The AMoRE double beta decay experiment

AMoRE (Advanced Mo-based Rare process Experiment)

HongJoo Kim (KyungPook National Univ.) On behalf of AMoRE collaboration

Apr 22-25, 2014,

WE-Heraeus-Seminar on ‘Massive Neutrino’, Physikzentrum Bad Honnef/Germany

Double beta decay process

2n bb decay 2nd order beta decay Rare nuclear decay (>1018 years)

0n bb decay 1) n mass>0 & Majorana particle 2) New Physics

e ν

e

ν N

N’

2νββ

e ν e ν

N N’

0νββ

A B

Transition bb

allowed

Forbidden b transition

Z

Energy

Z Z+1 Z+2

Q

bb

100Mo

100Ru

100Tc

Mass*Time (kg year)1 10 210

310

(y

ea

r)

1/2

T

2510

2610

2710

2810FWHM=5keV

DBU-4B=3x10

DBU-2B=1x10

DBU: counts/ (keV kg year)

AMoRE Experimental sensitivity

T1/2

0n (exp) = (log2)Na

a

Ae

MT

nCL

T1/2

0n (exp) = (log2)Na

a

Ae

MT

bDE

Isotopic

Abundance

Atomic

mass Background level

(count/keV kg year)

Energy

Resolution

Time

Detector Mass

Detection

Efficiency

For “zero” background case; # of background events ~ O(1)

For sizeable background case;

AMoRE10kg

AMoRE200kg

History of CaMoO4

1) 2002 : Idea and try to grow CMO in Korea

2) 2003 : Collaboration with V.Kornokov. Received CMO (better)

3) 2004 : CMO test and Conference presentation (VIETNAM2004),

Extended idea of XMoO4, cryogenic detector of CMO

4) 2005-2007 : Large CMO with 1st ISTC project

5) 2006 : Collaboration with F. Danevich group (CMO by Lviv)

6) 2007 : CMO R&D in cryogenic temperature started.

7) 2008 : 2nd ISTC project : 1kg of 48deplCa100MoO4 crystal

8) 2009 : AMORE collaboration formed

9) 2010-11 : 48deplCa100MoO4 internal background study

10) 2012 : Russian group got funding for CMO production line

11) 2013 : AMoRE project funded (Under IBS CUP)

•Proc. New View in Particle Physics (VIETNAM ’2004) Aug. 2004, p.449 •IEEE Nucl. Sci. 52, 1131 (2005) •NIMA 584, 334 (2008) •IEEE Nucl. Sci. (2010,2012)

AMoRE Collaboration (Sept 2013) • Korea (56) Seoul National University : H.Bhang, S.Choi, M.J.Kim, S.K.Kim, M.J.Lee, S.S.Myung, S.Olsen, Y. Sato, K.Tanida,

S.C.Kim, J.Choi, H.S.Lee, J.H.Lee, J.K.Lee, X.Li, J.Li, H.Kang, H.K.Kang, Y.Oh, S.J.Kim, E.H.Kim, K.Tshoo, D.K.Kim(23) Kyungpook national University : H.J.Kim, Y.S.Hwang, S.J. Ra, J.Y.Lee, S.Khan, L. Ali, R. Bibi, J.H. So(8) Sejong University : Y.D.Kim, E.-J.Jeon, K. Ma, J.I.Lee, W.Kang, J.Hwa (6) Korea Research Institute of Standards and Science : Y.H.Kim, G.B. Kim, K.B. Lee, M.K. Lee, W.S. Yoon, H.J. Lee, S.J.

