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Double beta search : experimental view. Laurent SIMARD, LAL - Orsay. 6 th Rencontres du Vietnam, Hanoi, 6 th -12 nd August 2006. W -. n eR. h. n eL. h. ( ). D L = 2 Process Majorana Neutrino n = n and effective mass Right-handed current in weak interaction - PowerPoint PPT Presentation
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Double beta search : experimental view
Laurent SIMARD, LAL - Orsay
6th Rencontres du Vietnam, Hanoi, 6th-12nd August 2006
(0) : 2n 2p+2e-
L = 2 Process Majorana Neutrino and effective mass
<m>
Right-handed current in weak interaction
Majoron emission
SUSY particle exchangeWn
n
p
p
e
e
M
(Q ~ MeV)
( )T0
2/1
W
eR
eL
h
h
Double beta Double beta (0(0) decay:) decay:
Physics beyond the standard modelPhysics beyond the standard model
A=<m> xPSx IM I2 2
Nuc.
Both techniques are complementaryand at least 2 or 3 experiments are needed
to really prove the 0 decay at a level of 5
Modest energy resolution and efficiency Large detector a few 10 m
No signature of the 2 electrons Only 1 observable: total energy
Very high energy resolutionGood efficiency« Compact » detectors (size 10 m)Crystals very pure (surface contamination ?)
Direct signature of the 2 electrons3 observables: - total deposited energy
- individual energy - angular corelation
Possibility to measure various isotopes
Experimental approachesExperimental approaches
Calorimeter
HPGe, Cd – Te bolometers
Tracking + calorimeter
NEMO,EXO
PURE CALORIMETER
The GERDA project (LNGS)
- operate with “naked” Ge diodes in a very pure liquid nitrogen shielding (LN2)- possible upgrade with liquid argon(LAr) for active anticoincidence from the scintillation light of LAr- segmentation of diodes for a greater reduction of backgrounds
The MAJORANA Project in the US210 HPGe segmented diodes in a standard shielding
(500 kg of enriched 76Ge)
Phase III ~ 100 kgSegmented crystalsLiquid Argon 10 years of data-taking
Phase III
10-1 /(keV·kg·y) 10-2 /(keV·kg·y) 10-3 /(keV·kg·y)
Phase I ~ 15 kg 76Ge (crystalsHeidelberg-Moscow + IGEX)
Phase I
(2008)
Phase II ~ 35 kg 76GeSegmented crystals3 years of data-taking
Phase II
(2010)
start with 60 kg
New detectors for Phase II:Procurement of enriched Ge
March ’05: procurement of 15 kg of natural Ge (‘test run’)
Sep ’05: enrichment of 37.5 kg of Ge-76 completed ! ~ 88% Ge-76
April ’06: enriched material transported to Germany; now stored underground at HADES
Specially designed protective steel container reduces activation by cosmic rays by factor 20
Backgrounds in GERDA
Source B [10-3 cts/(keV kg y)]
Ext. from 208Tl (232Th) <1
Ext. neutrons <0.05
Ext. muons (veto) <0.2
Int. 68Ge (t1/2= 270 d) 12
Int. 60Co (t1/2= 5.27 y) 2.5
222Rn in LN/LAr <0.2
208Tl, 238U in holder <1
Surface contam. <0.6
180 days exposure after enrichment + 180 days underground storage
30 days exposure after crystal growing
Target for phase II: B 10-3 cts/(keV kg y) additional bgd. reduction techniques
derived from measurements and MC simulations
Muon veto
Background reduction techniques
• Muon veto
• Anti-coincidence between detectors
• Segmentation of readout electrodes (Phase II)
• Pulse shape analysis (Phase I+II)
• Coincidence in decay chain (Ge-68)
• Scintillation light detection (LArGe)
130Te
Goal: () of 130Te
~ 1000 TeO2 bolometers
Q ~ 2.5 MeV
Experimental data and simulations suggest one major contribute for CUORE background in the DBD region:
and degraded particles emitted by 238U and 232Th surface contaminations on the Cu frame and
on the crystal surface.
