Supported by Grant-in-Aid for Scientific Research (C) 24540295 andGrant-in-Aid for Scientific Research on Innovative Areas 24104501

ジルコニウム９６を用いたニュートリノを放出しない２重ベータ崩壊事象の探索実験ＩＩ
日本物理学会 第６８回年次大会
２０１３年３月２９日
福田善之、ナリンゲルラ、中川貴仁 (宮城教育大学)
森山茂栄(東京大学宇宙線研究所)
小川泉(福井大学工学部)

Neutrinoless double beta decay[T1/20ν(0+ ->0+)]-1 =G0ν(E0,Z)|M0ν|2<mν>2
T1/2~a(Mt/∆EB) a: abundance M: masst: meas.time ∆E: energy res. B: BG rate
Requirement : Low BG, Large target mass, High energy
resolution
２０１３年３月２９日

日本物理学会 第６８回年次大会

2Piquemal@ν2012

２０１３年３月２９日

日本物理学会 第６８回年次大会

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For future experiments

high energy
resolution
4%@2.5MeV

F.Piquemal@ν2012

http://kds.kek.jp/getFile.py/access?contribId=37&sessionId=16&resId=2&materialId=slides&confId=9151~tons of target will be needed for next generation detector
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Detector design for Zr in 100ton LS
Zirconium Complex in Organic liquid Scintillator(ZICOS)
Assuming 10w.t.% solubility
3m

10m
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Zirconium β-diketon complex
 Zirconium(IV) Advantage

acetylacetonate(Zr(acac)4)

 good solubility (over10w.t.%) in Anisole(PhOMe) Stable and cheep Commercial product Disadvantage
 Low scintillation light

Molecular weight : 487.66
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yield

日本物理学会 第６８回年次大会

6

Scontillation Light yield (60Co) withrespect to concentration of Zr(acac)4
concentrationof Zr(acac)4ObservedchannelExpectedchannel

0 mg

3850

3850

50mg
(1.03X10-4)

3175

3138

100mg
(2.05X10-4)

2800

2651

200mg
(4.10X10-4)

2000

2018

300mg
(6.15X10-4)

1600

1613

500mg
(1.03X10-3)

900

1178

PPO 100mg : 4.52X10-4 mol
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Improve scintillation light yield Move absorption peak

to shorter wavelength How to do it?

substituent groups
http://www.hi-ho.ne.jp/hosomi/sotsuron

Courtesy of Prof. Yoshiyuki Kowada(Hyogo University of Education)
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Absorbance peak for several
substituent groups

Measured absorbancepeaks for several
substituent groups

２０１３年３月２９日

Expected absorbancepeak for several
substituent groups

日本物理学会 第６８回年次大会

9

Zr β-diketon complex introducing
substituent groups (β-keto ester complex)
Zr(CH3COCHCOOCH(CH3))4 = Zr(iprac)4mw : 711.92

２０１３年３月２９日

Zr(CH3CCOCHCOO
CH3)4 = Zr(etac)4
mw : 665.81

日本物理学会 第６８回年次大会

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Zr β-keto ester complex
Zr(iprac)4+(iprac)1.5
state: powder

Zr(etac)4
state : dry solid

Synthesized by Prof. Takahiro Gunji (Tokyo University of Science)

Solubility > 10 w.t.% for anisole
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Absorbance spectra (Solvent effect)
Solution : Hexane

Solution : acetonitrile

solvent effectAbsorption peak moved to shorter wavelength
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Absorbance in another solvent
Solution : Diethyl Ether

Solvent effect could
depend on the polarity(dielectric const.)
 Acetonitrile : 37.5
 Hexane : 1.89
 Anisole : 4.3



Need solution which hassame polarity as anisole Diethyl ether : 4.33

Still absorption peakremains around 270nm
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Light yield of scintillation
Zr(iprac)5.5 in anisoleZr(etac)4 in anisoleSame quenting as Zr(acac)4 was observed
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Requirement of scintillator solvent

Low polarity (dielectricconst.)
 No absorption ~270nm

Aromatic compounds
 luminescence >270nm

Safety for human bodyand environment Usual solvent for L.S.
Toluene / Xylene
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Zirconium complex with luminescence Zr-ODZ complex

 Photo luminescencem.w. = 1040.18
Solvent : Acetonitrile
Concentration : 3.0×10-5 mol/L
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Emission and absorption of Zr(ODZ)4• Emission wavelength :430nm
PMT sensitive• Absorption wavelength:
270nm and 320nm
different from excitation W.L.

