SuperNEMO status Arnaud Chapon on behalf of the NEMO/SuperNEMO collaboration LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France
17 June 2011
s u p e r n e m o
collaboration
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Contents
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2
3
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Double beta decay The two decay processes Experimental principle The SuperNEMO experiment SuperNEMO design R&D developments Conclusion Summary
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Double beta decay The two decay processes
The allowed 2ν process (2ν2β)
The 0ν process beyond the SM (0ν2β)
(A,Z) → (A,Z+2) + 2e− + 2ν¯e
(A,Z) → (A,Z+2) + 2e−
∆L = 0
∆L = 2
ν 6= ν¯
ν ≡ ν¯
2ν −1 (T1/2 ) = G2ν |M2ν |2
0ν −1 (T1/2 ) = G0ν |M0ν |2 |mββ |2
2ν T1/2 ≈ 1019 − 1021 years
0ν T1/2 & 1024 years
u d d
u d u
W− W− d d u
u d d
e− ν¯e ν¯e e−
W− W− u d u
d d u
Fig.: 2ν2β mechanism A. Chapon
u d u
e− νe = ν¯e e− u d u
Fig.: 0ν2β mechanism SuperNEMO status
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Double beta decay Experimental principle
1.0
0.8
0.6
0.4 2ν2β spectrum
0ν2β signal
0.2
0.0
0.2
0.4
0.6
0.8
1.0
(Ee − +Ee − )/Qββ 1
2
Ideally a 0ν2β experiment should : measure the energy of the 2 electrons with very good energy resolution identify individually the 2 electrons emitted (Ee1 , Ee2 & cos θ)
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Double beta decay Experimental principle
The tracko-calo technique enables : Reconstruction of final state topology :
Source is separated from the detector : can measure several ββ isotopes
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ca
lor
im
et er
β−
~ B
te d
Background rejection and measurement through particle identification : e − , e + , γ, α
β−
en
I
m
I
Particle individual energy and TOF
Se g
I
Charged particle trajectory
ck Hig in h g gr vo a n lu ul m ar e ity
I
Decay vertex
tra
I
e ± individual energy charged particle trajectory time of flight magnetic field curvature angular distribution vertex
β β Mo so dul ur ar ce th fo in il
I
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The SuperNEMO experiment SuperNEMO design
1 disfavoured by 0ν2β
SuperNEMO limits 2 ∆m23 0
10-3 99% C.L. (1 dof) 10-4 -4 10 10-3 10-2 10-1 lightest neutrino mass in eV
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SuperNEMO goals : disfavoured by cosmology
|mee | in eV
10-1
reach a sensitivity ≈ 50 meV on the effective neutrino mass test the inverted hierarchy
1
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The SuperNEMO experiment SuperNEMO design
≥ k. A
0ν T1/2
Experimentally :
s
M.t Nbgr .r
ln2.NA : constant, : efficiency, A : molecular weight, M : source mass, 1.64 t : time of measurement, Nbgr : background events and r : energy resolution with k =
high Qββ I I
208
Eγ ( Tl) = 2.6 MeV Qβ (214 Bi) = 3.3 MeV
high G0ν (low
Qββ
nat. ab.
2ν T1/2
G0ν
isotope
(keV)
(%)
(years)
(10−25 yr−1 )
4272
0.187
4.2×1019
2.44
2995
8.73
9.2×1019
1.08
3350
2.8
20.0×1018
2.24
3034
9.63
7.1×1018
1.75
2805
7.49
3.0×1019
1.89
130
Te
2528.9
33.8
9.0×1020
1.70
136
Xe
2479
8.9
8.5×1021
1.81
150
Nd
3368.1
5.6
7.0×1018
8.00
48
Ca
82
Se
96
Zr
2ν high T1/2 (low 2ν2β)
100
high mass :
116
I I I
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0ν T1/2 )
2β
natural abundance low atomic mass A enrichment feasibility
Mo Cd
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The SuperNEMO experiment SuperNEMO design
NEMO3
SuperNEMO 82
100
Mo
Se
isotope
or 48Ca or 150Nd
7kg
isotope mass
100kg
18%
efficiency
30%
internal contaminations in the ββ foils Rn in the tracker
Tl : ≤2µBq/kg Bi : ≤10µBq/kg Rn : ≤ 0.15 mBq/m3
8% @ 3MeV
calorimeter resolution
4% @ 3MeV
0ν T1/2 & 1 × 1024 yr hmν i < (0.3 - 0.9) eV
sensitivity
0ν T1/2 & 1 × 1026 yr hmν i < (0.04 - 0.11) eV
208
Tl : ≈ 100µBq/kg Bi : < 300µBq/kg Rn : 5 mBq/m3
214
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214
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The SuperNEMO experiment SuperNEMO design
20 modules surrounded by passive shielding
20 modules Source I
I
I
5kg per module ( 4 × 2.7 m2 , 40 mg/cm2 ) 82 2ν Se first (High Qββ , long T1/2 , proven enrichment technology) 48 Ca and 150Nd under consideration
Tracking detector I
