Neutrinoless Double Beta Decay - UW–Madisonmaruyama/talks/Gordon2009... · 2011. 8. 10. · Gordon Conference, July 12-17, 2009 Reina Maruyama P. Vogel, arXiv:hep-ph/0807.2457 (2008)

Reina Maruyama University of Wisconsin, Madison

Gordon Conference, Bryant UniversityJuly 12-17, 2009

Neutrinoless Double Beta DecayAn Experimentalistʼs View

Gordon Conference, July 12-17, 2009 Reina Maruyama

Why double beta decay now?

2

Results from nu-oscillation experiments:• Neutrinos undergo flavor-changing oscillations: possible only if

they have finite masses. • This means that 0νββ is possible (Schechter and Valle, 1982)

Now the Question is...• Why is the mass so small?• How small is it?• Where does it come from?


Implications of an observation of 0νββ0νββ is:• the only practical technique to determine if neutrinos are their own anti-

particles (Majorana particles) • an evidence for lepton number violation. Does Leptogenesis explain the

observed matter/antimatter asymmetry?

An observation of 0νββ:• provides a promising laboratory method for determining the absolute

neutrino mass scale complementary to other neutrino mass measurement techniques.

• observation in multiple isotopes may help reveal the nature of the lepton number violating process(es).

• origins for ν mass and the LNV process(es) can be extracted with reliance on both nuclear and particle theory.

3

If 0νββ is observed ⇒ neurinos are Majorana particle ⇒ lepton number is violated.


Double Beta Decay

4


Double Beta Decay

4

allowed process.

(2νββ): T1/2 ≥ 1018 y


Double Beta Decay

4

allowed process.

(2νββ): T1/2 ≥ 1018 y

2νββ observed for 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 128Te, 130Te, 150Nd


Double Beta Decay

4

allowed process.

(2νββ): T1/2 ≥ 1018 y

Has not been observed. Yet.

(0νββ): T1/2 ≥ 1025 y

2νββ observed for 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 128Te, 130Te, 150Nd


Signature of neutrinoless double beta decay

5

Γ0ν/Γ2ν=1/106

Γ0ν/Γ2ν=1/1002νββ0νββ

2% energy resolution

An Ideal Experiment has... • Low background • High resolution • Large mass• Possibly multiple isotopes‣ ensure peak is not background‣ improve matrix element calcʼs.

• Good detector efficiency • Long running time

a = isotope fractionA = atomic massε = Detector efficiency M = Detector massT = Running timeB = Background (cnts/keV/kg/yr)Γ = Energy resolution

Maximize figure of merit: experimental sensitivity

€

FN ∝εaA

MTBΓ⎡

⎣ ⎢ ⎤

⎦ ⎥

1/ 2


Neutrino Mass and 0νββ Rate

If neutrinos are majorana particles and have majorana mass…

6

0νββ rate:

Effective Majorana mass Phase spaceNuclear matrix elements

Majorana phases

mixing matrixeigen masses


P. Vogel, arXiv:hep-ph/0807.2457 (2008)

Nuclear Matrix Element

7

8x1027

6

4

2

0

0νββ

Ha

lf-lif

e

Ge76 Se82 Zr96 Mo100 Cd116 Te128 Te130 Xe136 Nd150

Rodin nucl-th/0503063

<mββ> = 50 meV

• Meaningful extraction of nu-mass requires theoretical NME uncertainty < 20%

Smaller is better...

• Other considerations for experiments:‣ high Q:

- G ∝ Q5 -> large phase space- less gamma background‣ isotope abundance‣ detector techniques well understood

Effective Majorana mass Phase spaceNuclear matrix elements


Present 0νββ Limits

8

isotope Q-value (keV)

abund. (%) Detector Detection

techniqueT1/20νββ (yr)

90% CL <mββ> (eV)

48Ca 4271 0.187 Elegant IV scintillator > 1.4 x 1022 < 7-45

76Ge 2039 7.8 MPIH/KIAE ionization > 1.9 x 1025 (*) < 0.35 (*)

82Se 2995 9 NEMO3 tracking > 1 x 1023 < 1.8 - 4.9

100Mo 3034 9.6 NEMO3 tracking > 4.6 x 1023 < 0.7 - 2.8

116Cd 2902 7.5 Kiev scintillator > 1.7 x 1023 < 1.7 - ?

