2005/12/02-04 NNR05 N. Ishihara 1

DCBADCBA and 150Nd matrix elementsN. Ishihara (KEK)

ContentsContents1.1. Introduction to DCBAIntroduction to DCBA2.2. Present statusPresent status3.3. Future projectFuture project4.4. 150150

Nd source plateNd source plate5.5. SummarySummary

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VTXβ1

β2

X

Y VTX

β2

β1

Z

Y

β1

VTX

β2

X

Z

B

Y

XZ

ee mmpT

rBp

−+=

=2/122 )(

,3.0cosλ

p (MeV/c): momentum, r (cm): radius, λ: pitch angle

B (kG): mag. field, me (MeV/c2): electron mass210 mm

240

mm

DCBADrift Chamber

Beta-ray Analyzer

150Nd→150Sm+2e-

Test Module

Test Module

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,cos

3.0λ

RBp =

( ) ,tan 2222

λσσσσλ+

+

=

BRp

BRp

( )

( )( ) ,8

2112

Empirical,cos16

cos5720

0

2

2

22

0

2

24

22

XL

pLNNN

XL

LpLNR

+

++≈

+

+≈

βδ

σ

λβλε

σ

λ

,

=

pTp

TpT

σβσ T: kinetic energy (MeV), p: momentum (MeV/c)B: magnetic field (kG), R: helical radius (cm)λ: pitch angle, L: track length (cm)X0: radiation length (cm), ε: res. in X-Y plane (cm)δ: res. in 3d space (cm)

Energy Resolution

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Simulation study on energy resolution for 150Nd (Q=3.37 MeV)

Energy resolutionFWHM=0.2 MeV(6% at Q-value)

Geant4

Preliminary

σX = 0.5 mm

σY = 0.5 mm

σZ = 0.5 mm

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PICKUPWIRE

ANODEWIRE

SOURCE PLATES

CATHODEWIRE

F A D C

FA

DC

3

3

3

50

B

e-

ANODE PICKUP

TEST CHAMBER FOR POSITION RESOLUTION

Gas: He (90%) + CO2(10%)

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Cosmic-ray (Straight track)

Y

X

X

Z

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Position Resolutions Obtained From Cosmic-ray Events

Required position resolution has been almost achieved.

Energy resolution is under study using conversion electrons from 207Bi.

σY = 0.14 mm

σZ = 0.41 mm

σX = 0.61 mm

Preliminary

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Electron Tracks of Test Chamber

Internal Conversion Electronfrom 207Bi (0.5 MeV) Electron Track (0.1 MeV)

Y

X

Y

X

Z

X

Z

X

B = 0.6 kG B=0.8 kG

•

•

•

•

Emission Point

E. P.

E. P.

E. P.

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DCBA-T2 in 0.8 kG

SIDE VIEW

TOP VIEW

540

Pickup

CathodeFRONT VIEW

36044

0

AnodeSourcePlate

SourcePlate

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DCBA-T

Comparison of DCBA-T2 and TEST CHAMBER

TEST CHAMBER

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DCBA-FutureSource plate: 84 m2/moduleThickness: 15 (40) mg/cm2

Weight: 12.6 (33) kg/module10 module → 126 (330) kg

DCBA-F moduleWeight ~ 10 t

Anode wire: 10720/modulePickup wire: 13160/module

yearNd/module.90% for eV1.0

yearNd/module. naturalfor eV3.0150>≈<

>≈<

ν

ν

m

m

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Configuration of DCBA-F Module

Source PlatesCalculated (σT/T) ≈ 3% for 1 MeV electron of λ=0

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Nuclear Structure Factor and Q-valueF.T. Avignone III, Nucl. Phys. B (Proc. Suppl.) 143 (2005) 233.

336757.0150Nd24790.28136Xe25334.2130Te28021.3116Cd30345.0100Mo29951.7082Se20390.7376Ge42710.5448Ca

QkeV

η= <FN>×1013 y-1

<FN>= <G0ν|M0ν|2> y-1

Isotope

140.34.1 10)4.5( −+

− ×1410)6.03.7( −×±

134.03.0 10)7.1( −+

− ×1310)15.00.5( −×±

137.03.0 10)3.1( −+

− ×1310)5.02.4( −×±

1410)4.08.2( −×±120.1

7.0 10)7.5( −+− ×

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Estimated half-lives and decay rate corresponding to <mν>=0.04 eV

2.4×10-26

1.2×10-28

1.8×10-27

5.3×10-28

2.1×10-27

7.4×10-28

3.0×10-28

2.3×10-28

2.9×1025150Nd5.8×1027136Xe3.9×1026130Te1.3×1027116Cd3.3×1026100Mo9.4×102682Se2.3×102776Ge3.0×102748Ca

Isotope y02/1νT 1−yββλ

F.T. Avignone III, Nucl. Phys. B (Proc. Suppl.) 143 (2005) 233.

( ) 2

2

210

2/1 MGmm

Te

><=

− νν

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Allowed Background Rate

resolutionEnergy : weight,Source:

rate background normalized:

ratebackground:9

rateevent:32

dEMEM

bB

nb

bn

δ>=<

=

=

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Comparison of Isotope in Detectors

0.81.1×10-60.073302000.55.657.0DCBA (150Nd)10.92×10-413.23302000.58057.0DCBA (150Nd)

0.052×10-4 (*)3×10-472500.57955.0NEMO3 (100Mo)

0.66×10-70.043302000.5901.7DCBA (82Se)

0.8

1.9

4.20.3

n(y-1)

3.8×10-50.075003.70.75860.73Majorana (76Ge)

6×10-60.43302000.5905.0DCBA (100Mo)

7.8×10-52 1262000.58057.0DCBA (150Nd) 4×10-70.011262000.55.657.0DCBA (150Nd)

<B>(keV-1kg-1y-1)

b(y-1)

M(kg)

δE(FWHM)

(keV)

εa(%)

ηDetector

(*) Experimental value

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Summary1. DCBA is a momentum analyzer with a magnetic field. Three

dimensional track-reconstruction of charged particle provides a lot of information such as kinetic energy, charge identificationand decay vertex. The information is a powerful tool for eliminating background.

2. Energy resolution is the most important item in R&D of DCBA. Test apparatus DCBA-T2 is under construction in order to study the energy resolution using conversion electrons from 207Bi.

3. Decay Isotope of 150Nd is expected to have large nuclear matrix element. Enrichment of 150Nd is really desired to be 80-90% instead of 5.6% natural abundance.

4. If 80-90% 150Nd is available to DCBA, the future project is expected to search for neutrino mass down to 0.04 eV.