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

IPNOS for low energy solar
neutrinos and ZICOS forneutrinoless double beta decay
Aspen Winter Workshop--New Directions in Neutrino Physics
February 4th ,2013
Yoshiyuki FUKUDA (Miyagi University of Education)
S.MORIYAMA , H.Sekiya(ICRR, Univ. of Tokyo) I. Ogawa (FukuiUniversity), T.Namba(ICEPP, Univ. of Tokyo), andM.Asakura ,T.Izawa(Hamamatsu Photonics KK)

Indium Project on Neutrino
Observation for Solar Interior(IPNOS) experiment for low
energy solar neutrinos

Feb 4th, 2013

Aspen Winter Workshop--New
Directions in Neutrino Physics

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Solar neutrino

Takeuchi @ LowNu2011

Overall reaction: 4 p4He  2e  2 e  25MeV
p-p chain

CNO cycle

 Solar fusion cross sections are updated. (SF-II, Rev. of Mod. Phys. 83 (2011) 195)
 Solar abundances: GS98 (High metallicity), AGSS09 (Low metallicity)
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Takeuchi @ LowNu2011
Experimental statuslong term stability of pp rate (cf. PRC 80, 015807 (2009))

 pp(0.6%):

 7Be(7%):
 pep(1.2%):
 8B(14%):

 hep(30%):

SAGE (all:5%,pp:14%), Gallex/GNO
Homestake, Borexino (5%)
Borexino (19%)
Kamiokande, Super-K, SNO (4%),
Borexino, KamLAND high precision spec. & d/n(SK, SNO, upper limit only)
SK: 40x10^3 /cm2/s (90%CL, w/o osc.) PRL 86, 5651 (2001)
SNO: 23x10^3 /cm2/s (90%CL, w/ osc.) ApJ 653, 1545 (2006)

 CNO (14~17%): (Borexino, upper limit only)
7.7x10^8 /cm2/s (95%CL, w/ osc.) arXiv:1110.3230

purification efforts are now on-goingradiochemical experiments
theoretical / experimental
uncertainties
Aspen Winter Workshop--New
4 4th, 2013
Feb

Directions in Neutrino Physics

runningCurrent targets

Takeuchi @ LowNu2011
SKBorexino

Neutrino physics
SAGE Vacuum-MSW transition
 pep flux(ES,CC), 8B spectrum, …

 Precise theta12
 pp flux, 8B spectrum, …

Astrophysics

arXiv:1110.3230

 Separate solar models
 CNO fluxes

 Solar core high stat. solar Feb 4th, 2013

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Future solar neutrino projects Takeuchi @ LowNu2011
project

target for solarcurrent status / recent information

pep/CNO (ES)
SNO+ 1kt LS

KamLAND2 1kt LS

under construction

will be after KamLAND-Zen

pp(ES)XMASS 10 ton(FV) Lq.
Xecommissioning of XMASS-I (total 1ton,~0.1ton FV)

CLEAN 50 ton Lq. Ne

MiniCLEAN is under construction

HERON 10 ton Lq. He

will not built a full detector (Astropart. Phys. 30, 1(2008))

pp/7Be(CC)LENS 10ton 115In

R&D (In loaded LS)

IPNOS 115In

R&D (InP cell + Lq. Xe detector)

MOON 1.5~3ton 100Mo

R&D (EC branch of 100Tc was measured)

Next generation
Water Cherenkov
6Megaton water

Lq. Scintillator ~0.1Mton LS

LOI from Hyper-K (arXiv:1109.3262)
white paper from LENA (arXiv:1104.5620)

Capture of low energy solar neutrinos by 115In
R.S.Raghavan Phs.Rev.Lett37(1976)259● Advantage
・ large cross section (~640SNU)
・ direct counting for solar neutrinos
・ sensitive to low energy region(E ≧ 125keV)・ energy measurement (Ee = E － 125keV)・ triple fold coincidence to extract neutrinosignal from huge BG (e1 +g2 + g3 )● Disadvantage
・ natural b-decay of 115In(t1/2 = 4.4 × 1014 yr , Ee≧498keV)・ possible BG due to correlated
coincidence by radiative Bremsstrahlung

GoalNuclear Physics A 748 (2005) 333-347

e115Sn*(4.76ms) → 115Sn +g1(115keV) + g 2(497keV)
115In +Feb 4th, 2013

→ 115Sn* + e-

1.
2.
3.