128Te 867 31.69 Bernatovitz geochem > 7.7 x 1024 < 0.1 - 4

130Te 2530 33.8 CUORICINO bolometer > 2.94 x 1024 < 0.21 – 0.70

136Xe 2479 8.9 Rome scintillator > 1.2 x 1024 < 1.1 - 2.9

150Nd 3367 5.6 UCI tracking > 1.2 x 1021 < 3 - ?


Present 0νββ Limits

8

isotope Q-value (keV)

abund. (%) Detector Detection

techniqueT1/20νββ (yr)

90% CL <mββ> (eV)

48Ca 4271 0.187 Elegant IV scintillator > 1.4 x 1022 < 7-45

76Ge 2039 7.8 MPIH/KIAE ionization > 1.9 x 1025 (*) < 0.35 (*)

82Se 2995 9 NEMO3 tracking > 1 x 1023 < 1.8 - 4.9

100Mo 3034 9.6 NEMO3 tracking > 4.6 x 1023 < 0.7 - 2.8

116Cd 2902 7.5 Kiev scintillator > 1.7 x 1023 < 1.7 - ?

128Te 867 31.69 Bernatovitz geochem > 7.7 x 1024 < 0.1 - 4

130Te 2530 33.8 CUORICINO bolometer > 2.94 x 1024 < 0.21 – 0.70

136Xe 2479 8.9 Rome scintillator > 1.2 x 1024 < 1.1 - 2.9

150Nd 3367 5.6 UCI tracking > 1.2 x 1021 < 3 - ?


First Observation of 0νββ in 76Ge? 5 detectors of overall 10.96 kg enriched to 86% in the ββ-emitter 76Ge. Most sensitive to date.

T = (0.67 -4.45) x 1025 years (99.73% C.L.)

Majorana ν Mass'' mν= (0.1 - 0.9) eV 99.73% C.L.' mν best = 0.45 eV' '

Heidelberg-Moscow Experiment

Pulse shape selection Klapdor et al., Phys. Lett B 586 (2004)56.66 kg-yr

9


InverseNormal

Limits on ν Masses with DBD

Direct β-decay mass search:mν ≤ 2.2 eV (95% CL)

APS Neutrino Study 2004

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Next generation experiments will probe the inverse hierarchy region


InverseNormal




10


Disfavored by cosmology +KATRIN sensitivity


InverseNormal




10


cuoricino exclusion (w/ NME uncertainty)



InverseNormal




Possible 0νββ Evidence Klapdor et al., Phys. Lett B 586 (2004) 198 ! (0.67 – 4.45) x 1025 yrs ' (0.1 – 0.9) eV' mνbest = 0.45 eV

10


cuoricino exclusion (w/ NME uncertainty)



Overview of Experiments

11

CUORE/Cuoricino


main candidate isotope: 130Te Q-value: 2530 keV Isotopic abundance: 34%

For E = 1 MeV: ΔT = E/C ≅ 0.1 mK Signal size: 1 mV

Time constant: τ = C/G = 0.5 s Energy resolution: ~ 5-10 keV at 2.5 MeV

Heat sink: Cu structure (8-10 mK)Thermal coupling: Teflon (G = 4 pW/mK)Thermometer: NTD Ge-thermistor (100 kΩ/µK)Absorber: TeO2 crystal (C ≅ 2 nJ/K ≅ 1 MeV / 0.1 mK)

TeO2 Bolometer: Source = Detector

CUORE/Cuoricino Bolometer

Single pulse example

Time (ms)

Am

plitu

de (a

.u.)

