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Ⅳ
日本物理学会

第６９回年次大会

201４年３月2７日
宮城教育大学教育学部

小畑旭、ナリンゲルラ、福田東京大学宇宙線研究所
福井大学工学部

森山
小川

茂栄
泉善之

ZIRCONIUM COMPLEX IN ORGANIC LIQUIDSCINTILLATOR FOR DOUBLE BETA DECAY
EXPERIMENT (ZICOS EXPERIMENT)
Goals ：
(1) ≧ 10w.t.% solubility(2) 60% light yield to BC505(3) 4% @ 2.5MeV E-resolution

3mZirconium loaded 100ton LS(300kg 96Zr assuming10% enrich)
日本物理学会 第６９回年次大会

10mMar 27th, 2014

2

ZIRCONIUM ΒETA-KETO ESTER COMPLEX
Zr(CH3COCHCOOCH(CH3)2)4Zr(CH3COCHCOOCH2CH3)4 == Zr(iprac)4
mw : 663.87

Zr(etac)4mw : 607.76

Solubility > 10 w.t.% for anisole
日本物理学会 第６９回年次大会

Mar 27th, 20143

ABSORBANCE SPECTRA FOR ZIRCONIUM
BETA-KETO ESTER COMPLEX
Absorption peaks ofzirconium b-keto ester
complex were foundaround at 245nm,
however small bump
existed around 280nm.
Zr(CH3COCHCOCH3)4 =Zr(acac)4mw :487.66
日本物理学会 第６９回年次大会

Mar 27th, 2014

4ABSORBANCE SPECTRA FOR ZIRCONIUM
BETA-KETO ESTER COMPLEX AFTER 1 WEEKSmall bump disappeared
after ~ 1 week.
It could be explained byimpurities of Zr complex,
and they should be
precipitated on bottom ofthe vial.

(see explanation slide)
日本物理学会 第６９回年次大会

Mar 27th, 2014

5

LIGHT YIELD OF LS CONTAINING ZIRCONIUM
BETA-KETO ESTER COMPLEX
Light yield decreased
as increasing theconcentration of thecomplex.
~70%

Still exists small bumpof absorption around
280nm in anisole ?
~36%

日本物理学会 第６９回年次大会

Mar 27th, 20146

ABSORBANCE SPECTRA FOR ZIRCONIUM
BETA-KETO ESTER COMPLEX IN ANISOLE
Small bump around
280nm in anisole did notdisappear even after ~ 1week.
Impurities might bedissolved in anisole…
We have to purify thecomplex by using suchas sublimation.
日本物理学会 第６９回年次大会

Mar 27th, 20147

ABSORBANCE SPECTRA FOR ZIRCONIUM
BETA-KETO ESTER COMPLEX AND LIGANDS

Same distribution

Absorption tail of b-ketoester ligands slightly
overlapped with theregion of the emission ofanisole.
日本物理学会 第６９回年次大会

Mar 27th, 2014

8

BACK SCATTERING METHODSingle peak could be usedeven in liquid scintillator.
日本物理学会 第６９回年次大会

Mar 27th, 2014

9

LIGHT YIELD OF LS CONTAINING ZIRCONIUMCOMPLEX AS A FUNCTION OF CONCENTRATIONLight yield of Zr(iprac)4even with small bumprecovered about double
compared with Zr(acac)4.
Light yield at 10w.t.%
concentration wasalmost 40% to BC505(≒ standard cocktail) ,If the small bump could
be removed.
日本物理学会 第６９回年次大会

Mar 27th, 201410

ENERGY RESOLUTION OF LS CONTAININGZIRCONIUM COMPLEX AS A FUNCTION OF
CONCENTRATION
Photo coverage : ~8.5%(see explanation slide)
Assuming 40% of photo
coverage, the energy
resolution will recover
6.5% @ 1MeV = 4.1%
@ 2.5MeV for 10 w.t.%
concentration.
They almost achieved
to our goal!.
日本物理学会 第６９回年次大会

Mar 27th, 201411

SUMMARY Confirmed that the absorption peak moved shorter

wavelength (275nm → 245nm) by introducing b-ketoester substituent groups.
 Small bump was found in absorption spectra. They
could be explained by impurities of complex, andwould be removed by purifying complex such assublimation.
 Anisole based liquid scintillator with 10 w.t.%
concentration of Zr(iprac)4 possibly has both 40% forlight yield to BC505 and 4.1%@2.5MeV (assuming 40%
photo coverage) for energy resolution, so that theyalmost achieved our goal!
 To improve light yield (and also energy resolution) ,we shall move the absorption peak around 210nm
using Zr(deml)4 “tetrakis (diethyl malonato) zirconium”.
日本物理学会 第６９回年次大会

Mar 27th, 2014

12

BACKUP日本物理学会 第６９回年次大会

Mar 27th, 201413

NEUTRINOLESS DOUBLE BETA DECAY[T1/20n(0+ ->0+)]-1 =G0n(E0,Z)|M0n|2<mn>2T1/2~a(Mt/DEB)

a: abundance

M: target masst: measurement time DE: energy resolution B: BG rate

Requirement : Low BG, Large target mass, High energyresolution
日本物理学会 第６９回年次大会

Mar 27th, 2014

14

SYNTHESIZE OF ZIRCONIUM BETA-KETO ESTERCOMPLEXZr(iprac)4
state: powderZr(etac)4
state : dry solid

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

Solubility > 10 w.t.% for anisole
日本物理学会 第６９回年次大会

Mar 27th, 201415

LIGHT YIELD OF LS CONTAINING BETA-KETO
ESTER LIGAND
Light yield recovered
about 50% comparedto the Zr-keto estercomplex due to vanish
the small bump.
However, a quenchingoccurred due to theabsorption tail.