BKG = 0.18 ± 0.01 c/(keV kg y)
T1/2 > 2×1024 y @ 90% C.L.
Cuoricino
130Te
TeO2
Cu
TeO2
CUORE : 130Te in LNGS (760 kg of Te)
If background = 0.01 cps/ (keV.kg.year) T1/2() 2.1 x 1026 years (90% C.L.)
If background = 0.001 cps/ (keV.kg.year) T1/2() 6.6 x 1026 years (90% C.L.)
If background = 0.001 cps/ (keV.kg.year) + enriched crystals T1/2() 1.9 x 1027 years (90% C.L.)
After 5 years of data takingFWHM = 5 keV @ 2528 keV
Predictions on the future background expected for CUORE from Cuoricino background analysis and Monte Carlo simulations...
Surface Sensitive BolometersSurface Sensitive Bolometers
Background reduction may be achieved through both passive
and active methods
Creation of a new kind of detectors able to recognize surface events
Identification of background events
Surface
Sensitive
Bolometers
Auxiliary bolometer Main bolometer
SSB
Classic pulse
Classic pulse
Classic pulse
High and fast pulse
Dynamic behavior:
Event originating inside the main bolometer (DBD event)
Event originating outside the main bolometer (degraded )
The difference between heat capacities generates a difference
in pulse height and shape...
Idea: cover each face of a classic bolometer by gluing an active layer, in order to provide a 4 shielding
First SSB experimental results (Como)First SSB experimental results (Como)
Amplitude comparison
According to the described dynamic behavior, various pulse parameters proved to be effective in discriminating surface events.
(Scatter plot)
-Individual thermistor read-out-Parallel thermistors read-out
r on auxiliary thermistor
Bulk events
Surface events
Pul
se a
mp
litu
de
on
aux
ilia
ry N
TD
[m
V]
Pulse amplitude on main NTD [mV]
d on main thermistor
Surface events
Bulk events
Pulse amplitude on main NTD [mV]
Pul
se a
mp
litu
de
on
aux
ilia
ry N
TD
[m
V]
(To be investigated)
14. OUTGASSING
15. REACTIVE CLEANING: Anodic Oxidation and subsequent removal of the oxide16. OZONE CLEANING17. HYDROGEN CLEANING
1. ABRASIVE CLEANING, GRINDING and MECHANICAL POLISHING
2. SOLVENT CLEANING: Chlorofluorocarbons and Liquid CO2 3. SEMI-AQUEOUS CLEANERS: Terpenes; Alcohols; Ketones; Esters; Amines4. ULTRASONIC CLEANING5. MEGASONIC CLEANING6. SAPONIFIERS, SOAPS, AND DETERGENTS7. WIPE-CLEAN8. SUPERCRITICAL FLUIDS
9. CHEMICAL ETCHING10. ELECTROCHEMICAL POLISHING11. ELECTROLESS ELECTROLYTIC CLEANING12. DEBURRING: laser vaporization, thermal pulse flash deburring13. STRIPPABLE COATINGS
18. REACTIVE PLASMA CLEANING AND ETCHING19. PLASMA CLEANING20. SPUTTER CLEANING21. ION BEAM CLEANING
THE POLISHING SYSTEM
The CANDLE project
Prototype CANDLE III is in constructionOsaka-JAPAN
•Pure CaF2 crystals 103 cm3 (scintillation)
• Energy resolution: ~ 5% @ 4.2 MeV
• CANDLES III: 60 crystals : Total mass = 191 kg Crystals natural Calcium
~ 300 g of 48Ca
Technique could be very promising with enriched 48Ca crystals Need to enrich ~ 100-200 kg of 48Ca !...