Drift wire chamber in Geiger mode (2000 cells)
Calorimeter I
Fig.: SuperNEMO module
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600 plastic scintillators coupled to low radioactivity PMTs
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The SuperNEMO experiment R&D developments - The 82Se sources production
SuperNEMO baseline with Enriched Selenium I
I
I
82
Se :
3.5 kg from ILIAS European Program (Tomsk facility) 1.0 kg currently being measured in NEMO3 2.0 kg will be bought by JINR Dubna in 2012
Fig.: Enriched
82
Se in a quartz bottle
Purified Selenium I
I
Chemical purification of 1.0 kg natural Se at INEEL (US) Purification by distillation of 1.0 kg 82Se in Russia
Mass Production I
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Possibility to enrich 100 kg 82Se in Russia by centrifugation within the timescale
Fig.: Enriched 40 mg/cm2 SuperNEMO status
82
Se foil 10 / 18
The SuperNEMO experiment R&D developments - Principle of the BiPo detector 232
238
Th
212 60.5 m (65 %) 212
Bi 208
BiPo detector1 214
Po
19.9 m (99.98 %)
299 ns
60.5 m (35 %) 3.1 m 208
U
214
Bi 19.9 m (0.02 %) 1.3 m
Pb 210
Tl
beta
Po
Dedicated detector for qualification of SuperNEMO source background
164.3 µs
210
Pb
Sandwich of a thin source foil between two radiopure plastic scintillators coupled to light-guides and low radioactivity PMTs BiPo decay cascade :
Tl
Scintillator Source
alpha
I t0
Radiopurity requirements :
t 212
BiPo
(t ~ 300 ns)
214
β + delayed α
I
BiPo
(t ~ 164 us) t
I
208
Tl : < 2 µBq/kg Bi : < 10 µBq/kg
214
1 Methods in Physics Research A 622 (2010) 120–128 A. Chapon
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The SuperNEMO experiment R&D developments - BiPo sensitivity
BiPo sensitivity (3.24 m2 ) Surface background measurement : I
I
A(208Tl)BiPo1 ∼ 1.5 µBq/m2 (258 days.m2 @ LSM) 0.6 < A(214Bi)BiPo3 < 23.0 µBq/m2 (5.34 days.m2 @ LSC)
BiPo-3 sensitivity for SuperNEMO I I
82
Se sources :
208
A( Tl) < 2 µBq/kg in 6 months A(214Bi) < 10 µBq/kg in 6 month 18
55
bkg = 5.4 µBq/kg bkg = 1.5 µBq/kg bkg = 0.5 µBq/kg SuperNEMO sensitivity target
16
bkg = 23 µBq/kg bkg = 5.3 µBq/kg bkg = 0.6 µBq/kg SuperNEMO sensitivity target
50
BiPo3 sensitivity − 214Bi (µBq/kg)
BiPo3 sensitivity −
208
Tl (µBq/kg)
45 14 12 10 8 6 4
40 35 30 25 20 15 10
2
5
0
0 0
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4 6 8 duration of measurement (months)
10
12
0
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4 6 8 duration of measurement (months)
10
12
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The SuperNEMO experiment R&D developments - tracker
Tracker Basic 90 cells prototype developed I I
= 44 mm L = 3.7 m
Required performances demonstrated using cosmic muon data σT ∼ 0.7 mm σL ∼ 1 cm Geiger > 98%
Fig.: Robot for automatic wiring
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The SuperNEMO experiment R&D developments - calorimeter
Calorimeter requirements large size detector (scintillator block + 8" PMT) Plastic scintillator : low back-scattering radiopurity PMT : linearity better than 1% between 0 and 3 MeV time resolution of 250 ps at 1 MeV low radioactive background : I I I
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K < 0.1 Bq/kg Bi < 0.04 Bq/kg 208 Tl < 0.003 Bq / kg 214
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The SuperNEMO experiment R&D developments - calorimeter
250
experimental spectrum gaussian fit
N (count/10keV)
200
150
100
50
0 0
0.5
1 Energy (MeV)
1.5
2
Calorimeter Required resolution demonstrated with cubic PVT (256×256 mm2 entrance surface, ≥12cm thick) directly coupled to a 8" PMT (R5912MOD) FWHM = 7.3% @ 1MeV FWHM = 4.2% @ 3MeV
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The SuperNEMO experiment R&D developments
Integration The SuperNEMO demonstrator will be installed @ LSM, after NEMO3 removal The final SuperNEMO detector should be installed in the LSM extension
Fig.: Integration of the SuperNEMO demonstrator @ LSM
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Conclusion Summary
Nemo experiments use "tracking + calorimetry" technique I I I I
Full event reconstruction Clear ββ event signature Excellent background rejection New physics studies1 using event topology (Mass mechanism, RHC, excited states. . . )
