IOP HEPP 2009 1Matthew Kauer

Double beta decay of Zr96 using NEMO-3 and calorimeter R&D for

SuperNEMO

IOP HEPP 200908 April

Matthew KauerUCL London

IOP HEPP 2009 2Matthew Kauer

Theory and motivation

Phase space Nuclear matrix element

ve effective massHalf-life

2vbb• allowed in Standard Model (SM)• input to 2vbb nuclear matrix element (NME) calculations• useful for 0vbb NME calculations• key background to 0vbb (irreducible)

0vbb• beyond SM: x2 total lepton number violation• most sensitive way to establish Majorana/Dirac nature of neutrino• most sensitive way to measure absolute v mass in a lab environment (for Majorana v’s)• possible access to v mass hierarchy and Majorana CP-violation phases• link to matter-antimatter asymmetry (leptogenesis)

Insert new

physics here

IOP HEPP 2009 3Matthew Kauer

NEMO-3 Detector• tracker (6k drift cells)• calorimeter (2k PM’s)• magnetic field (25 Gauss)• 10 kg of source (7 isotopes)• passive shielding (4.8k MWE)• 0.3 eV sensitivity (2 x 1024 yr)

IOP HEPP 2009 4Matthew Kauer

Backgrounds1 electron, Zr96 foil

electron + gamma, Zr96 foil

• Verify external bkg with Cu• My analysis on Zr96• 9.4 g isotope

electron + gamma, Cu foil

IOP HEPP 2009 5Matthew Kauer

2vbb Measurement

2vbb signal (blue) is scaled until the log-likelihood is maximized

Previous Measurement from NEMO-2T2v = [ 2.1 +0.8

-0.4(stat) +/- 0.2(syst)] x 1019 yr

911 daysruntime

IOP HEPP 2009 6Matthew Kauer

0vbb Discussion

Limits on various 0v modes (half-lives in years):

IOP HEPP 2009 7Matthew Kauer

IsotopeIsotope Mass M

Efficiency Internal Bkgs

Energy ResolutionSensitivity

82Se (and/or 150Nd if enrichment possible) 100 - 200 kg~ 30 % 10 Bq/kg4% FWHM @ 3 MeV ( 7% @ 1 MeV )) > 1026 ym < 0.04 - 0.11 eV

SuperNEMO

R&D on:• Isotope enrichment• Drift cell tracker• Software• Calorimeter

UCL London

CENBG Bordeaux, LAL Orsay

INR Kiev, ISMA Kharkov

JINR Dubna

Univ. Texas Austin

1 of 20 sub-modules each with ~5-7 kg of isotope

IOP HEPP 2009 8Matthew Kauer

Test Bench207Bi CE source

Hamamatsu (35% QE)

PMT

BC404 scintillator wrapped in

Teflon

E/E = 6.5% FWHM @ 1 MeV

• 2mm Al. filters out CE’s• fit the gamma spectra• carry parameters over

976 keVce-K

1048 keVce-L

482 keVce-K

554 keVce-L

IOP HEPP 2009 9Matthew Kauer

Baseline Design

18cm

8” HamamatsuR5912-MOD

Super-Bialkali8 Dynodes

25cm

Eljen EJ200PolyVinylToluene

~10k ph/MeV

Glycerol or 2-propanol optical coupling

7.3 - 7.7%FWHM @ 1 MeV

< 1% deviation

Reflective wrappings:• 75um Teflon

≥85% diffusive• 100um ESR

~95% specular

IOP HEPP 2009 10Matthew Kauer

Results

Scint Dimensions FWHM @ 1 MeV

PMT Size and Make

52 x 2 cm BC404 6.5 % 3in Ham-SBA

92 x 2 cm BC408 10.1 % 8in Ham-SBA w/ LG

142 x 2 cm BC404 9.2 % 8in ETL w/ LG

152 x 2 cm BC408 10.3 % 8in Ham-SBA w/ LG

20(hex) x 2 cm BC408 11.2 % 8in Ham-SBA w/ LG

20(hex) x 2 cm EJ200 6.9 % 8in Photonis XP1886

20(hex) x 10 cm EJ200 7.5 % 8in Ham-SBA R5912-MOD

20(hex) x 10 cm EJ200 7.1 % 8in Photonis XP1886

Independent verification with calibrated Sr90 test-bench at CENBG, Bordeaux.

error ± 0.5%

IOP HEPP 2009 11Matthew Kauer

Conclusions

ΔE/E = 7.1% FWHM at 1 MeV

• 32% QE PM• 10k ph/MeV PVT

World best Zr96 Measurement:

Unprecedented ΔE/E for low Z scint:

Full write-up about to be submitted to NucPhys A

To be submitted to NIM A

IOP HEPP 2009 12Matthew Kauer

BONUS

IOP HEPP 2009 13Matthew Kauer

Event ReconstructionSophisticated event reconstruction:

• single electron• electron + gamma(s)• electron + delayed alpha• gamma(s) + alpha• etc…

• Separation of source and detector• Calorimeter• Drift cell tracker in Geiger mode• Time-of-flight information• Magnetic field for charge identification

IOP HEPP 2009 14Matthew Kauer

External BackgroundsarXiv:0903.2277v1 [nucl-ex], submitted to NIM A

IOP HEPP 2009 15Matthew Kauer

Internal Backgrounds1 electron, 911 days runtime

IOP HEPP 2009 16Matthew Kauer

Internal Backgrounds1 electron + 1 gamma, 911 days runtime

IOP HEPP 2009 17Matthew Kauer

2vbb Measurement

maximized log- likelihood fit

IOP HEPP 2009 18Matthew Kauer

0vbb DiscussionLimits obtained via the log-likelihood ratio test statistic:

IOP HEPP 2009 19Matthew Kauer

Majorons

IOP HEPP 2009 20Matthew Kauer

SuperNEMOSuperNEMO ~ 90 physicists, 12 countries• currently on 3 year R&D phase (ends late ’09)

IsotopeIsotope Mass M

Efficiency Internal Bkgs

Energy ResolutionSensitivity

82Se (and/or 150Nd if enrichment possible) 100 - 200 kg~ 30 % 10 Bq/kg4% FWHM @ 3 MeV ( 7% @ 1 MeV )) > 1026 ym < 0.04 - 0.11 eV

R&D on:• Isotope enrichment• Drift cell tracker• Software• Calorimeter

UCL London

CENBG Bordeaux, LAL Orsay

INR Kiev, ISMA Kharkov

JINR Dubna

Univ. Texas Austin

IOP HEPP 2009 21Matthew Kauer

M mass (g) efficiencykC.L. confidence levelN Avogadro numbert time (y)NBkg background events (keV-1.g-1.y-1)

E energy resolution (keV)

>A

M . tNBkg . ET

0

2/1 (y) . .ln2 NkC.L.

.

12% FWHM @ 1 MeV

8% FWHM @ 1 MeV

Even with ideal M, Nbkg, 2 and 0 mix at low E

Energy Resolution

IOP HEPP 2009 22Matthew Kauer

The DetectorSingle sub-module with ~5-7 kg of isotope

~20 sub-modules for 100+ kg of isotope surrounded by water shielding

~ 40-60k Geiger channels for tracking~ 10-20k PMTs source foils

water