Good energy resolution :10%(FWHM)
Fine segmentation (104-105)
High efficiency g detection

Aspen Winter Workshop--New
Directions in Neutrino Physics7Semi-insulating InP detector

Indium-Phosphorus(200mm)mounted in vacuum dewar

Semi-insulating InP VCZ
substrate by Sumitomo
Electric Industrials
 Assembled by Hamamatsu
Photonics
 Operation at -79degreeFeb 4th, 2013

Surface size:
・10mm×10mm×0.2mm
・6mm×6mm×0.2/0.23/0.28/0.45mm
Electrode :・ Ohmic contact
・ evaporated Au/Cr base metal
・ Insulator (SiN) to avoid leak current

Aspen Winter Workshop--New
Directions in Neutrino Physics

8Gamma ray spectrum observed by InP Measured clear

photo- peak
 induced chargecollection(Led~200mm Lhe ~30mm)
 Energy of electronhole pair production:3.5eV Energy resolution :25%@122keV
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Aspen Winter Workshop--New
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9IPNOS phase-I experiment for low energysolar  experiment
InP multi-pixel detector inside of
Liquid Xenon (LXe) with PMTs

30cm cubic chamber (like XMASS
100kg prototype) includes ~10kg
InP detector~103 modules will be neededin the final IPNOS (~10ton InP)

Need larger area InP detector
Feb 4th, 2013

Aspen Winter Workshop--New
Directions in Neutrino Physics

10Development of LXe chamber for IPNOS
phase-I proto-type 24cc Liquid Xenon(LXe) in innerchamber
 4 InP detectors
mounted inside ofLXe
 PMT (used forXMASS) detects sci.
light from gammas
Feb 4th, 2013

Photo multiplierAspen Winter Workshop--New
Directions in Neutrino Physics

11Cooling test of Liquid Xenon chamber

Feb 4th, 2013

Aspen Winter Workshop--New
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12New InP crystal (low etch pit density)

EPD related to Lattice
Defect which generates
significant dark current

Feb 4th, 2013

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Zirconium Complex in Organic
liquid Scintillator (ZICOS) fordouble beta decay experiment

Feb 4th, 2013

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Neutrinoless double beta decay[T1/20(0+ ->0+)]-1 =G0(E0,Z)|M0|2<m>2
T1/2~a(Mt/DEB) a: abundance M: masst: meas.time DE: energy res. B: BG rate
Requirement : Low BG, Large target mass, High energy
resolution
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For future experiments

F.Piquemal@2012
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
Feb 4th, 2013

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16Piquemal@2012

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Neutrinoless double beta decay using
liquid scintillator
Experimental limits forneutrino mass

 Requirement for<m>: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 mass
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Detector concept design
 Spherical structure (Zr loaded 100ton LS)
Assuming 10w.t.% solubility

3m10m
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Aspen Winter Workshop--New
Directions in Neutrino Physics

19What’s problem
 Absorption spectra ofIn(acac)3 (indiumacetyl acetone) wasoverlapped with theemission spectra fromAnisole （Chem. Phys.
Lett., 435(2007), 252)
Same overlap of the emission and theabsorption spectrum would be occurred
even if different metal (Zr) was used.
Feb 4th, 2013

Aspen Winter Workshop--New
Directions in Neutrino Physics

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

Feb 4th, 2013

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

Aspen Winter Workshop--New
Directions in Neutrino Physics

PPO 100mg : 4.52X10-4 mol21

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

Feb 4th, 2013

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

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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
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Absorption spectra

Absorption peak of ketoOverlap with emission peakester complex

No overlap between emission and absorption
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Development for new LS for IPNOS
phase-II Liquid Scintillator

containing indium βketo ester complex

 Advantages

 Easy to scale up for

10ton In in 100ton LS Possible same design
as ZICOS Low energy solar  pp/7Be and CNO  Modulation using 7Be  Supernova  burst e burst form

Neutralization
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e from Neutralization burst -nucleus s115In has ~10-39 cm 2 for 20-100MeVcompared with see~10-43 cm2
Sensitive to neutralization burst

100ton of In detects 20-100 ev
 Nuclear synthesis (r-process)Rhy.Rev.C53(1996)1409

Feb 4th, 2013

  mass hierarchy
Aspen Winter Workshop--New
Directions in Neutrino Physics

26Summary InP detector for IPNOS phase-I needs more larger

area to reduce the number of channel.
new substrate will solve them.
 High solubility of Zr β-keto ester in Anisole(>~10w.t.%) for ZICOS detector was achieved.
 Confirmed absorption peak of beta-keto ester
complex moves to shorter wavelength (275nm →245nm).
no overlap with emission spectrafrom anisole.
 Indium β-keto ester complex will be developed forIPNOS phase-II to measure both low energy solar
neutrinos and supernova neutralization burst.
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