Lee, Y.S. Jang, Y.N. Yuryev, H.S.Park, J.H.Kim, J.M.Lee (12) Ehwa Woman’s University: I.S.Hahn, H.S.Lee (2) Sungsil University: M.-K. Cheoun, E.J. Ha, K.S. Choi (3) Semyung University: S. J. Kang (1) Chung-Ang University: S. Y. Kim (1) • Russia (18) ITEP(Institute for Theoretical and Experimental Physics) : V.Kornoukhov, P. Polozov, N.Khanbekov (3) JSC-FORMOS Materials : V.V. Alenkov, O.A. Buzanov (2) Baksan National Observatory : A.Ganggapshev, A.Gezhaev, V.Gurentsov, V.Kuzminov, V.Kazalov, O.Mineev,

S.Panasenko, S.Ratkevich, A.Verensnikova, S.Yakimenko, N.Yershov, K.Efendiev, Y.Gabriljuk (13) • Ukraine(11) INR(Institute for Nuclear Research) : R.S. Boiko, D.M. Chernyak, F.A. Danevich, V.V. Kobychev, V.M. Mokina, D.V. Poda, R.B. Podviyanuk, O.G. Polischuk, V.I. Tretyak (9) • China(3) Tsinghua University : J.Li, Y. Li, Q.Yue(3) • Germany(3) University of Heidelberg : C.Enss, A. Fleischmann, L. Gastaldo (3) • Parkistan(1) Abdul Wali Khan Univ : G. Rooh (1) 6 countries(+1), 15 institutions, 90 collaborators

Korea Hydro & Nuclear Power Co.

Yangyang Pumped Storage Power Plant

Yangyang(Y2L) Underground Laboratory

Minimum depth : 700 m / Access to the lab by car (~2km)

(Upper Dam)

(Lower Dam)

(Power Plant)

KIMS (Dark Matter Search)

AMoRE (Double Beta Decay Experiment)

Seoul

Y2L

700m

1000m Samchuk

CaMoO4 crystal development

2.2

cm

Korea(2003) Ukraine-CARAT(2006) Russia(2006)

30x30x200mm

IEEE/TNS 2008

CaMoO4 Characterization:

4% FWHM at 3 MeV Only with photoelectron statistics

NIMA 584, 334 (2008)

IEEE TNS 57 (2010) 1475

Temperature dependence of CaMoO4

CMO absolute light yield @RT: 4900+-590 ph/MeV (H.J. Kim et al., IEEE TNS 57 (2010) 1475)

-> Light yield at cryogenic temp. : ~ 30,000 ph/MeV -> Highest light yield among Mo contained crystals.

From RT to 7K, light yield increase factor 6 (V.B. Mikhailik et al., NIMA 583 (2007) 350)

100Mo, 48deplCa materials

Mo-100 isotope production: The ECP (Electrochemical plant) Zelenogorsk, Krasnoyarsky kray, Siberia

• 100MoO3 oxide with mass of Mo-100 : 2,5 kg

Enrichment: Mo-100 = 96,1%

Impurities (the results from ICP MS measurements): U <= 0.00007 ppm (< 0,07 ppb) and <= 0.0002 ppm (< 0,2 ppb)

Th <= 0.0001 ppm (< 0,1 ppb) and <= 0.0007 ppm (< 0,7 ppb) 226Ra < 2,3 mBq/kg, 228Ac < 3,8 mBq/kg

Current capacity is 25-30 kg per year.

Other option for 100Mo : URENCO Co. R&D stage for production

The industrial separator SU20 Lesnoy, Sverdlovky region

27 kg of Ca-48depl (48deplCaCO3) is available now at EKP, Lesnoy

Ca-48 < 0,001%

48deplCa100MoO4 crystals from FOMOS Co.

• SB28

weight 196 g

• SB29

weight 390 g

• S35

weight ~300 g

• SS68

weight ~300 g

New S68 Under test (Nb doped)

4p CsI(Tl) active setup with Pb shielding at Y2L

1) 2n EC+b+ , b+b+ study with 2 back to back g tagging (1) Sr-84 : SrCl2 (4.6x10

17 yr by 90%CL)

(2) Mo-92 : CaMoO4 (2.3x1020 yr NIMA 654, 157 (2011))

2) CMO internal background study with active veto

CsI(Tl) 6cm

Low background Pb (10cm)

