Takaaki Kajita, ICRR, Univ. of Tokyo
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Takaaki Kajita, ICRR, Univ. of Tokyo
◆Introduction
◆T2KK @TAUP05
◆Updating T2KK
- L dependence, - Higher energy option, - Octant of 23,
◆Summary
TAUP07, Sep.2007, Sendai
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13
13
Sign of m232Sign of m232
CP ?CP ?
3
21
e
If 23 ≠/4, is it >/4 or </4 ?
If 23 ≠/4, is it >/4 or </4 ?
3
oror
e
3
How much will Kamioka-Korea 2 detector setup (T2KK) contribute to these measurements?
sin212, sin2223, m122, =m23
2| ・・・・ Already measured.
Let’s assume that non-zero 13 will be observed by the next generation oscillation experiments.
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Possible experimental setup Possible experimental setup
JPARC0754MW
Off-axis angle
2.5deg.off-axis beam @Kamioka
Distance from the target (km)
2.5 deg. off axis2.5 deg. off axis
2.5 deg. off axis(or smaller off-axisAngle)
2.5 deg. off axis(or smaller off-axisAngle)
Fig. from Senda NP04
0.27Mton0.27Mton
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Osc. probability Osc. probability in in KamiokaKamioka and and KoreaKoreasin2213=0.05sin2213=0.05
BG & efficiency: almost identical both 2.5 deg. off axis beam
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Expected sensitivity Expected sensitivity Total mass of the detectors = 0.54 Mton fid. mass4 years neutrino beam + 4 years anti-neutrino beam
Total mass of the detectors = 0.54 Mton fid. mass4 years neutrino beam + 4 years anti-neutrino beam
3 (thick)3 (thick) 2 (thin)2 (thin)
Mass hierarchyMass hierarchy CP violation (sin≠0)CP violation (sin≠0)
hep-ph/0504026
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Update (1)Update (1)- 1050km: a special baseline ? - - 1050km: a special baseline ? -
2.5 degree off-axis beam with L between1000km and 1250km is available.
Checked if the sensitivity depends strongly on the baseline length.
2.5 degree off-axis beam with L between1000km and 1250km is available.
Checked if the sensitivity depends strongly on the baseline length.
Sensitivity to mass hierarchy(True = normal hierarchy)
sin
22 1
3
The sensitivity does not depend strongly on L !
K.Okumura, 2nd T2KK workshop, Seoul 2006
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Update (2): higher energy optionUpdate (2): higher energy option
T2KK ‘s sensitivity on mass hierarchy is still limited compared with the US studies… Higher energy better ? T2KK ‘s sensitivity on mass hierarchy is still limited compared with the US studies… Higher energy better ?
Mass hierarchyMass hierarchy
3(black)
3(black)
3 (thick)3 (thick)
arXiv:0705.4396
Motivation:
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Higher energy beam Higher energy beam
1.0 to 2.5 degree off axis beam available in Korea.
E (GeV)
Flu
x (a
rb.
unit)
P(
e
)
Energy Dependent Maximum Likelihood
Analysis
Energy Dependent Maximum Likelihood
Analysis
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Signal and BG for various off-axis beams Signal and BG for various off-axis beams
KamiokaKamioka KoreaKorea
2.5 degree 1.0 degree 1.5 degree
2.0 degree 2.5 degree
signal
BG
sin2(213)=0.1 =1/24 year neutrino run4MW beam
Smaller off-axis angle:
Low E BG more serious.
(2nd osc. Max. difficult to see.)
But larger matter effect at the 1st osc. Max..
signal
BG
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33 sensitivities for various OA angles sensitivities for various OA angles
Mass hierarchyMass hierarchy CP violationCP violation
F.Dufour, 2nd T2KK workshop, July 2006, Seoul
(Updated)
Preliminary
Mass hierarchy: OA1.0 @Korea gives the best sensitivity
CP violation: Sensitivity depends weekly on the beam option
Could be slightly too optimistic for OA angle less than 2.5 degrees (The syst errors are assumed to be fully correlated between 2 detectors)
Kam only (OA2.5)Kam + Korea OA1.0Kam + Korea OA1.5Kam + Korea OA2.0Kam + Korea OA2.5
33
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Update (3):Update (3): Octant ambiguity of Octant ambiguity of 2323
In the previous study, maximal 23 mixing (23=/4) was assumed. However, 23 might not be /4. In this case, there should be additional ambiguity in the parameter measurements (especially in that of sin213) due to the ambiguity in the octant of 23 (i.e., 23 >45 or <45 deg.).
It will be very nice if the same setup can solve the octant ambiguity of 23.
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Oscillation probabilities and the signal Oscillation probabilities and the signal P(e) by the solar m2 is proportional to
sin2212 ・ cos223
Solar oscillation effect visible in a very long baseline (or very large L/E) experiment.
P(e) by the solar m2 is proportional to
sin2212 ・ cos223
Solar oscillation effect visible in a very long baseline (or very large L/E) experiment. Solar term
Atm. + CP terms
BG eventssin2212 ・ cos223
effect visible
○sin2 23 = 0.4, sin2 213 = 0.01●sin2 23 = 0.6, sin2 213 = 0.0067(sin223 ・ sin2213 is equal in the two cases.)
m2: positive, =3/4
○sin2 23 = 0.4, sin2 213 = 0.01●sin2 23 = 0.6, sin2 213 = 0.0067(sin223 ・ sin2213 is equal in the two cases.)
m2: positive, =3/4
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Sensitivity to octant of Sensitivity to octant of 2323
22
33
sin2 2
13
sin2223=0.96sin2223=0.99
Octant ambiguity of 23 can be resolved at 2 if sin2223 < ~0.97 (almost independent of the value of sin2213 and mass hierarchy).
Octant ambiguity of 23 can be resolved at 2 if sin2223 < ~0.97 (almost independent of the value of sin2213 and mass hierarchy).
Could resolve the 8 hold degeneracy of the oscillation parameters.
OA 2.5 degree for both Kamioka and KoreaOA 2.5 degree for both Kamioka and Korea
hep-ph/0609286
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Discussing T2KK more Discussing T2KK more
Sep.30 and Oct. 1Univ. of Tokyo
Your participation and contribution are most welcome!
http://www-rccn.icrr.u-tokyo.ac.jp/workshop/T2KK07/
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If non-zero 13 is observed….
• We hope to proceed to the next phase of experiment with higher power beam and larger detector(s).
• Goals: discovery of leptonic CP violation, and determination of mass hierarchy and octant of 23. (+ Various non-LBL physics).
• T2KK is one of the serious possibilities.• We will continue the studies.
If non-zero 13 is observed….
• We hope to proceed to the next phase of experiment with higher power beam and larger detector(s).
• Goals: discovery of leptonic CP violation, and determination of mass hierarchy and octant of 23. (+ Various non-LBL physics).
• T2KK is one of the serious possibilities.• We will continue the studies.
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End