1000 2000 3000 4000

13

5 cm

790g per crystal deposited energy


Total detector mass: 40.7 kg ⇒ 11.64 kg 130Te

Cuoricino

11 modules, 4 detector each,crystal dimension: 5x5x5 cm3

crystal mass: 790 g44 x 0.79 = 34.76 kg of TeO2

2 modules x 9 crystals eachcrystal dimension: 3x3x6 cm3

crystal mass: 330 g9 x 2 x 0.33 = 5.94 kg of TeO2' (2 enriched in 128Te @82.3%)' (2 enriched in 130Te @75%)

Shielding:• Cu box + Roman Pb inside cryostat• 20 cm Pb & 10 cm borated polyethylene outside

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Gordon Conference, July 12-17, 2009 Reina Maruyama 15

Cuoricino:44 5x5x5 cm3

and 18 3x3x6 cm3

TeO2 crystals

detector mass 40.7 kg; 130Te mass 11 kg

CUORE:988 5x5x5 cm3 TeO2 crystals

detector mass ~750 kg;130Te mass ~200 kg

Cuoricino as prototype

Cuoricino to CUORE


CUORICINO Results

16

CUORICINO was stopped in June 2008Arnaboldi et al. PRC 78, 035502 (2008)

Statistics18 kg•yr of 130Te

Mass boundsmee < 0.18 – 0.91 eV

Background0.18 +/- 0.01 c/keV/kg/yr

Resolution8 keV (FWHM)

T1/20ν (130Te) > 2.94 x 1024 y @ 90% C.L. (Prelimary)


CUORE

Improvements over Cuoricino x19 mass, closely packed‣ Better self-shielding & anti-coincidence cut‣ Improved cryostat, trigger & daq for better

efficiency x20 reduction in background ‣ Stringent shielding, material selection and

controlled handling x1.5 improvement in resolution‣ More uniform construction & assembly

no isotope enrichment

Goalbackground < 0.01 cnts/keV/kg/y

Resolution = 5 keV5 year sensitivityF0ν > 2.1 x1026 y

mee < ~ 25 – 130 meV

17

APS Neutrino Study

KKDC

CUORE


<mββ> to T1/2 0ν(130Te) via matrix elements

Assuming KKDC mass Assume 19<|mν|<50 meV

18



Assuming KKDC mass Assume 19<|mν|<50 meVCuoricino limit

18



Assuming KKDC mass Assume 19<|mν|<50 meVCuoricino limit

18

CUORE


Two dilution refrigerators:Hall A: CUORICINO

CUORE: next to Cuoricino Hall C (R&D final tests for CUORE)

Gran Sasso National Underground Laboratory

Overburden at LNGS: 3200 m.w.e

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19

June 2008






19

June 2008

May 2009


Study of background in CUORICINO

Study of origin of α in Cuoricino with Hall C & Monte Carlo• < 2.6 MeV: Higher rates due to higher γ rates in Hall C cryostat than in Cuoricino.

Possible to study α backgrounds only.• > 3 MeV: Significant reduction shown• Tested items: cleaning procedures, mounting schemes, structure design, material

selections• Factor of 4 reduction seen in crystal surface contamination, ~2 in Cu surfaces• More studies underway to reach goal of < 0.01 c/keV/kg/yr, including the effect of anti-

coincidence, pulse-shape analysis, etc.

CuoricinoHall C

Comparison of Cuoricino and Hall C measurements

20


Background Gammas• Sons and daughters of 238U (214Pb, 214Bi, 210P, etc)• 232Th-chain (212Pb, 228Ac, 208Tl, 212Bi)• Cosmogenic activtion of Copper: 60Co, 54Mn• Fall out isotopes: 137Cs, 207Bi• All except 208Tl @ 2615 keV are below Q-value = 2530 keV

21


Cuoricino Background in the 0νββ Region

40 ± 10% from 208Tl (2615 keV) from Th in cryostat shields 10 ± 5% from αʻs from U/Th on crystal surfaces50 ± 20% from αʻs from U/Th, mainly from copper surfaces

214Bi 0νββFlat b.g. from α’s

Cuoricino background (2520 - 2590 keV): 0.18 ± 0.01 cnts/(keV-kg-y)

22


Materials Certification for Crystal Production

23

se_1622-1648-gr1-xyEntries 16000Mean 3644RMS 2411

energy (keV)0 2000 4000 6000 8000 10000 12000 14000 16000

coun

ts/(1

keV

)

1

10

210

310

410

510 se_1622-1648-gr1-xyEntries 16000Mean 3644RMS 2411

se_1622-1648-gr1-xy


Background levels in all neary-by materials were measured by HPGe, silicon barrier detector, R&D bolometer setup in Hall C, ICPMS, neutron activation analysis etc., compared with CUORICINO, and extended to CUORE Monte Carlo.