EC+b+ , b+b+

Crystal

511keV g

511keV g

Internal background levels from Y2L

214Po : 1.93-MeV, 1.74mBq/kg

216Po : 1.62-MeV, 0.26mBq/kg

220Rn : 1.44-MeV

210Po : 1.13-MeV

214Po : 1.93-MeV, ≈ 0.08mBq/kg

216Po : 1.61-MeV, ≈ 0.07mBq/kg

220Rn : 1.45-MeV

214Po : 2.10 MeV, ≈ 2.83 mBq/kg

216Po : 1.74 MeV, ≈ 0.043 mBq/kg

220Rn : 1.58 MeV

210Po : 1.20 MeV

S35

SB28 CARAT#1

b-a decay in 238U 214Bi (Q-value : 3.27-MeV) → 214Po (Q-value : 7.83-MeV)

a-a decay in 232Th 220Rn (Q-value : 6.41-MeV) → 216Po (Q-value : 6.91-MeV)

CARAT#1 (from Ukraine)

(5343)50 mm, 411 g

New SS81(FOMOS) will be delivered for final qualification

Sensitivity of 0n DBD using S35

7.3% of FWHM resolution on 3035-keV.

3 counts were come from 214Bi decay.

6.52 counts/keV·kg·year

About 70 days data

.

Plan upgrade for AMoRE

1st stage : room temperature

6kg 48deplCa100MoO4 , 5% FWHM

3 years, 6.0 x 1024 y (90% CL)

2nd stage : Cryogenic technique

5 years, 100 kg 48deplCa100MoO4

Pilot : Cryogenic technique

1kg 48deplCa100MoO4 (AMRE-1)

1st stage : Cryogenic technique

10kg 48deplCa100MoO4 (AMORE-I)

2nd stage : Cryogenic technique

200 kg 48deplCa100MoO4 (AMORE-II)

Mo-100 2n

Tl-208

Bi-214

Signal (m=0.4eV)

MMC (Metallic Magnetic Calorimeter) for LTD

Principle of operation

1. Energy absorption in CMO crystal.

2. Phonon & Photon generation.

3. Temperature increase (gold film).

4. Magnetization of MMC decrease.

5. SQUID pickup the change.

Advantage of MMC

Fast rising signal. (critical for lower

2nbb random coincidence.)

Fairly easy to attach to absorber.

Excellent Energy resolution

paramagnetic sensor:

Au:Er

CaMoO4

MMC Phonon sensor

Light sensor

Si or Ge MMC

Collaboration with Heidelberg group * Talk by Loredana, Poster by Mathias

KRISS Setup (over ground)

Photon detector

A MMC chip

Large CMO crystal (216 g) was tested * SB28 (enriched CMO) is under installation.

Pulse shape by MMC

• Signals showed 0.5 ms rise-time at 30 mK.

• Fast rise-time is quite important for 2nbb random coincidence rejection.

• Faster rise-time than bolometer technique.

Background energy spectra at surface

19

Energy (keV) 511 1461 2615

FWHM (keV) 8.0 1.2 8.2 1.1 9.0 1.9

Comparison of Pulse Shape for α/β

Phonon-Photon Measurement

• We measured light signals but they are very small because of small covering area (5 mm × 5 mm).

• α and β particles show different light yield.

• We are developing 2 inch Ge photon sensor

P r e l i m i n a r y P r e l i m i n a r y

Background alpha energy spectra

• Internal alpha background events from non-enriched crystal.

GEANT4 Simulation of for AMoRE @ Y2L

▪ CaMoO4 48deplCa 100%, 100Mo 100% cell size: D(5cm)xH(5cm) 0.426kg Total 432 (6 x 6 x 12 array) 184kg

▪ CaMoO4 support : Cu (1cm, ring structure)

Shielding 20cm PE + 10cm Scin + 15cm Pb + 1cm Al + 5cm Pb + 1cm Cu+

Major backgrounds from radionuclides: (GEANT4) Background source Activity

[ µBq/kg]

Bg

[10-4 cnt/keV/kg/yr]

Bg reduced by PSD

[10-4 cnt/keV/kg/yr]

Tl-208, internal 10 (232Th) 0.36

Tl-208, in Cu 16 (232Th) 0.22

BiPo-214, internal 10 0.11 1) ≤ 0.01

BiPo-214, in Cu 60 1.8 1) 2) ≤ 0.18

BiPo-212, internal 10 (232Th) 0.08 1) ≤ 0.01

BiPo-212, in Cu 16 (232Th) 0.36 1) 2) ≤ 0.04

Y-88, internal 20 0.19

Σ int. (w/o 2β2ν ) 0.74 ≤ 0.57

Σ Cu 2.40 ≤ 0.44

Rand. coinc. from 2β2ν

decays of 100Mo

8.7×103

(single evts.)

