口頭発表 @ 基研研究会 ppp2013 2013.08.08
TRANSCRIPT
次世代原子炉ニュートリノ実験の質量階層性への Sensi'vity
Yoshitaro Takaesu KIAS/KNRC
In collabora'on with S.F. Ge, N. Okamura and K. Hagiwara JHEP 1305:131,2013
Introduc'on
Mass Hierarchy
m1
m2
m3
Normal Hierarchy (NH)
m3
m1
m2
Inverted Hierarchy (IH)
�m221
|�m231|
� 2.3� 10�3eV2
� 7.5� 10�5eV2
�m221
|�m231|
m�
3 netrinos flavors �m221 = m2
2 �m21 � 7.5� 10�5
�m221 < |�m2
31| � 2.3� 10�3
PMT
Reactor neutrino experiment
�e
Reactor Detector
Inside Detector
Evis��
�
�
Inverse Beta Decay (IBD)
2� 1020 neutrinos/GW/sec
L
Energy distribu'on �e
@ detector �e
near
dNfar
dEvis=
NpT
4�L2
� �
Ethr
dE� �(E� )Pee �IBD G(E� , Evis)
Pee
far
L
Neutrino oscilla;on
How to dis'nguish Mass Hierarchy?
Detect the sign of (�m232)�m2
31
m1
m2
m3
m3
m1
m2
NH IH
The informa'on of mass^2 difference are in Oscilla'on Probabili'es.
MH difference in spectrum
10000 20000 30000 40000
30 km NH IH
2000 6000
10000 14000 40 km NH
IH
1000 3000 5000 7000
dN /
dEi [
1/M
eV]
50 km NH IH
0 1000 2000 3000 4000
2 3 4 5 6 7 8
Ei [MeV]
60 km NH IH
�e
Sensi'vity
analysis �2
The theore;cal predic;on is fiBed to the Data, assuming NH or IH.
�2min(NH) �2
min(IH)
Nfiti =
�dEvis
NpT
4�L2
� �
Ethr
dE� �(E�)Pee �IBD G(E� , Evis)
FiFng parameters are �12, �13, �m221, |�m2
31|, fsys
Penalty term
Nfiti
0
2
4
6
8
10
12
14
16
18
20
22
24
10 20 30 40 50 60 70 80 90 100
(6r2 ) m
in
L [km]
a = 2% NH3% NH4% NH5% NH6% NH
Sensi'vity to the Mass hierarchy
16.5GW 10kton 5yrs
Current value
NH
a � 7%
�EE
=
��a�E
�2
+ b2
�(�m231)
Effects of to the sensi'vity
|�m231|
L = 30km
�|�m231|
|�m231|
L = 50km
Baseline should be long enough
|�m231|+��2 fit
�2 fit |�m231|+�
0
2
4
6
8
10
12
14
16
18
20
22
24
10 20 30 40 50 60 70 80 90 100
(6r2 ) m
in
L [km]
a = 2% NH3% NH4% NH5% NH6% NH
Sensi'vity to the Mass hierarchy
16.5GW 10kton 5yrs
Current value
NH
a � 7%
�E
E=
a�E
Effect of Energy Resolu'on
a = 0 a = 6%
Evergy Resolu'on affects the sensi'vity significantly.
�E �= 0
�E
E=
a�E
Expected Energy Resolution
PMT coverage : 67% (15,000 20” PMTs)
PMT coverage : 67% (15,000 20” PMTs)
+ Attenuation length : 25 m
+ QE : 35%
J.S. Park, S.B. Kim
Effect of Energy Resolu'on 2
16.5GW 10kton 5yrs
�EE
=
��a�E
�2
+ b2
• Sensi'vity is reduced by ~ 40% • Op'mized L is shortened by ~ 5 km
b = 0% b = 1%
a = 2% a = 3%
0
1
2
3
4
5
6
7
8
10 20 30 40 50 60 70 80 90 100
(6r2 ) m
in
L [km]
(a, b) = (3, 0) NH(3, 0.5) NH
(3, 0.75) NH(3, 1) NH
0
2
4
6
8
10
12
14
16
18
20
22
24
10 20 30 40 50 60 70 80 90 100
(6r2 ) m
in
L [km]
(a, b) = (2, 0) NH(2, 0.5) NH
(2, 0.75) NH(2, 1) NH
Other Limicng Factors
Mul'-‐reactor interference
L1 L2
E. Ciuffoli, J. Evslin, X. Zhang: 1302.0624 Y-‐F. Li, J. Cao, Y. Wang, L. Zhan: 1303.6733
Baseline difference should be small.
ΔL = L1 – L2
Mul'-‐reactor interference
Other reactor sites influence the sensi'vity.
All Reactors
16.5GW 10kton 5yrs a = 3%, b = 0.5%
�EE
=
��a�E
�2
+ b2
YongGwang only
01234567891011
(��2)min
Mul'-‐reactor interference All Reactors
01234567891011
(��2)min
16.5GW 10kton 5yrs a = 3%, b = 0.5%
�EE
=
��a�E
�2
+ b2
RENO site
In latest RENO-‐50 proposeal: Site changed 18 kton detector
Energy scale uncertainty Energy scale uncertainty is controlled ~ 1% for RENO detector.
J. Evslin et.al. arXiv: 1308.0591
No E scale Unc. Unknown E scale (worst case)
Effect of E scale Uncertainty
Schedule for MH determina'on 2010 2030 2020
RENO-‐50
DayaBay II
LBNE
LBNO
PINGU
INO
NOvA (Opera;ng)
(Approved)
Hyper K
2015 2025
* rough es;mate 2 sigma 3 sigma 4 sigma 5 sigma
Summary RENO50-‐like Experiment for MH determina=on.
With 16.5GW 18kton,
a < 3% b < 0.5%
of Energy Resolu=on is required > 2 ~ 3-‐sigma determina;on within 5 years.
�EE
=
��a�E
�2
+ b2
Interference among reactor cores significantly affects the sensi;vity.
Energy Scale uncertainty should be controlled very Carefully.
Many Efforts for MH determina;on have started !