Expected Backgrounds in CUORE

Source Expected background (cnts/keV/kg/yr)

Outside inner Pb shield (environmental, cryostat, induced nʼs…)

< 10-3

Internal Pb shield & Cu structure bulk < 10-3

Small parts (NTD Ge, PTFE, Au wires…) < 10-3

Inert surfaces (e.g. Cu structure, shields) ~ (2-4) x 10-2

TeO2 Bulk (Hall C: measurement) < 10-4

TeO2 Surface (Hall C: measurement) < 3 x 10-3

2νββ ~ 10-4

24


Crystal Production and verification

– Metal and oxides for TeO2 tested for radio purity before production

– Polishing and lapping compounds also tested.

– Verification in Hall C cryostat to test

– subset of crystals flown for bolometer performance and contamination certification‣ Bulk: < 10-13 g/g 238U and

232Th‣ Surface: < 10-8 Bq/cm2

– Shipped by boat to avoid activation by cosmic ray


CUORE Detector Calibration System

26

place sources next to crystals to allow calibration of all bolometers

→ individual energy calibration of all 988 bolometers critical for summing energy spectra



26

vertical cross section of the cryostat

Pb shield

300K

40K

4K

0.7K

80mK

10mK

detectors@ ~10mK

Pb shield





26


Pb shield

300K

40K

4K

0.7K

80mK

10mK

detectors@ ~10mK

Pb shield

motion system:insertion and extraction of sources in and out of cryostat





26


Pb shield

300K

40K

4K

0.7K

80mK

10mK

detectors@ ~10mK

Pb shield



guide tubes: no straight vertical accesssource strings:move under own weight in guide tubes




26


Pb shield

300K

40K

4K

0.7K

80mK

10mK

detectors@ ~10mK

Pb shield



guide tubes: no straight vertical accesssource strings:move under own weight in guide tubes

top view of detector array with source positions

source locations



Source Carriers

active region: ~85 cm (the detector region when fully

deployed)

non-active region: ~3 or 4 m (from motion

box to detectors)

Kevlar string

dia: 0.35 mm

4:1 PTFE heat shrinkthickness: 0.1 mm

crimp cross-section

~ 9.2 mm

8 mm

~1.5 mm

1.59 mm 0.88 mm

active source

4 K thermalization

point


Final ChecksHall-A (cuoricino cryostat)

– Three-tower test in Cuoricino Cryostat• 3 x 12 = 36 crystals• Tests three copper cleaning procedures• Gain more statistics for performance of new geometry for

NTD thermistors– CUORE-0

• “First-tower” of CUORE (52 crystals)• Materials verification• Test assembly automation and procedures• Data acquisition, processing

Hall-C R&D Cryostat– Crystal production validation

• Bulk contamination in the crystal (intrinsic and activated)• Surface contamination from polishing, lapping, and

handling28

the main shake and aftershocks as seen by

the large-scale R&D detector running in the Cuoricino cryostat (the

final test of copper cleaning procedures)

Estimated delay of up to 6 months




Estimated delay of up to 6 monthsinitial quake




Estimated delay of up to 6 months




Estimated delay of up to 6 monthsaftershocks


18

If Ge claim (KKDC) is correct CUORE would see (five years):


18

If Ge claim (KKDC) is correct CUORE would see (five years):

University of California at BerkeleyA. Bryant2, M.P. Decowski2 , M.J. Dolinski3 , S.J. Freedman2,

E.E. Haller2, L. Kogler2, Yu.G. Kolomensky2

University of South CarolinaF.T. Avignone III, I. Bandac, R. J. Creswick, H.A. Farach,