3.13) 1.2

Total 6.2 ≤ 2.2

1) Can be reduced x0.1 by alpha/beta PSD

2) Can be reduced by teflon coating of Cu (to remove surface alphas)?

3) Can be reduced by the leading edge separation with Δt=0.5 ms

Muon background : ~1.4e-4 counts/keV/kg/yr @Y2L

For ultra-low background crystal

Crystal growing optimization (Size and quality)

Powder purification

ICP-MS No

Yes

Crystal growing

Scintillation (Phonon)

No

Yes

Re-crystalization

K1 chemical & Clean room

Seoul U. and other labs

K1 lab.

Y2L Underground lab Baksan lab

Company (K1 lab.)

Ultra-low background powder R&D is difficult and need quick feedback

• We plan to have new Czochalski, Kyropoulous and Bridgman crystal growing equipment • Each crystal growing method has different characteristics Main goal. 1) CaMoO4 purification & crystal growing R&D for AMoRE-II 2) Other double beta decay or dark matter search crystal R&D

Low background Crystal growing facility

48Ca Enrichment/Depletion at KAERI (Korea Atomic Energy Research Institute)

ALSIS (Advanced Laser Stable Isotope Separation)

-> AMoRE-Ca (48CaMoO4 crystal) for 48Ca 0-DB search

Possible

70W 544nm

10W 272nm

<Laser> <Separation Chamber>

20W 535nm

1070nm

200W 528nm

1056nm

150kHz 5W

150kHz 5W

70W

400W

500kHz 20W 200W

Atomic Beam Generator

Tail Collector

Extractor

Beam delivery

1089nm Freq. Lock

Dark matter sensitivity of CaMoO4 cryogenic experiment : AMoRE-DARK

CoGent CRESST

AMoRE-Dark 200kg

XENON1T

CDMS

XENON

SuperCDMS Buchmueller et al.

Trotta et al.

KIMS

upgrade

For AMoRE-1, I, II

For AMoRE-1 1kg Enriched CMO is ready, plan to install Cryogenic setup by the end of this year and start to taking a data on summer 2015.

For AMoRE-I Waiting for qualification of Enriched CMO by FOMOS

in Summer, 2014 ( 50 uBq/kg for U-238,Th-232)

For AMoRE-II 1. We need to develop deep purification & recovery of Ca-40 and Mo-

100 with high efficiency and enrich CMO crystal background need to be reached factor 5 down from AMoRE-10 requirement ( from 50 uBq/kg to 10 uBq/kg)

2. Need to find the most efficient technology of CMO growing (Czochalski, Low gradient CZ, Kyropoulous, Bridgman)

3. AMoRE-II will be installed deeper underground site

30

Y2L Laboratory Upgrade plan

• AMoRE-1, AMoRE-I will be constructed here • There are KIMS-NaI, low background 4pi-detector and

HPGe setup will be constructed

Summary and Prospect

• Large volume of low background 48deplCa100MoO4 have been developed and characterized.

• Cryogenic MMC technique with CMO is successful.

Prospect 1) AMoRE-1 : AMoRE-1kg will be started next year and will reach NEMO3 sensitivity of 1.1x1024 y, Mn<0.3-0.9 eV with one year data. (NEMO3: arXiv1311.5695v2 ; 34.7 kg*y)

2) AMoRE-I : AMoRE-10kg will be constructed within 3 years and reach the sensitivity of 3x1025 y (Mn <50-160 meV).

