Presentation @ KIAS pheno group end year meeting: 2012.12.20

1. Reactor
neutrino
experiment
1
e
Flux
@
Reactor
Pee
@
far
detector
e
e + p e+
+ n
Mass
Hierarchy
determina;on
with
E Evis + 0.8MeV

2. Oscilla;on
2
Mass
Hierarchy
difference
e e

3. Energy
distribu;on
@
far
detector
3
10000
20000
30000
40000
30 km NH
IH
2000
6000
10000
14000 40 km NH
IH
1000
3000
5000
7000
dN/dE[1/MeV]
50 km NH
IH
0
1000
2000
3000
4000
2 3 4 5 6 7 8
E [MeV]
60 km NH
IH
e

4. Obstacle1:
4
@
<
30
km,
the
NH-­‐IH
difference
is
totally
absorbed
by
a
small
shiM
of
within
its
uncertainty.
We
need
a
far
detector
at
L
>
30
km
| m2
31|
| m2
31|

5. Obstacle2:
finite
Energy
Resolu;on
5
b: systematic error part
a: statistical error part
AMer
smearing
with
the
detector
Energy
resolu;on,
the
NH-­‐IH
difference
Can
be
absorbed
again.
E
E
=
a
E/MeV
2
+ b2
Upper
limit
on
the
Energy
Resolu;on

6. Sensi;vity
for
mass
hierarchy
6
0
2
4
6
8
10
12
14
10 20 30 40 50 60 70 80 90 100
(2
)min
L [km]
b = 0
a = 2% NH
IH
3% NH
IH
4% NH
IH
5% NH
IH
6% NH
IH
20
GW
5kton
5
years
a
<
3%
for
E
E
=
a
E/MeV
2
+ b2
Op;mal
L
~
50
km
( 2
)min > 9

7. Systema;c
Error
of
Resolu;on
7
0
2
4
6
8
10
12
14
10 20 30 40 50 60 70 80 90 100
(
2
)min
L [km]
(a, b) = (2, 0) NH
IH
(2, 0.5) NH
IH
(2, 0.75) NH
IH
(2, 1) NH
IH
E
E
=
a
E/MeV
2
+ b2
b
<
1%
for
20GW
5kton
5
years
Larger
b
Shorter
op;mal
L
( 2
)min > 9

8. 8
0.7
0.75
0.8
0.85
0.9
0.95
1
0 10 20 30 40 50
C.L.
( 2
)min
×1
×2
×3 ×4
×1
×2
×3
×4
×6
×8 ×10
L = 50 km
(a, b) = (2, 0.5): NH
IH
(3, 0.75): NH
IH
No Fluctuation
Considering
fluctua;on
of
data
20GW
5kton
5
years
n

9. Parameter
measurement
9
0.5
1.0
1.5
2.0
sin2
2 12
×10
-2
(a, b) = (3, 0.5) NH
IH
(3, 1) NH
IH
(6, 1) NH
IH
1
2
3
4 sin
2
2 13
×10
-3
0.5
1.0
1.5
StatisticalUncertainty
m2
21
×10-6
eV2
0
2
4
6
10 20 30 40 50 60 70 80 90 100
L [km]
| m
2
31|
×10
-5
eV
2
Parameter
measurements
are
not
sensi;ve
to
the
Energy
resolu;on
~
0.5%
level
of
uncertain;es
can
be
achieved
for
sin2
2 12
| m2
31|
m2
21

10. OutLook
• Consider
the
energy
scale
uncertainty
of
the
detector
• Find
a
suitable
place
in
Korea,
taking
into
account
mul;-­‐reactor
interference
• MH
determina;on
with
Long
baseline
neutrino
oscilla;on,
i.e.,
T2KK
10

11. Other
On-­‐going
Projects
• QCD
Mul;-­‐jet
genera;on
with
MadGraph
– pp
>
5
jets
becomes
possible,
but
not
6
jets
– Now
improving
phase
space
integra;on
(MadEvent)
• gg
>
4g
is
checked
with
new
integra;on
method
• gg
>
5
g
under
going
(want
to
go
up
to
gg
>
7g
)
• Implementa;on
of
spin-­‐3/2
par;cle
into
FeynRule/MadGraph,
FR/CalcHep
– Almost
done,
now
in
valida;on
phase
11

