AMoRE Neutrinoless Double Beta Decay Experiment

Report
Joint Winter Conference
on Particle Physics, String and Cosmology
YongPyong-High1 2015
The AMoRE Project
to search for 0 of 100Mo
using low temperature detectors
Yong-Hamb Kim (김용함)
- Center for Underground Physics, IBS
- KRISS
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The AMoRE Project
AMORE: ‘Love’ in Italian
AMORE: “A cosmetic company in Korea
AMoRE: Advanced Mo-based Rare process Experiment
to search for neutrinoless double decay of 100Mo
using cryogenic 40Ca100MoO4 detectors
Ø4cmx4cm
CaMoO4 crystal
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AMoRE collaboration
Institute for Basic Science, Daejeon, Korea
Korea Research Institute of Standards and Science, Daejeon, Korea
KyungPook National University, Daegu, Korea
Sejong University, Seoul, Korea Seoul National University, Seoul, Korea
Ewha Womans University, Seoul, Korea Chung-Ang University,
Semyung University, Korea
Soongsil University, Korea
Institute for Theoretical and Experimental Physics, Moscow, Russia
JSC Fomos-Materials, Moscow, Russia
Baksan National Observatory, Kabardino-Balkarskaya Republic, Russia
Institute for Nuclear Research, Kyiv, Ukraine
Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany
Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
Tsinghua University, Beijing, China Nakhon Rajabhat University, Thailand
Abdul Wali Khan University, Pakistan
Institut Teknologi Bandung (ITB), Indonesia
7 counties, 16 institutions, 90 collaborators
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Double beta decay
Double Beta Decay with two neutrinos
2νββ proposed by Maria GeoppertMayer in 1935.
First observed directly in 1987.
Why 50 years?
T1/2(2νββ) : 1019 ~ 1021 y
Background T1/2(U, Th) : 1010 y
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Neutrinoless double beta decay (0νββ)
Double Beta Decay with two neutrinos
Double Beta Decay with no neutrino
requires massive Majorana ν !
Key test proposed by Racah in 1937
It may answer
- Mass of neutrinos ( 1 T10/2  m2 )
- Majorana (   ), or Dirac particles (   )
- Lepton number conservation
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Experimental Sensitivity of T1/2 (0)
For sizeable background case;
a
MT
T (exp) (ln 2) N a 
A bE
Background level
(count/keV kg year)
FWHM=5keV
AMoRE200kg
Time
1027
0
1/ 2
Atomic
mass
1028
Detector Mass
Energy
Resolution
T1/2 (year)
Isotopic
Abundance
Detection
Efficiency
B=3x10-4 DBU
B=1x10-2 DBU
AMoRE10kg
1026
1025
For “zero” background case;
# of background events ~ 0 (1)
a MT
T (exp) (ln 2) N a 
A nCL
0
1/ 2
DBU: counts/ (keV kg year)
1
10
102
Mass*Time (kg year)
10
3
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100Mo

is chosen for 0 experiment
100Mo
 High Q-value () of 3034.40 (12) keV.