TRACKING + CALORIMETER
THE EXO PROJECTTPC with Xenon : possibility to use a large mass of isotope
Xe noble gaz : centrifugation -> 200 kg of 130Xe avalaible in Stanford T½ very high
Identification of Ba ion : 136Xe 136Ba++ +2e-
by laser fluoresence
Difficulty: neutralisation Ba++ Ba+
collection of ions
Phase 1: EXO-200, 200 kg of 136XeTPC with liquid Xe, detection of scintillation (FWHM ~ 2% @ 2.5 MeV)No identification of the Ba+ ion Start foreseen end 2007Expected background : 0.003 cts.keV-1.kg-1.y-1
T½ > 3 1025 y
With identification of the Ba+ ion and 1 ton of 136XeExpected background < 0.0005 cts.keV-1.kg-1.y-1
Date ? T½ > 1027 years
3 m
4 m
B (25 G)
20 secteursSource: 10 kg of isotopes cylindrical shape, S = 20 m2, e ~ 60 mg/cm2
Tracking detector: wire chamber in Geiger regime (6180 cells)Gas: He + 4% ethylic alcohol + 1% Ar + 0.1% H2O
Calorimeter: 1940 plastic scintillators coupled to low-radioactivity PMTs
Magnetic field : 25 GaussGamma shielding : Iron (e = 18 cm)Neutron shielding : 30 cm water (ext. wall)
40 cm wood (top and bottom) (since march 2004: borated water)
Able to identify e, e, et
The NEMO3 detectorFrejus Underground Laboratory (LSM) : 4800 m equivalent
water
82Se
Preliminary results of NEMO-3Phase I (with radon) February 2003 - September 2004 : 298 days of data taking
Phase II (without radon) December 2004 - March 2006 : 290 days of data taking 100Mo, 7 kg 82Se, 1 kg
T1/2() > 5.8 1023 (90 % C.L.) T1/2() > 2.1 1023 (90 % C.L.)
T1/2() > 2 1024 (90 % C.L.) T1/2() > 8 1023 (90 % C.L.)Expected in 2009
Phases 1+2
NEMO-3 SuperNEMO
T1/2() > ln2 M Tobs
Nexcluded
Navo
A
7 kg 100 kg Isotope mass M
Efficiency () = 8 % () = 25 %
~ 2 evts / 7 kg / y ~ 1 evt / 100 kg/ y
BackgroundInternal contaminations
208Tl and 214Bi in the foil
214Bi < 300 Bq/kg208Tl < Bq/kg
214Bi < 10 Bq/kg208Tl < Bq/kg
(208Tl, 214Bi) ~ 1 evt/ 100 kg /y(208Tl, 214Bi) ~ 1 evt/ 7 kg /y
T1/2() > 2. 1024 y<m> < 0.3 – 1.3 eV
T1/2() > 1026 y<m> < 0.05 – 0.1 eV
SENSITIVITY
FWHM(calo)=8% @3MeV FWHM(calo)=4% @3MeVEnergy resolution
From NEMO-3 to SuperNEMO
Shielding :Water aganist and neutron Source foil
5,7 m
13 m
4 m
New cavity ~ 70m x 15m x15m
~ 2 000 tons of water for 20 modules
View of the detector in its shielding
• 2009-2010: construction of the 1st module
• 2010: commissioning of the 1st module measurement of the background level• 2010 – 201N: construction of the other
modules• 201N: full detector
Which isotope for SuperNEMO ?
• High phase space factor
• Favorable nuclear matrix element… but uncertain calculations…
• High Q for the background rejection
• Possibility of enrichment !...
Choice criteria for the isotope:
Phase space factorNuclear matrix element
Uncertainties from the theoretical calculations
Effective mass of the Majorana neutrino
= G M ‹m›22
T1/2
1
Half-life of the decay
Which isotope for SuperNEMO ?