日本物理学会 第６９回年次大会

Mar 27th, 2014

16

TETRAKIS (DIETHYL MALONATO) ZIRCONIUM
AND ABSORBANCE SPECTRUM OF LIGAND
Zr(CH3CH2OCOCHCOOCH2CH3)4= Zr(demｌ)4 mw : 727.87

shorter wavelength (~210nm)
日本物理学会 第６９回年次大会

Mar 27th, 201417

LIGHT YIELD OF LS CONTAINING DIETHYL
MALONATO LIGAND
No quenching due tooverlap between theabsorption of ligand andthe emission of anisole
should be occurred.

Perfect!
日本物理学会 第６９回年次大会

Zr(deml)4 will be an
ultimate complex if thesolubility becomes over10w.t.% for anisole.
Mar 27th, 201418

ABSORBANCE SPECTRA OF ZIRCONIUM BETAKETO ESTER COMPLEX FOR VARIOS POSITION
Small bump disappeared
after ~ 1 week.
These could be some
impurities of Zr complex
and they precipitated onbottom of the vial.

日本物理学会 第６９回年次大会

Mar 27th, 201419

ATTENUATION LENGTH OF ANISOLE
Attenuation length oflight from POPOP wasobtained as ~6m. It isalmost equivalent withthe detector size.

日本物理学会 第６９回年次大会

Mar 27th, 201420

PHOTO COVERAGEScintillation light wasguided to PMT via theacrylic light guide.
From the computer
simulation, the solid
angle was obtained as
8.5% for 4p area.

日本物理学会 第６９回年次大会

Mar 27th, 201421

PHOTO COVERAGE
Scintillation light wasguided to PMT via theacrylic light guide.
From the computer
simulation, the solid
angle was obtained as
8.5% for 4p area.

日本物理学会 第６９回年次大会

Mar 27th, 201422

Light yield calculation
Light yield = L0 ×s1Nppo
s1Nppo + s2NZr

L0 : Light yield of anisole
Nppo : No. of PPO molecular
NZr : No. of Zr(acac)4 moleculars1: absorbance of PPO
s2 : absorbance of complex

日本物理学会 第６９回年次大会

Mar 27th, 2014

23

ZIRCONIUM Β-DIKETON COMPLEX
 Zirconium(IV)acetylacetonate (Zr(acac)4)
 Advantage
 good solubility (over 10w.t.%)

in Anisole (PhOMe) Stable and cheep Commercial product Disadvantage
 Low scintillation light yield

Molecular weight : 487.66
日本物理学会 第６９回年次大会

due to overlap theabsorption of ligand andemission of anisole.
Mar 27th, 201424

WHAT’S PROBLEM
 Absorption spectra ofIn(acac)3 (indium acetylacetone) was overlappedwith the emission spectrafrom Anisole （Chem. Phys.
Lett., 435(2007), 252)

Same overlap between the emission
and the absorption could be occurred
even if different metal (Zr) was used.
日本物理学会 第６９回年次大会

Mar 27th, 201425

PHOTO LUMINESCENCE AND ABSORPTION OFPPO Photo luminescence Fluorescence device: HORIBA

FluoroMax-4

 Absorbance device : HITACHI

U-3000 Solvent : Benzonitrile (PhCN) Concentration : 1.0×10-5mol/L 2,5-Diphenyloxazole

 Molecular mass : 221.26
 Max. emission wavelength :368.0nm

 Max. absorption

wavelength : 309.7nm

日本物理学会 第６９回年次大会

Mar 27th, 201426

PHOTO LUMINESCENCE AND ABSORPTION OFPOPOP Photo luminescence Fluorescence device: HORIBA

FluoroMax-4

 Absorbance device : HITACHI

U-3000 Solvent : Benzonitrile (PhCN) Concentration : 1.0×10-5mol/L 1,4-Bis(5-phenyloxazol-2-yl)benzene

 Molecular mass : 364.40
 Max. emission wavelength :423.6nm

 Max. absorption

wavelength : 364.1nm

日本物理学会 第６９回年次大会

Mar 27th, 201427

PHOTO LUMINESCENCE AND ABSORPTION OFBIS-MSB
 Photo luminescence Fluorescence device: HORIBA

FluoroMax-4

 Absorbance device : HITACHI

U-3000 Solvent : Benzonitrile (PhCN) Concentration : 1.0×10-5mol/L 1,4-Bis(2-methylstyryl)benzene

 Molecular mass : 310.44
 Max. emission wavelength :426.6nm

 Max. absorption

wavelength : 355.3nm

日本物理学会 第６９回年次大会

Mar 27th, 201428

Piquemal@n2012

日本物理学会 第６９回年次大会

Mar 27th, 2014

29

FOR FUTURE EXPERIMENTS

high energy
resolution
4%@2.5MeV

F.Piquemal@n2012

http://kds.kek.jp/getFile.py/access?contribId=37&sessionId=16&resId=2&materialId=slides&confId=9151~tons of target will be necessary for next generation detector
日本物理学会 第６９回年次大会Mar 27th, 201430