MOONMOON forfor next-generation neutrino-next-generation neutrino-less double beta decay experiment ;less double beta decay experiment ;
present status and perspectivepresent status and perspective
Outline of the MOON detector Background rejection & Expected sensitivity R&D Summary
T. ShimaResearch Center for Nuclear Physics, Osaka University
for the MOON collaboration
TAUP2007, Sendai, September 11-15, 2007
MOON collaboration MOON collaboration H. Ejiri* (CTU-Praha, RCNP/Osaka and NIRS) T. Itahashi, K. Matsuoka, M. Nomachi, S. Umehara (Phys./OULNS, Osaka Univ.) T. Shima (RCNP, Osaka Univ.) K. Fushimi, K. Yasuda, Y. Kameda (GAS, Univ. of Tokushima) R. Hazama (Hiroshima Univ.) H. Nakamura (NIRS) S. Yoshida (Tohoku Univ.) T. Kii (IAE, Kyoto Univ.) P.J. Doe, R.G.H. Robertson*, D.E. Vilches, J.F. Wilkerson, D.I. Will (CENPA, Univ. Washington) S.R. Elliott, V. Gehman (LANL) J. Engel (Phys. Astronomy, Univ. North Carolina) M. Finger, M. Finger, K. Kuroda, M. Slunecka , V. Vrba (Phys. Charles Univ. and CTU-Praha) M. Greenfield (ICU, Tokyo) A. Para (FNAL) A. Sissakian, V. Kekelidze, V. Voronon, G. Shirkov, A. Titov (JINR) V. Vatulin, P. Kavitov (VNIIEF)
* Contact persons.
Goal of next-generation DBD experimentsGoal of next-generation DBD experiments
QD: 100~200 meV
NEMO3 CUORITINO
IH: 50~25 meV
Next-generation: Super-NEMO, MOON
NH: 4~2 meV
Future experiment
KKDC 440meV
132 Thermal Leptogenesis scenario favors 1meV < m < 0.1eV
Astronomical observations (PLANCK, Ly-a, weak lensing etc.) will provide constraints of 25~65meV on m.
00 nuclear matrix nuclear matrix elementelement
222
00002/1
00 /2log emmMGtNT
tNY
Isotope Q [MeV] G0 [10-14 yr-1] M0 G0·|M0|2
76Ge 2.039 0.44 2.80-4.33 3.45-8.25
82Se 2.992 1.89 2.53-3.98 12-30
96Zr 3.351 3.95 1.49-3.55 8.8-49.8
100Mo 3.034 3.17 0.77-4.67 1.9-69
116Cd 2.804 3.24 1.09-3.75 3.85-45.6
128Te 0.876 0.12 2.17-4.58 0.57-2.52
130Te 2.529 2.86 1.80-3.59 9.3-36.9
136Xe 2.467 3.03 0.66-4.64 1.3-65
150Nd 3.368 13.4 3.33-4.51 149-273
MOON MOON Mo/Majorana Observatory Of NeutrinoMo/Majorana Observatory Of Neutrino
1 unit = 42 modules = 20kg source
10~30mm
15mm
20~40mg/cm2
DetectorsDetectors
Plastic scintillators (2m×1m×15mm/layer) : -ray energy & time, -ray veto FWHM E/(E1+E2) = 7%@3MeV → 5%
Wire chambers (2m×1m×10~30mm/layer) : gas mixture; Ar+CO2 particle ID; / correction for position dependent response of PLs delayed anti-coincidence with , position separation of 5mm×5mm (wire-spacing + charge-division or anode×cathode)
Active shieldings : thick PL or NaI
FeatureFeaturess
Compact and modular structure
scalable from sub-tons to multi-tons easy to shield against external & internal BG’s large acceptance
Multi-layers of source foils, scintillators and wire chambers
capability to measure different nuclei sensitivity to energy- and angular- correlations good selectivity of and BG with information of E, t, position
Real-time detection of low-energy solar Real-time detection of low-energy solar
pp
7Be
pep
8B
BackgroundsBackgrounds
RI impurities with large Q : 214Bi, 208Tl
(n,n’), (n,) by -induced neutrons
2 : 2/0 > ~1/105
208208Tl (QTl (Q=4.999MeV) : =4.999MeV) : ---- in source foil in source foil
anti-coincidence by 1
coincidence with MWPCs on both sides of source
--- to be rejected with
Response for 1.8MeV Response for 1.8MeV +583keV +583keV +2614keV +2614keV
Gate conditionCounts in
2.9-3.2 MeV[ /ton/yr]
E1+E2 > 0keV 5280
E1, E2 > 500keV 2640
Veto by other PL 9
MWPCs on both sides coincidence
0.32
Track consistency 0.28
20mBq/ton 208Tl in 100Mo
~0.3 events for 1 ton·yr measurement
E1+E2 [keV]
Co
un
ts
(a) E1+E2>0keV(b) E1, E2 > 500keV(c): (b) & PL-veto(d): (c) & MWPC coin.(e): (d) & position
208Tl 1.8MeV + 2.6MeV + 0.58MeV 1.81E+7 decays
0 1000 2000 3000 4000 5000
100
101
102
103
Neutron-induced Neutron-induced -rays-rays
Main components of MOON detector; 12C, 1H, 100Mo, etc.
