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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