Isotope Q (MeV) G (an-1) Shell Model
QRPA
48Ca 4.271 2.44 9.2 1026 2.9 1027
76Ge 2.040 0.24 7 1027 2.4 1027
82Se 2.995 1.08 9.6 1026 7.4 1026
96Zr 3.350 2.24 1.5 1028
100Mo 3.034 1.75 1.4 1027
116Cd 2.802 1.89 1027
130Te 2.528 1.70 3.6 1026 1027
136Xe 2.479 1.81 5.2 1026 2-5 1027
150Nd 3.367 8.00 1.2 1026
T1/2() with m=50meV
With QRPA nuclear matrix elements calculations,100 kg of 150Nd is equivalent to: ~ 340 kg of 82Se ~ 720 kg of 130Te ~ 1010 kg of 76Ge ~ 2640 kg of 136XeBut value of MM00 22 ? ?Shell Model: Caurier et al.
QRPA: Faesller Rodin Simkovic Vogel 2005
Only phase space factor(M=1)100 kg of 150Nd is equivalent to: ~ 410 kg of 82Se ~ 410 kg of 130Te ~ 1700 kg of 76Ge ~ 400 kg of 136Xe
Enrichment of isotopes
82Se: 100 kg in 3 years in ECP Zelenogorsk (Siberia) price ~ 50 keuros / kgAgreement for 1.5 kg (ILIAS funding)
Enrichment by centrifugation:
• SILVA Infrastructure in Pierrelate (France)• In 2003: enrichment of 200 kg of 235U in 2 weeks !
235U + 3 photons 235U+ + e
• Possibility of enrichment of 200 kg of 150Nd in few weeks ! Simulations done par Alain Petit (DEM, CEA) • Enrichment of 96Zr and of 48Ca could be considered : to be studied…
• Main goal : maintain the installation for an enrichment of 100 kg of 150Nd “Statement” of the SuperNEMO collaboration
Enrichment by laser photoionisation
Sensibility of SuperNEMO : discussionSensibility of SuperNEMO : discussion
Simulation Monte Carlo with 5 years of data taking 82Se T1/2 > 1026 years
mais constrain on 214Bi, Radon et 208Tl are very strong
150Nd T1/2 > 6 1025 years equivalent to 5 1026 y (82Se) because of the phase space factor. background similar for 82Se whereas T1/2 is lower
(Fermi factor : coulombian effect due to the high Z) No constraint on 214Bi and radon (Q = 3.367 MeV)
48Ca T1/2 1.5 1026 years equivalent to 5 1026 y (82Se) because of the phase space factor. No constrain on 214Bi and radon Constrain on 208Tl much less stronger (Q = 4.271 MeV)
150Nd: T1/2() = 1019 y82Se: T1/2() = 1020 y
Experiment Nucleus Mass(kg)
FWHM atQ (keV)
BackgroundCounts/
fwhm.kg.y
T1/2()
limit(years)
<m> limit
(meV)
Startingtakingdata
NEMO 3
CUORICINO
100Mo82Se
130Te
71
10
350350
7
~ 0.5~ 0.1
~ 0.2
2. 1024
8. 1023
4. 1024
300 - 1300600 – 1700
250 – 850
GERDA Phase 1 Phase 2 Phase 3
76Ge 1535
300
444
0.040.0040.004
3. 1025
2. 1026
6. 1027
250 – 780100 – 290
20 – 55
2008??
SuperNEMO 82Se 150Nd
100 210 0.01 1. 1026
6. 1025
45 – 13070
20122012
CUORE
if enrichmt 130Te
natTenatTe130Te
200200700
555
0.050.0050.005
2. 1026
6.6 1026
2. 1027
35 – 120 20 – 65
2012??
CANDLES IIIif enrichmt 48Ca
natCa48Ca
0.2200
200200 0.1 4 1026 30 – 100
2007?
EXO-200EXO Ba+ tag
136Xe 1601000
5050
0.950.025
3. 1025
1027
90 – 55015 – 95
2007?
