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