12. 12
Thank
you

13. Summary
• We
study
the
sensi;vity
of
a
future
medium
baseline
reactor
neutrino
experiment
for
MH
determina;on.
• For
20
GW
5kton
5
years
exposure,
–
op;mal
baseline
length
~
50
km
–
<
3%
sta;s;cal
&
<
1%
systema;c
errors
of
Energy
Resolu;on
is
required
–
0.5%
level
of
accuracy
for
Neutrino
Parameters
13
*
This
study
gives
the
minimum
requirement
for
the
energy
resolu;on.
*
More
realis;c
study
is
very
sensi;ve
to
the
environment,
such
as
distribu;on
of
reactors
within
~100
km
from
the
far
detector
(J.Evslin
et.al,
arXiv:1209.2227).

14. 14
-0.25
0
0.25
0.5 sin
2
2 12
2% NH
IH
3% NH
IH
6% NH
IH
-0.25
0
0.25
0.5 sin
2
2 13
-0.25
0
0.25
0.5
pullfactor
m
2
21
-0.25
0
0.25
0.5
| m
2
31|
-0.25
0
0.25
0.5
10 20 30 40 50 60 70 80 90 100
L [km]
fsys

15. 15
-10 0 10 20 30
50
100
150
( 2
)min
E
E
=
2%
E/MeV
2
+ (0.5%)2
L = 50km
1000 experiments
( 2)min = 11.2
( 2
)min = 7.1

16. 16
-5
0
5
10
15
20
10 20 30 40 50 60 70 80 90 100
(2
)min
L [km]
20GWth, 5kton (12.00% proton), 5 years, ( Evis/Evis)2
= ( (a / Evis)2
+ b2
)%
(a, b) = (2, 0.5) NH
IH

17. Determina0on
of
mass
hierarchy
with
reactor
neutrino
experiment
Yoshitaro
Takaesu
KIAS/KNRC
17
In
collabora0on
with
S.F.
Ge,
N.
Okamura
and
K.
Hagiwara

18. Introduc;on
• DayaBay
and
RENO
observed
large
• There
is
a
possibility
that
neutrino
mass
hierarchy
is
determined
by
observing
reactor
neutrino
oscilla;on
at
km
away
• In
this
talk,
I
discuss
the
sensi;vity
of
the
future
medium
baseline
reactor
experiments
for
determining
mass
hierarchy
18
13
O(10)

19. Mass
Hierarchy
19
If
we
assume
there
are
3
types
of
netrinos,
there
are
6
possible
mass
hierarchies.
We
know
There
are
two
possibili;es
leM,
NH
and
IH.
Which
one
is
realized
in
Nature?
Long
standing
and
big
ISSUE.
m2
21 = m2
2 m2
1 7.5 10 5
m2
21 < | m2
31| 2.3 10 3
m1
m2
m3
m1
m2
m3
Normal
Hierarchy
(NH)
Inverted
Hierarchy
(IH)
| m2
31|
m2
21

20. We
es;mate
– Op;mal
baseline
length
– Energy
resolu;on
required
– Expected
uncertain;es
of
neutrino
parameters
Assuming
an
experiment
with
20
GW
5kton
(12%
free
proton)
5
years
exposure.
20

21. Analysis
method
21
We
calculate
the
neutrino
energy
distribu;on
for
NH
or
IH,
Energy
Resolu;on
smearing
(Gaussian)
We
then
perform
the
standard
analysis
to
this
“data”
(next
slide).
dNNH(IH)
dEobs
=
NpT
4 L2
dE
dN
dE
Pee(L, E ) IBD(E )G(Etrue
Eobs
, E)
*
corresponds
to
the
averaged
observed
distribu;on.
We
don’t
consider
the
fluctua;on
of
data
from
experiment
to
experiment
in
this
talk.
dNNH(IH)
dEobs
We
introduce
bining
and
prepare
“data”,
the
number
of
events
in
each
bin.
N
NH(IH)
i =
Eobs
i+1
Eobs
i
dEobs dNNH(IH)
dEobs (i = 1, · · · , nbins)
2

22. Analysis
method
-­‐
22
The
sensi;vity
to
determine
MH:
2
Analysis

23. Results
23