Quantity [mole/unit]
(inelastic)(average) [b]
(capture)(thermal) [b]
12C 1.1×105 0.4 0.0034
1H 2.2×105 0 0.332
100Mo 200 0.9 0.282Se 244 0.8 0.799
150Nd 133 1.25 15.9
1H(n,)2H ; Q=2.225MeV << Q of 100Mo, 82Se, 150Nd…
Production rates of neutron-Production rates of neutron-induced induced
Reaction R [unit-1 s-1]12C inelastic (4.44MeV) 2.1×10-6
100Mo inelastic 3.3×10-8
12C thermal capture 1.9×10-8
100Mo thermal capture 5.5×10-9
Total 2.2×10-6
n (En < 20MeV) ~10-8 n/cm2/MeV/s at 2000m w.e. (Gaitskell 2001)
Response for 5MeV Response for 5MeV
Energy [keV]
Cou
nt /
-ra
y [k
eV-1
]totalE1, E2>500keVPL-vetoMWPC-coin.
0 1000 2000 3000 4000 500010-9
10-8
10-7
10-6
10-5
10-4
10-3
0 window
~0.2 events for 1 ton·yr measurement at 2000m w.e.
Estimated background rates ; Estimated background rates ; summarysummary
Background source Rate [/ton/yr]
208Tl -- in source <~0.6
214Bi - in source ~0.1
214Bi (1- → 0+ ) <0.01
Two external 2614keV s
acc. coin. (for 0.1Bq/kg 232Th)~0.03
Neutron-induced 0.2~1
100Mo 2 (FWHM=5%) 4.1
Total ~6
Sensitivity for <mSensitivity for <m> ; > ; 100100Mo 0Mo 0
Nt [tonyr]
<m
> (
90%
C.L
.) [m
eV]
100Mo 30mg/cm2 M0=3.93
FWHM:3%4%5%7%
10-3 10-2 10-1 100 101 102
101
102
103
Sensitivity vs. Energy resolutionSensitivity vs. Energy resolution
MOON-1
MOON-1 (correct for position)
FWHM at 3MeV [%]
<m
> s
ensi
tivity
(90
%C
.L.)
f
or 1
t x
1yr
exp.
[m
eV]
82Se100Mo
NME---Kortelainen & Suhonen (2007)
0 1 2 3 4 5 6 7 8
20
40
60
80
100
120
MOON-1MOON-1 6-layers of PL 53×53×1cm3, Mo-Foil 142g @20mg/cm2×2
H. Ejiri, Czeck. J. Physics, 56 (2006) No 5, 459.
H. Nakamura, et al., nucl-ex/0609008
E/E(FWHM) = 7% at 3MeV
→ 5% with correction for position dependence
Energy [keV]
E/E
in F
WH
M (
%)
Conversion e-
Compton e-
137Cs662keV
207Bi976keV
22Na1271keV
40K1461keV
208Tl 2614keV
0 500 1000 1500 2000 2500 3000
5
10
15
20
PLs Mo foils PMTs
R&D; prototype NaI(Tl) scintillatorR&D; prototype NaI(Tl) scintillator
provided by Horiba, Ltd.
150mm×150mm×10mm slab, three PMTs on each side
better energy resolution for and BG s
sensitivity for to excited states
SummarySummary
MOON is one of the feasible solutions for next-generation 0experiment, because of its high efficiency, good resolutions (E, x, t), compactness, scalarbility, etc.
