CCQE cross section ( / anti-)
fiducial volume (SK / Korea)

12. event number (1) CCQE event easy reconstruct the neutrino energy
easy distinguish, e-like, -like
binning
bin width : 200MeV
summation region (#event > 10)
0.4 – 5.0 GeV for -like (SK/Korea)
0.4 – 1.2 GeV for e-like (SK)
0.4 – 2.8 GeV for e-like (Korea) BG
beam contamination
Not include NC background

13. event number (2) event number (  ) true : fit :  E:200MeV
depends on the
matter density: f (L)
true :
fit :

14. 2 - rule of the game - event numbers systematic errors parameter

15. Best Place in Korea true : “normal” fit : “inverted”
true : sin2213= 0.1  free : fit
 = 0.0  free
Best Place : L=1000km with 0.5o and

16. Q : Where is the best ?? A : east coast of Korea = 0.5o L = 1000 km
with
 =
A : east coast of Korea

17. hierarchy
We can distinguish the mass hierarchy with 1OAB – 2Detectors exp., if we are lucky.
(true : sin2213 > 0.06)
Optimized combination
L=1000km with 0.5o (vicinity of here)
L=295km with 3.0o
2  16 (4) (true : sin2213 =0.1, =0.0o)

18. CP phase
distinguish

19. KJ experiment summary 3 type ambiguities
“mass hierarchy”, “CP phase + 13”, “sin23”
T2K + Korea (1.OAB - 2.Detectors)
L=295km OA:3.0 and L=1000km OA:0.5
with reactor experiment
we get them
mass hierarchy : 2 > 9 (sin2213  0.06)
CP phase : 0180 (sin2213  0.06)
KJ experiment

20. END