SuperNEMO is next generation experiment I I I
I
R&D objectives reached Demonstrator module sensitive to Klapdor claim by 2015 Full detector sensitivity by 2019 : 0ν 82 T1/2 ( Se) > 1 × 1026 yr (hmν (82Se)i < (0.04 - 0.11) eV) Possibility to probe 0ν2β mechanism
BiPo-3 is installing at LSC and should be running before 2012 with required sensitivity for SuperNEMO 82Se sources : I I
A(214Bi) < 10 µBq/kg in 6 month A(208Tl) < 2 µBq/kg in 6 months
1 Eur.Phys.J.C70 :927-943,2010 A. Chapon
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Conclusion Thanks
Thank you for your attention. A. Chapon
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Backgrounds for ββ decays Backup slide
External γ I I
208
Origin : natural radioactivity of the detector or neutrons Main background for 2ν2β but negligible for 0ν2β (100Mo and 82Se : Qββ ≈ 3MeV > Eγ (208Tl) = 2.6MeV)
Tl and
214
Bi contamination inside the ββ source foils
Radon inside the tracking detercor I I
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Deposits on the wires near the ββ foils Deposits on the surface of the ββ foils SuperNEMO status
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Radon trapping facility Backup slide
Radon trapping facility 1 ton of charcoal @ -50o C, 9 bars air flux = 150 m3/h Input : A(222 Rn) 15 Bq/m3 Output : A(222 Rn) < 15 mBq/m3 ! ! ! reduction factor of 1000 Inside the NEMO3 tent : factor of 100 - 300 Inside NEMO3 : almost factor of 10 A(222 Rn) : 6 mBq/m3
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Source production (150 Nd) Backup slide
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Chemical source purification (82Se) Backup slide
Weigh Se Add quartz distilled 6M HNO3 to dissolve Se Heat until dryness Add nanopure H2 O Add quartz distilled 2M HCl Add barium solution Add H2 SO4 , precipitate carries Ra Filter solution Add barium solution Filter solution, improves separation from Ra Add saturated Na2 SO52 , reduce Se to metal which precipitates Let the solution stand Filter Se Combine filtrates and reduce volume, precipitate Se metal Add Se to quartz boats, place boats in furnace, dry Se under He purge Weigh ultra-purified Se Add ultra-purified Se to clean shipping container A. Chapon
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The BiPo detector - BiPo-3 prototype Backup slide
BiPo-3 prototype The BiPo-3 detector (3.24 m2 ) can measure 1.3 kg of SuperNEMO foil (40 mg/cm2 ) with 6.5% efficiency 2 identical modules of 2.7×0.6 m2 each high radiopurity module consists of 18×2 light lines (total 72) I
I
I I I
82
Se
300×300×2 mm3 Polystyrene scintillators [POPOP + pTp] entrance face aluminized with 200 nm of ultra pure aluminum PMMA light guides side reflector in Tyvek (0.2 mm) 5" Hamamatsu R6594-MOD low background PMTs
lead and pure iron shielding, radon free air flushing matacq VME digitizer boards : 2.5 µs @ 1 GHz, 1 V & 12 bit trigger boards for longer delays (214Bi) A. Chapon
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Energy resolution of the calorimeter Backup slide 250
experimental spectrum gaussian fit
N (count/10keV)
200
150
100
50
0 0
0.5
1 Energy (MeV)
18
1.5
2
experimental spectrum 7.96 / sqrt(E)
16
FWHM (%)
14
12
10
8
6
4 0.2
0.4
0.6
0.8
1 1.2 Energy (MeV)
1.4
1.6
1.8
2
PVT cubic block (256×256 mm2 entrance surface) coupled to a R5912MOD PMT
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Probing new physics1 Backup slide
In case of observaton, measure energy difference and cosine of separating angle between electrons to identify mechanism of 0ν2β. Fig.:
pure MM
70% MM + 30 % RHCA admixture
Fig.:
Fig.:
pure RHCA
Combination of half-life measurement (blue contour) and topological parameter reconstruction (green contours) leads to parameter space restriction (red contour) at 1 standard deviation. 1 Eur.Phys.J.C70 :927-943,2010 A. Chapon
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Schedule Backup slide
2010
NEMO3 running
2011
2012
2013
2014
2015
2016
2017
2018
2019
NEMO3 dismantled
SuperNEMO demonstrator commissioning
SuperNEMO demonstrator running 7kg 82Se - T1/2 > 6.5 × 1024 Confirm Klapdor claim ?
full SuperNEMO construction full sensitivity by 2019 mν ≈ 0.05 eV
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