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Yoshitaro TakaesuU. of Tokyo
The possibility of determining neutrino properties with Korea related neutrino
experiments.
Introduction
2
opened the window to access the neutrino mass hierarchy (MH)and lepton Dirac CP phase
Reactor
JUNO (DayaBay2)
RENO-50
Mass Hierarchy
3
P (νe → νe) =
3
i = 1
Uei exp − im2
i
2E i
U∗ei
2
= P (νe → νe)
∆ i j =∆m2
i j L
4Eν
Reactor neutrino experiment
νe
Detector
Reactors
6 × 1023 νe/ 3GW/ 15min
5
PMT
Inside Detector (Inverse Beta Decay)
MH difference in spectrumνe
6
δE
E=
a%√
E
dN
dE obsvis
=NpT
4πL 2
∞
E t h r
dEν φ(Eν ) Pee(Eν , L , MH, · · · ) σIBD (Eν ) G(Evis − E obsvis ,δEvis)
NHIH
Sensitivity to the Mass hierarchy
The typical sensitivity curve of this experiment
Small flux
8
Vvvv vvv
Effects of to the sensitivity
L = 30km
L = 50km
9
0%
2.5%
-2.5%
δ(|∆ m231|)
|∆ m231|
10 20 30 40 50 60 70 80 90 km
Sensitivity to the Mass hierarchy
The typical sensitivity curve of this experiment
Small flux
10
Vvvv vvv
Effect of Energy Resolution 2
δE
E=
a√
E
2
+ b2
18kton 16.5GW 5yrs
20 30 40 50 60 70 80 90 100
L [km]
b = 0%
0.5%
0.75%
1%
a = 3%a = 2%
b = 0 b = 1% Sensitivity 40%
Imrovement of b term is also important13
Current value
How to achieve better Energy Resolution?
Increase the photo-electron (p.e.)detected by PMT.
p.e.~ 200 pe/MeV ~ 2000 pe/MeV
Ex)
• Increase PMT coverage
• Increase QE of PMT
• More transparent LS
14
~ 6% ~ 2%
25m 35%
δE
E=
3.7%
E/ MeV
Energy Resolution (simulation)
J.S. Park (RENO)
δE
E=
4.4%
E/ MeV
δE
E=
4.4%
E/ MeV
E. Ciuffoli, J. Evslin, X. Zhang: 1302.0624Y-F. Li, J. Cao, Y. Wang, L. Zhan: 1303.6733
ΔL = L1 – L2
Reactor1
Multi-reactor interference
L1 L2
17
Reactor1 + Reactor2
multi-cores
Multi-reactor interference 16.5GW
18kton 5yrs
a = 3%, b = 0.5%δE
E=
a√
E
2
+ b2
(∆ χ2)min
All Reactors50 km
18
250m
Parameter measurement
< 0.5% accuracy
can be measured accurately @ L ~ 50 km
L = 50km
1%
1%
1%
1%
* Effect of energy scale unc. Is not considered.
Summary: Reactor neutrinoFuture Reactor neutrino Experiment for MH determination
For > 3-sigma determination within 5 years
a < 3%
b < 0.5%
of Energy Resolution is required
with 16.5GW 18kton Reactor Complex.
Interference among reactor cores significantly affects the sensitivity.
•Energy Scale uncertainty should be controlled very carefully.arXiv: 0901.2976, 1208.1551, 1308.0591
* Neutrino parameters can be determined with < 1% accuracy.
21