3) AMoRE-II : If AMoRE-I is successful, we will move to AMoRE-II (200 kg) and explore neutrino mass of 10-30 meV region (1027 y) with 5 years data taking

Thank you for attention

Backup slides

AMoRE is one of the best sensitive exp.

~1350m in the height

Mid basement

Entrance of Tunnel 240 m height with the sea level

New underground lab plan at Samchuk at Duta Mountain (~1350 m minimum depth)

Sea Level Ground Line

Underground Cavity

1.45km

1.45km Duta mountain

Theoretical Issues

1/T0n 1/2 = G0n(E0,Z) |M0n|2 <mbb>2/me

2

G0n(E0,Z) : phase space factor (~ Qbb5) : higher Q-value is better.

• M0n-Nuclear Matrix Element, hard to calculate

Model dependent

Motivation to measure several isotopes

Werner Rodejohann, Int. J. M. Phys., 2011

Decay time / Light output / Energy resolution of S35

S35

Resolution : 16% (FWHM)

Mean : 5.97 x 105

Natural CMO

Resolution : 16% (FWHM)

Mean : 6.79 x 105

SB28

Resolution : 30% (FWHM)

Mean : 2.88 x 105

Decay time of SB28

Decay time of S35

Decay time of Natural CMO

238U/232Th decay chains

a-decay of 214Po

Half life : 164 ms

a-decay of 216Po

Half life : 140 ms

b-a decay 214Bi → 214Po → 210Pb

a-a decay 220Rn → 216Po → 212Pb

Thermal quenching

• As temperature rises, intensity decreases and decay becomes faster as seen in a typical example of BGO, BSO, PbWO4, CsI, NaI, BaCl2

E vs Mean_time of S35

214Po : 1.93-MeV

216Po : 1.62-MeV 220Rn : 1.44-MeV

Trap centers in molybdates

Energy losses occurs at the stage of migration of charge carriers to the emission centers? S(CaMoO4) > S(ZnMoO4).

Subject of the presentation: Role of intrinsic traps in the energy transfer processes at low temperatures. Special attention is paid to ZnMoO4!

Q (CaMoO4) ~ Q(ZnMoO4)

Eg (CaMoO4) ~ Eg (ZnMoO4)

300 400 500 600 700

0.0

0.5

1.0

1.5

0.0

0.5

1.0

1.5

2.0

ZnWO4

CaWO4

Wavelength, nm

T = 10 K

emission of STE under direct excitation

ZnMoO4

CaMoO4

Inte

nsity,

a.u

. D.A. Spassky SCINT2013, 16/04/2013, Shanghai

Absorber

Thermometer

Thermal link

Heat sink < 100 mK

a, b, g, etc.

Energy absorption Heat (Temperature)

Choice of thermometers Thermistors (doped Ge, Si) TES (Transition Edge Sensor) MMC (Metallic Magnetic Calorimeter ) STJ, KID etc.

Total deposited energy measured Ultimate energy resolution.

Basic idea of Low Temperature Detectors

44

Dilution refrigerator for AMoRE-10 (Ordered)

Plots for all material backgrounds

2nbb random coincidence

Total internal

Total Cu

Total Cu

Total internal

Segregation of radioactive elements

The scraps after the 116CdWO4 crystal grown

were measured by HPGe g detector

Matthias Laubenstein (LNGS)

Segregation of impurities

K = CS/CL,

where K is segreagation coefficient, CS is concentration of impurity in solid phase (crystal), CL is concentration of impurity in liquid phase (melt),

If K < 1, recrystallization could improve radiopurity of the crystal

Radionuclide Crystals [1] Scraps [*]

228Th 0.06 10(2)

226Ra <0.005 64(4)

40K <1 27(11)

Crystal

Melt

Radioactive contamination (mBq/kg)

Readout electronics and DAQ

AMoRE-ADC module development

1 Input: ±10 V, 1 Mohm termination

2 16 ch/module, stand alone

2. Variable attenuator

3. 18 bit, 2 Msa/s

4. 4 Gbyte DDR3 DRAM buffer

5. Digital processing and trigger

6. Continuous sampling possible