C. Martinez, L. Mizouni, C. Rosenfeld Lawrence Berkeley National Laboratory

J. Beeman, E. Guardincerri, R.W. Kadel, A.R. Smith, N. Xu Lawrence Livermore National Laboratory

K. Kazkaz, E.B. Norman4, N. ScielzoUniversity of California, Los Angeles

H. Z. Huang, S. Trentalange, C. Whitten Jr. University of Wisconsin, Madison

L.M. Ejzak, K.M. Heeger, R.H. Maruyama, S. SangiorgioCalifornia Polytechnic State University

T.D. Gutierrez

2also LBNL3also LLNL

4also UC Berkeley

Universita’ di Milano-Bicocca5

C. Arnaboldi, C. Brofferio, S. Capelli, M. Carrettoni, M. Clemenza, E. Fiorini, S. Kraft, C. Maiano, C. Nones, A. Nucciotti, M. Pavan,

D. Schaeffer, M. Sisti, L. Zanotti Sezione di Milano dell’INFN

F. Alessandria, L. Carbone, O. Cremonesi, L. Gironi, G. Pessina, S. Pirro, E. Previtali

Politecnico di MilanoR. Ardito, G. Maier

Laboratori Nazionali del Gran Sasso M. Balata, C. Bucci, P. Gorla, S. Nisi, E. L. Tatananni, C. Tomei, C. Zarra

Universita’ di Firenze and Sezione di Firenze dell’INFNM. Barucci, L. Risegari, G. Ventura

Universita’ dell’Insubria5

E. Andreotti, L. Foggetta, A. Giuliani, M. Pedretti, C. SalvioniUniversita di Genova

S. Didomizio6, A. Giachero7, P. Ottonello6, M. Pallavicini6 Laboratori Nazionali di Legnaro

G. Keppel, P. Menegatti, V. Palmieri, V. Rampazzo Universita di Roma La Sapienza and Sezione di Roma dell’INFNF. Bellini, C. Cosmelli, I. Dafinei, R. Faccini, F. Ferroni, C. Gargiulo,

E. Longo, S. Morganti, M. Olcese, M. Vignati Universita’ di Bologna and Sezione di Bologna dell’INFN

M. M. Deninno, N. Moggi, F. Rimondi, S. ZucchelliUniversity of Zaragoza

M. MartinezKammerling Onnes Laboratory, Leiden University

A. de Waard, G. FrossatiShanghai Institute of Applied Physics (Chinese

Academy of Sciences)X. Cai, D. Fang, Y. Ma, W. Tian, H. Wang

5also Sezione di Milano dellʼINFN6also Sezione di Genova dellʼINFN

7also LNGS

CUORE collaborators


19

Scientific Reach of Existing 0νββ Experiments

CUORICINO

With most favorable matrix element


First Shipment of Crystals in Gran Sasso!

33


CUORE Sensitivity

8

6

4

2

0

T 1/20ν

Sen

sitiv

ity [1

026 y

ears

]

1086420Running Time [years]

CUORE (bkgd = 0.001 cnts/keV*kg*yr) CUORE (bkgd = 0.01 cnts/keV*kg*yr)

5 yr sensitivity = 6.5 x 1026 yrs

5 yr sensitivity = 2.1 x 1026 yrs

Projected sensitivity of CUORE (1σ)400

300

200

100

0<m

ν> [m

eV]

1086420Running Time [years]

CUORE bgd = 0.01 cnts/keV*kg*yr CUORE bgd = 0.001 cnts/keV*kg*yr

<mν> sensitivity from QRPA Calculations

* <m> range from various QRPA calculations:" high: Rodin, Faessler, Simkovic, & Vogel Nucl. Phys. A 766 107 (2006)" low: Staudt, Kuo & Klapdor-Kleingrothaus, PRC 46 871 (1992)

34


In case of discovery, cross-checks are critical:- check background lines, nuclear models and matrix elements- reduce systematic uncertainty on〈mββ〉

Beyond CUORE: Future Opportunities



advanced bolometers fast surface events

slow bulk events

pulse

am

plitu

de o

n G

epulse amplitude on TeO2



other isotopes

Already tested bolometrically,as good as TeO2CaF2, Ge, PbMoO4, CdWO4

35



slow bulk events

pulse

am

plitu

de o

n G




other isotopes

Already tested bolometrically,as good as TeO2CaF2, Ge, PbMoO4, CdWO4

35



slow bulk events

pulse

am

plitu

de o

n G


isotopic enrichment of 130Te

- up to 3x more sensitive- no change for CUORE experimental infrastructure needed