Nuclear Matrice elements: Shell Model: Caurier (2004) private com. Stoica et al. (2001) Suhonen et al. (1998 and 2003) QRPA Rodin, Simkovic, Faessler (2005)
Expected sensitivities
COBRA 116Cd 418 <56 <0.001 ~1026 ?~ 60-180
Constrain on <m>
Cosm
ology
Cosm
ology
Current experiments Current experiments
Next generation Next generation
(Figure from C. Giunti)
Cuoricino and NEMO3 are running ~ for 5 years : range ≈ a few 100 meV
R&D for new experiments with a mass of ≈ 100 kg of enriched isotopes.
aim : a few 10 meV with at least 3 isotopes
Coordination in Europe (ILIAS)
Neutrinoless double beta decay could be one of the experimental key for understanding neutrino physics : it is a long way but promising ?
ConclusionConclusion
Radon in the NEMO-3 gas of the wire chamber
Due to a tiny diffusion of the radon of the laboratory inside the detector A(Radon) in the lab ~15 Bq/m3
222Rn (3.8 days)
218Po
214Pb
214Bi
214Po
210Pb
s
~ 1 -like events/year/kg with 2.8 < E1+E2 < 3.2 MeV
Two independent measurements of radon in NEMO-3 gas
Good agreement between the two measurements
Radon detector at the input/output of the NEMO-3 gas
~ 20 counts/day for 20 mBq/ m3
(1e + 1 ) channel in the NEMO-3 data:Delayed tracks (<700 s) to tag delayed from 214Po
214Bi 214Po (164 s) 210Pb
~ 200 counts/hour for 20 mBq/m3
A(Radon) in NEMO-3 20-30 mBq/m3
Decay in gas
delayed
214Bi 214Po (164 s) 210Pb
Radon was the dominant backgroundRadon was the dominant background
for for 00 search in NEMO-3 search in NEMO-3
May 2004 : Tent surrounding the detector
Free-Radon Purification System 1/2Free-Radon Purification System 1/2
Starts running Oct. 4th 2004 in Modane Underground Lab.
1 ton charcoal @ -50oC, 7 bars
Activity: A(222Rn) < 15 mBq/m3 !!!Flux: 125 m3/h a factor 1000
Free-Radon Air Free-Radon Air factoryfactory
5.8 11.6 17.4 23.1 Time (days)
Level of radon measured inside the wire chamber, by analysing (1e + 1 ) channel in the NEMO-3 data
Without tent: A ~ 1.5 Bq
After flushing radon-free air inside the tent: A ~ 0.15 Bq
Radon level reduced by a factor of 10
Residual level to
be understood
sources ?
Thanks a lot to S.K especially M.Nakahata,S.Tasaka
Radon level inside the detectorRadon level inside the detector
- Results -- Results -
The double beta process
Allowed process2
if m0 and
double beta 0
Q: end-point energy ~ 2-4 MeV
Experimentally : a peak forThe energy sum of the 2 e-
Arbitrary
scale
E/Q
Two different approachesPURE CALORIMETER
• only measurement ofthe energy sum of the 2 e-
Esum• high efficiency• high precision for the
measurement of EsumBUT
• sensitive to an unknown gamma line
Semi-conductors : GERDA,MAJORANA (Ge)
CANDLE (Cd,Te)Bolometer :
CUORICINO/CUORE
TRACKING+CALORIMETER• identification of the 2 e-
• measurement of the 2 electrons energies, and of the angular distribution
• measurement of each background amount
BUT• reduced efficiency andenergy resolution
NEMO/SuperNEMO, EXO
IDENTIFICATION OF THE NATURE OF THE PROCESS(Majorana , right current…)
GERDA : 76Ge in LNGS
Vacuum insulated Copper or steel vessel
Water tank / buffer/ muon veto
Liquid N/Ar
Ge Array
Phase I :17.9 kg of enriched
Ge-detectors underground at LNGS
(from IGEX and Heidelberg-Moscow)
HdM
IGEX