• Solvent : PhCN(Benzonitrile)• Solubility : ~5w.t.%
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Response for γ-irradiation
Most of emission light fromPhCN was not used for theemission of Zr(ODZ)4.
 Secondary excitation of~340nm was used for theemission of Zr(ODZ)4.
 Estimated Quantum yield
was obtained ~30% at firstexcitation of ~240nm.
Need another solvent
which has shorter emission
wavelength than PhCN.
２０１３年３月２９日

日本物理学会 第６８回年次大会

18Summary High solubility of Zr β-keto ester in Anisole(>~10w.t.%) for ZICOS detector was achieved.
 Confirmed absorption peak moves to shorter
wavelength (275nm → 245nm) by introducing
substituent groups.
 Observed scintillation light yield decreased inproportion to the concentration of Zr β-keto ester due
to remaining absorption @ 280nm.
Need lowpolarity solvent.
 Quantum yield of Zr(ODZ)4 was achieved ~30%, but
it was not used for scintillator due to no overlap
between emission of solvent and absorption of ODZ.
２０１３年３月２９日

日本物理学会 第６８回年次大会

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BACKUP

２０１３年３月２９日

日本物理学会 第６８回年次大会

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Neutrinoless double beta decay using
liquid scintillator


Experimental limits forneutrino mass

 Requirement for<mν>:50~100meV high energy
resolution
4%@2.5MeV low background rate
0.01count kg-1 y-1
 ton scale of target

Liq. Scintillator is easy to scale up target volume
２０１３年３月２９日

日本物理学会 第６８回年次大会

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What’s problem : Absorption spectra ofZr(acac)4 Emission peak ofanisole was observed
around 295nm.
 Absorption peak ofZr(acac)4 was observed
around 270nm.
Scintillation light from
PhOMe might beabsorbed by Zr(acac)4
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Simple expectation for quenting Assuming to same cross section

for light
Light yield = L0 ×
σ1Nppoσ1Nppo + σ2NZr
L0 : Light yield of anisole +PPO+POPOP
Nppo and NZr : No. ofmolecular for PPO and Zr(acac)4
σ1,σ2 : absorbance of PPO and Zr(acac)4
２０１３年３月２９日

日本物理学会 第６８回年次大会

23What’s problem
 Absorption spectra ofIn(acac)3 (indiumacetyl acetone) wasoverlapped with theemission spectra from
Anisole （Chem. Phys.
Lett., 435(2007), 252)
Same overlap of the emission and theabsorption spectrum would be occurred
even if different metal (Zr) was used.
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Scintillation light yield (137Cs) withrespect to concentration of Zr(acac)4

２０１３年３月２９日

concentrationof Zr(acac)4ObservedchannelExpectedchannel

0 mg

2450

2450

50mg

1800

1997

100mg

1400

1687

200mg

950

1284

300mg

650

1038500mg

300750

日本物理学会 第６８回年次大会

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Photo Luminescence and absorption of PPOPhoto luminescence Fluorescence device: HORIBA

FluoroMax-4
 Absorbance device : HITACHI
U-3000 Solvent : Benzonitrile (PhCN) Concentration : 1.0×10-5 mol/L 2,5-Diphenyloxazole
 Molecular mass : 221.26
 Max. emission wavelength :368.0nm Max. absorption wavelength :309.7nm
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Photo Luminescence and absorption ofPOPOP

Photo luminescence Fluorescence device: HORIBA

FluoroMax-4
 Absorbance device : HITACHI
U-3000 Solvent : Benzonitrile (PhCN) Concentration : 1.0×10-5 mol/L 1,4-Bis(5-phenyloxazol-2-yl)benzene
 Molecular mass : 364.40
 Max. emission wavelength :423.6nm
 Max. absorption wavelength :364.1nm
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Photo Luminescence and absorption of bisMSBPhoto luminescence Fluorescence device: HORIBA

FluoroMax-4
 Absorbance device : HITACHI
U-3000 Solvent : Benzonitrile (PhCN) Concentration : 1.0×10-5 mol/L 1,4-Bis(2-methylstyryl)benzene
 Molecular mass : 310.44
 Max. emission wavelength :426.6nm
 Max. absorption wavelength :355.3nm
２０１３年３月２９日

日本物理学会 第６８回年次大会

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Response for γ−ray for tetrakis 8quinolinolate Zr complex loaded scintillator
Tetrakis (8-quinolinolate)
Zirconium complex (ZrQ4)

ZrQ4 50mg in PhCN-POPOP
Quantum
Yield=1.1%
obtained by
optical method

NMn+O-n

M = In, n = 3; M = Zr, n = 4

Light Yield toBC505:=7.3%

ZrQ4 m.w. = 689.07
２０１３年３月２９日

日本物理学会 第６８回年次大会

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