Gamma region, dominated by gamma and beta events, highest gamma line = 2615 keV 208Tl line (from 232Th chain)

Alpha region, dominated by alpha peaks(internal or surface contaminations)Eint = Eα + Erec Esurf = Eα - Δ

36

CUORICINO Background


Num

ber o

f det

ecto

rs

CUORE Detector Energy Resolution

Best 5x5x5 cm3 crystal (R&D in hall C)0.8 keV FWHM @ 46 keV1.4 keV FWHM @ 351 keV2.1 keV FWHM @ 911 keV2.6 keV FWHM @ 2615 keV (.1%)3.2 keV FWHM @ 5407 keV

CUORE Goal: 5 keV FWHM @ 2500 keVLimiting factor in Cuoricino:• stability of cryostat • thermal couplingCUORICINO Crystals• best: 3.9 keV @ 2615 keV• Average: 8 keV• 5x5x5 cm3 average: 7 keVR&D test • 10 crystals, 5x5x5 cm3: 5.7 keVImprovements:• Production of uniform thermistors• new thermistor geometry for easy/uniform

bonding• Uniform thermal coupling of crystal to thermistor• Better design of crystal holders• Improved gain stabilization through heater pulses

CUORICINOHall C test

37


Calibration of Cuoricino/CUORE Bolometers

38

Gain StabilizationFor each bolometer an energy pulse generated by a Si resistor is used to correct pulse amplitudes for gain instabilities (→ every 5 min).

Voltage-Energy ConversionFit of a calibration measurement with a gamma source (e.g. 232Th). Energy calibration performed regularly. (~ monthly).

Cuoricino calibration


Calibration of Cuoricino/CUORE Bolometers

38

Gain StabilizationFor each bolometer an energy pulse generated by a Si resistor is used to correct pulse amplitudes for gain instabilities (→ every 5 min).

Voltage-Energy ConversionFit of a calibration measurement with a gamma source (e.g. 232Th). Energy calibration performed regularly. (~ monthly).

Cuoricino calibrationCuoricino summed spectrum from all detectors



39

radioactive source wire• 56Co: proton activated Fe wire• 232Th: Thoriated Tungsten wire

Kevlar string

Cu crimp

PTFE heat shrink

source wire• flexible, moves in guide

tube under own weight

• small mass: < 5 grams

• vertical distribution of source activity can be adjusted

Source String

Guide Tubes• stainless and/or machined from solid, low-background copper

~1m

~10mm


Calibration Source Simulations

40

Optimization of Source Strength, Position, and Distribution

Activity per discrete source:– internal/external sources: 87 mBq/430 mBq

– internal/external sources edges: 126 mBq/1010 mBq

Max hit rate of 100mHz per crystal to avoid pile-up, based on Cuoricino experience

event rate in crystals

layer 5

source positions

• achieve uniform illumination of all crystals with internal/external sources

• determine max source activity, minimize calibration time

external sourcesinternal sources


Calibration Source Simulations

41

radioactive sources: 56Co and/or 232Th

56Co: proton activated Fe wire; 232Th: Thoriated Tungsten wire

both have been used in Cuoricino

Calibration time vs counts in peak

~100 events over background per peak are required for successful calibration


NEMO-3

• Tracking detector:– drift wire chamber in Geiger

mode• Calorimeter:

– 1940 plastic scintillators w/ low background PMTs

• Source: 10 kg of sources– 0νββ: 6.9 kg of 100Mo, 0.9 kg

82Se– 2νββ: 10 - 500g of 116Cd, 96Zr,

150Nd, 48Ca, 130Te

42PRL95,182302(2005)

Documents

Neutrinoless Double Beta Decay - UW–Madisonmaruyama/talks/Gordon2009... · 2011. 8. 10. · Gordon Conference, July 12-17, 2009 Reina Maruyama P. Vogel, arXiv:hep-ph/0807.2457 (2008)