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