 High natural abundance of 9.7%
 Relatively short half life (0) expected from theoretical
calculation
1
0
T1/2
  G0 M 0
2  m 


m
 e 
2
Barea et al., Phy. Rev. Lett. 109, 042501 (2012)
Candidate
Q (MeV)
Abund. (%)
48Ca
4.271
0.19
76Ge
2.040
7.8
82Se
2.995
8.7
100Mo
3.034
9.7
116Cd
2.802
7.5
124Sn
2.228
5.8
130Te
2.533
34.1
136Xe
2.479
8.9
150Nd
3.367
5.6
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AMoRE detector technology
40Ca100MoO
Low Temp. Detector
Source = Detector
MMC
Light sensor
4
+ MMC
CaMoO4
- Scintillating crystal
- High Debye temperature: TD = 438 K, C ~ (T/TD)3
- 48Ca, 100Mo 0ν candidates
- AMoRE uses 40Ca100MoO4 w. enriched 100Mo and
depleted 48Ca
CaMoO4
MMC
phonon
sensor
<10-50 mK>
MMC (Metallic Magnetic Calorimeter)
- Magnetic temperature sensor (Au:Er) + SQUID
- Sensitive low temperature detector with highest
resolution
- Wide operating temperature
- Relatively fast signals
- Adjustable parameters in design and operation stages
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2.2 cm
CaMoO4 crystal development
Korea(2003)
Ukraine-CARAT(2006)
Russia(2006)
IEEE/TNS 2008
30x30x200mm
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Temperature dependent scintillation
From RT to 7 K, the light yield increases 6 times
(V.B. Mikhailik et al., NIMA 583 (2007) 350)
CaMoO4 absolute light yield @RT: 4900590 ph/MeV
(H.J. Kim et al., IEEE TNS 57 (2010) 1475)
 Light yield at low temp. : ~ 30,000 ph/MeV
 Largest light yield among Mo contained crystals.
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100Mo, 40Ca
enriched materials
 Mo-100 isotope production:
ECP (Electrochemical plant) Russia
URENCO Netherland
100MoO
3
100Mo = 97%
- Enrichment:
- Impurities
ICP-MS measurement: U  0.2 ppb, Th  0.1 ppb
HPGe At Baksan: 226Ra < 2.3 mBq/kg, 228Ac < 3.8 mBq/kg
 Ca-40 isotope production:
ELEKTROCHIMPRIBOR, Lesnoy, Russia
40CaCO
3
- 48Ca < 0.001%
- Impurities: U ≤ 0.1 ppb, Th ≤ 0.1 ppb, Sr = 1 ppm, Ba = 1 ppm
226Ra = 51 mBq/kg 228Ac(228Th) = 1 mBq/kg
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40Ca100MoO
4
• SB28
weight 196 g
• SB29
weight 390 g
crystals
• S35
weight ~300 g
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Internal backgrounds of 40Ca100MoO4 crystals
4p CsI(Tl) active setup with Pb shielding at Y2L
4p gamma veto system
a decay in 238U
214Bi
(Q-value : 3.27-MeV) → 214Po (Q-value : 7.83-MeV)→ 210Pb
aa decay in 232Th
220Rn
(Q-value : 6.41-MeV) → 216Po (Q-value : 6.91-MeV)→ 212Pb
Crystal S35
210Po
Crystal SB28
: 1.13-MeV
216Po : 1.62-MeV, 363 events,
0.26mBq/kg
214Po
: 1.93-MeV,
2445 events, 1.74mBq/kg
220Rn
: 1.44-MeV
214Bi
214Po
: 1.93-MeV, 63 events, 0.08mBq/kg
216Po
: 1.61-MeV, 57 events, 0.07mBq/kg
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Solid State Detectors
Thermometer
Thermometer
Charge
collector
Light
detector
Semiconductor
Scintillator
Measurement methods
Charge, Light, Phonon(Temperature)
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Measurement Chains in LTDs
Charge, Light, Phonon(Temperature)
 Low temperature favorable
Advantages of using LTDs for rare event search
• Low threshold & High resolution
• Active background rejection
examples
Events
Charge
Light
CRESST, Rucifer
AMoRE, LUMINEU
Phonon
CDMS, EDELWEISS
CUORE
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Low temperature detectors (Calorimeters)
Energy absorption  Temperature
Thermometer
Thermal link
Absorber
Heat sink < 1 K
Choice of thermometers
•
•
•
•
Thermistors (NTD Ge, doped Si)
TES (Transition Edge Sensor)
MMC (Metallic Magnetic Calorimeter )
etc.
