The Search for Neutrinoless Double Beta Decay

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The Search for Neutrinoless Double Beta Decay Tashi Parsons-Moss BNL NCSS 2006

description

The Search for Neutrinoless Double Beta Decay. Tashi Parsons-Moss BNL NCSS 2006. β Decay and Weak Interaction. (A, Z)  (A, Z + 1) + β - +  e (1) (A, Z)  (A, Z - 1) + β + +  e (2) (A, Z) + e -  (A, Z - 1) +  e (3). Neutrinos.  e ,  µ ,   - PowerPoint PPT Presentation

Transcript of The Search for Neutrinoless Double Beta Decay

Page 1: The Search for Neutrinoless Double Beta Decay

The Search for Neutrinoless Double Beta Decay

Tashi Parsons-Moss

BNL NCSS 2006

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β Decay and Weak Interaction

(A, Z) (A, Z + 1) + β- + e (1)

(A, Z) (A, Z - 1) + β+ + e (2)

(A, Z) + e- (A, Z - 1) + e (3)

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Neutrinos

e , µ , 1930 – postulated by

Pauli 1956 – detected by

Cowen et al. Oscillations and Mass

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Double Beta Decay (A, Z) → (A, Z + 2) + 2e- + 2(48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 128Te, 130Te, 150Nd, 238U)

(A, Z) → (A, Z + 2) + 2e-

(A, Z) → (A, Z + 2) + 2e- + 0(+0)

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Possible Mechanisms of 0ββ decay

SUSY particles

Leptoquarks

Right-Handed weak

interaction

Light of Heavy

Majorana Neutrinos

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0ββ Decay and Neutrino Mass

3 Ranges of Mass sensitivity: Quasi-Degenerate

~100-500 meV Atmospheric neutrino

oscillation results ~20-55 meV

Solar neutrino oscillation results ~2-5 meV

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What’s the big deal?

= ?

Absolute mass scale for

neutrinos

Leptogenesis

Weak Force

Grand Unified Theories

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Challenges

Determining the dominant mechanism Uncertainties in nuclear matrix elements Limited resources, expense Background, background, Background!!!

2ββ peak Cosmic radiation Intrinsic background Shielding and cryostat material

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Recent 0ββ results

Isotope Exposure (kmol-y) Background (counts)

Half-Life Limit (y) Effective Neutrino Mass Limit (meV)

48Ca 5 x 10-5 0 > 1.4 x 1022 < 7200-44700

76Ge 0.467 21 > 1.9 x 1025 < 350

76Ge 0.117 3.5 > 1.6 x 1025 < 330 - 1350

76Ge 0.943 61 = 1.2 x 1025 = 440

82Se 7 x 10-5 0 > 2.7 x 1022

(68%)< 5000

100Mo 5 x 10-4 4 > 5.5 x 1022 < 2100

116Cd 1 x 10-3 14 > 1.7 x 1023 < 1700

128Te Geochemical NA > 7.7 x 1024 < 1100-1500

130Te 0.025 5 > 5.5 x 1023 < 370 - 1900

136Xe 7 x 10-3 16 > 4.4 x 1023 < 1800-5200

150Nd 6 x 10-5 0 > 1.2 x 1021 < 3000

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Recent claim of 0ββ detection

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Heidelberg-Moscow

71.7 Kg-y data

Controversial Results

Increased interest in

quasi-degenerate 76Ge

experiments

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0ββ ProposalsCollaboration Isotope (kmol) Anticipated Background

(counts/y)Detector Description

CAMEO 116Cd (2) Few CdWO4 crystals in liquid scintillator

CANDLES 48Ca (0.04) CaF2 crystals in liquid scintillator

COBRA 130Te CdTe semiconductors

CUORE 130Te (1.4) ≈ 60 TeO2 bolometers

DCBA 82Se (2) ≈ 40 Nd foils and tracking chambers

EXO 136Xe (4.2) < 1 Xe TPCGEM 76Ge (11) ≈ 0.8 Ge detectors in LNGENIUS 76Ge (8.8) ≈ 0.6 Ge detectors in LNGSO 160Gd (1.7) Gd2SiO5 crystals in

liquid scintillatorMajorana 76Ge (3.5) ≈ 1 Segmented Ge detectorsMOON 100Mo (2.5) ≈ 8 Mo foils and plastic

scintillatorMPI bare Ge 76Ge (8.8) Ge detectors in LN

Nano-crystals ≈ 100 kmol Suspended nanoparticles

Super-NEMO 82Se (0.6) ≈ 1 Foils with trackingXe 136Xe (6.3) ≈ 118 Xe dissolved in liquid

scintillator XMASS 136Xe (6.1) Liquid Xe

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GENIUS (Germanium Nitrogen Underground Setup)

Assumes limiting

background on HM from

external sources

Array of 2.5 Kg p-type

86% enriched Ge

crystals “naked” in LN2

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Majorana

Assumes 68Ge within Ge detectors was limiting background in IGEX

210 86% enriched, segmented n-type Ge crystals in ultra-pure electroformed Cu cryostats

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Majorana

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MOON (Mo Observatory of Neutrinos)

Uses unique nuclear

structure of 100Mo to

combine 0ββ search

and solar neutrino

experiment

Modules of plastic fiber

scintillators with thin

layers Mo

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MOON

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Acknowledgements

I would like to thank Richard Ferrieri and

all of the TA’s, professors, students and

supporters of the BNL Nuclear and

Radiochemistry Summer School