- Road map -
Phase
N [t] ×T [y] T1/2 1026 [y] <m> [meV]
82Se 100Mo
I 0.03 × 4 0.9 113 105 122 107
II 0.12 × 4 3.5 66 59 76 66
III 0.48 × 4 10.1 40 34 49 41
FWHM= 5% or 4% @3MeV
Cf. Next-generation 76Ge experiments ; 1ton×4yr ~40meV⇒
214214Bi (QBi (Q=3.27MeV) : single =3.27MeV) : single
energy losses in both PLs > 500keV -ray track positions in MWPCs (5mm×5mm)
--- rejected with
Response for Response for 214214Bi single Bi single
Gate conditionCounts in
0 window[ /ton/yr]
E1+E2 > 0keV 713
E1, E2 > 500keV 0.91
Veto by other PL 0.83
MWPC coin. 0.002
Track consistency 0.002
20mBq/ton 214Bi in 100Mo
~0.002 events for 1 ton·yr measurementE1+E2 [keV]
Co
un
ts
(a) E1+E2 > 0keV(b) E1, E2 > 500keV(c): (b) & PL-veto(d): (c) & MWPC coin.(e): (d) & position
214Bi 1- 214Po 0+ g.s. (18%): 5.83E+7 decays
2800 3000 3200 3400
100
101
102
103
214214Bi (QBi (Q=3.27MeV) : =3.27MeV) : --
anti-coincidence by Compton-scattered coincidence with MWPCs on both sides of source
--- rejected with
Response for Response for 214214Bi Bi --
Gate conditionCounts in
0 window[ /ton/yr]
E1+E2 > 0keV 44
E1, E2 > 500keV 23
Veto by other PL 9
MWPCs on both
sides coincidence0.09
Track consistency 0.09
20mBq/ton 214Bi in 100Mo
~0.1 events for 1 ton·yr measurement
E1+E2 [keV]
Co
un
ts
(a) E1+E2>0keV(b) E1, E2 > 500keV(c): (b) & PL-veto(d): (c) & MWPC coin.(e): (d) & position
214Bi 1.5MeV + 1.76MeV 2.2E+6 decays
0 1000 2000 3000
100
101
102
103
-induced neutrons-induced neutrons
Energy spectrum: n (En < 20MeV) ~10-8 n/cm2/MeV/s
1212C+n cross sectionsC+n cross sections
Neutron Energy [MeV]
Cro
ss S
ecti
on
[b
] total
(n,n)
(n,)
(n,p)
0 5 10 15 2010-3
10-2
10-1
100
101
Inelastic Inelastic
n [n/s] n,n’> [b] N [atoms/b] R [s-1]
12C 2.8×10-6 (4.4~20MeV)
0.4 1.86 2.1×10-6
100Mo 3.6×10-6 (<20MeV)
0.9 0.01 3.3×10-8
( for one unit (42 modules, 20kg 100Mo) )
Capture Capture
n
HMoC
i
NNN
NiR
110012
)(
( i = 12C, 100Mo, or 1H )
Assuming all neutrons are thermalized and captured inside the detector….
][s
][s 1-
-1
9100
812
105.5)(
109.1)(
MoR
CR
374 73000 [b·mole/unit]40
Accidental Coincidence of external 2614keV -rays
Response for 2614keV single -ray (0.1Bq/kg 232Th in PMTs)
Gate condition Suppression
Total 1
E>500keV 0.47
Veto with other PLs 0.035
MWPC coin. 6.3e-4
Single track 5.3e-4
Energy [keV]
Cou
nts
[/ke
V/to
n/yr
]
TotalE>500keVPL-vetoMWPC-coin.Single track
1000 2000 3000106
107
108
109
1010
1011
Coincidence rate
Number of PMT (/unit) 4300
Mass of PMT (kg/unit) 3010
Gamma Rate (/s/unit) ; 100mBq/kg
301
Count Rate (/s/unit) ; =1.6 120.4
Count Rate (/yr/unit) 3.80E+09
Single Track (ratio) 0.022
Single Track (/yr/unit) 8.31E+07
Coincidence (ratio) 0.11
Coincidence Time (sec) 1.00E-05
Vertex (ratio) 2.54E-06
Coincidence Rate (/yr/unit) 6.07E-04
Coincidence Rate (/yr/ton) 3.03E-02