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Metallic Magnetic Calorimeter (MMC)
Magnetic material Au:Er(100~1000ppm)
• weakly-interacting paramagnetic system
• metallic host: fast thermalization ( ~ 1ms)
g = 6.8
5 mT  Δε = 1.5 meV
1 keV  109 spin flips
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Highest resolution detector
Gold foil absorber
1.6 eV FWHM
for 6 keV x-rays
Au:Er
MMC chip
<2013 KRISS>
Am241 full spectrum
MMC with gold foil absorber
with C ~ 0.3kg CaMoO4
<2013 KRISS>
<2013 Heidelberg Univ.>
0.4keV FWHM
for 60keV 
1.2keV FWHM Gaussian width
for 5.5MeV a
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Phonon sensor for AMoRE
Phonon collector
Patterned gold film
MMC
Gold film
216 g CaMoO4
Gold wires
(thermal connection)
rise-time: ~ 0.5ms
We measure both thermal
and athermal phonons.
<Heat flow optimization>
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Photon sensor with MMC
Wafer holder
(Cu, heat bath)
Phonon collector
(Gold films)
MMC chip
SQUID sensor
Light absorber
(Ge wafer)
Temperature
independent risetime !
Thermal connection
rise-time:
~ 0.2 ms
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Detector Assembly
Phonon collector film
on bottom surface
196 g 40Ca100MoO4
(doubly enriched crystal)
Light detector
2 inch Ge wafer + MMC
Present detector being used in an over-ground lab (KRISS)
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Alpha and electron events
- Result summary PSD
Light/Heat ratio
[email protected]
[email protected]
Clear separation in
PSD and Light/Heat ratios!
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Pulse Shape Discrimination (phonon only)
[email protected]
17.5 
separation
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Light/Heat ratios
[email protected]
Ge
8.6 
separation
CaMoO4
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Energy spectrum
Energy (keV)
511
1461
2615
FWHM (keV)
4.3
5.7
8.7
YongPyong-High1 2015
YangYang(Y2L) Underground Laboratory
(Upper Dam)
26
YangYang Pumped
Storage Power Plant
Y2L
Seoul
1000m
700m
(Power Plant)
(Lower Dam
KIMS (Dark Matter Search)
AMoRE (Double Beta Decay Experiment)
Minimum depth : 700 m / Access to the lab by car (~2km)
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Lab space in Y2L
Some more lab space has been made at an unused tunnel
New Lab. Space
~ 1000 m2
KIMS (CsI) Lab. ~ 100m2
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Low Temperature LAB in Y2L
Jan. 2015
Dec. 2014
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Summary of the AMoRE project
•
•
•
•
•
•
Crystal: 40Ca100MoO4 , doubly enriched scintillating crystals
MMC technology for heat and light measurement
Temperature: ~20 mK
Zero background measurement in ROI
Location: Y2L (till Phase I) and a new lab (after)
Fully funded for Pilot, Phase I and II.
Pilot
Phase I
Phase II
Mass
1 kg
10 kg
200 kg
Sensitivity(mee) (meV)
300-900
60-180
10-30
Location
Y2L
Y2L
New Lab
Schedule
2015
2016
2019
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Scheduled AMoRE experiment
CMO: ~ 300g
5 layers-7 columns
5 CMOs: ~ 1 kg
<AMoRE Pilot, 2015>
<AMoRE10, 2016>
Each Cell : D=70 mm, H=80 mm.
CMO (D=50mm, H=60mm, 506g)
30 layers(2.4 m height)-13 columns
or 20 layers(1.6 m height)-19 columns
<AMoRE200, 2019>
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AMoRE Sensitivity & Competitiveness
AMoRE Pilot
Effective Neutrino mass (eV)
AMoRE 10
AMoRE 200
Lightest neutrino mass (eV)
Toward lower neutrino mass
Now
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We need larger space
Deeper place?
Hwaak
Y2L
Myungji
Mt. Duta
Mt. Jang
IBS
Mt. Daeduk
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SARF(Samcheok Astro-particle Research Facility)
A proposal for new underground lab for future projects
N
Mt. Duta
S
미로면 고천리 대방골
20m
40m
해발 180 m
미로면삼거리 구룡골
80m
15m
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감사합니다

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