Neutrinoless Double Beta Decay with SNO+ · Neutrinoless Double Beta Decay with SNO+ Acrylic...

Neutrinoless Double Beta Decay with SNO+ Acrylic vessel:12 m diameter 780 tonnes LAB liquid scintillator 5700 tonnes H 2 0 outer shielding 1700 tonnes H 2 0 inner shielding ~9400 PMTs, 50% coverage 3.9 tonnes natural Tellurium (1300 kg 130 Te) Experiment Neutrinoless Double Beta Decay (0νββ) Sensitivity With 780 tonnes of linear alkylbenzene (LAB), the SNO+ detector at SNOLAB in Sudbury, Ontario, Canada is one of the largest scintillator detectors in the world. Loading the scintillator with natural tellurium at a fraction of 0.5% by mass provides a tonne-scale experiment and a sensitive search for 0νββ in 130 Te will be performed. Other searches for invisible modes of nucleon decay as well as studies of reactor and solar neutrinos will be ongoing. Features of SNO+ Ø Multipurpose experiment can search for many different neutrino properties Ø Trade off energy resolution for higher statistics Ø Cost-effective since the detector already exists Ø Initial scintillator purification by distillation Ø In-situ purification to further remove backgrounds Background reduction Ø External shielding, 7400 tonnes of water Ø PMTs stand-off from scintillator Ø Self-shielding of scintillator Ø Timing and position cuts Discovery of 0νββ is of key importance to understand the universe and would yield answers to fundamental questions. Ø Is the neutrino its own antiparticle? Ø What is the absolute mass of the neutrino? With lepton number violation, it is possible for two neutrons to simultaneously decay into two protons plus two electrons and no neutrinos. The small neutrino mass suppresses the rate of this process but also gives a handle on that mass. The rate of 0νββ is given by where T 1/2 is the half-life, G is the phase space factor, M is the nuclear matrix element and m ββ is the effective neutrino mass. The key experimental signature for 0νββ is a peak in visible energy at the Q-value of the nucleus, smeared by detector resolution. For year 1, the dominant non-v background sources inside the fiducial volume of 3.5m (ρ < 2m) are external water and AV bulk. (MeV) β β eff T 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 Counts/5 y/20 keV bin 0 10 20 30 40 50 Updated electronics to accommodate higher data rate 2070 m rock overburden shielding New optical monitoring systems Expected signal of all backgrounds and a hypothetical 0νββ signal corresponding to a mass, m ββ = 200 meV, for 5 years of running. Events are shown in the fiducial volume of 3.5m and for 0.5% natural Te loading. SNO+ has picked 130 Te as its isotope of choice for its high natural abundance and ability to be loaded into scintillator. (200 meV) β β ν 0 β β ν 2 U Chain Th Chain , n) α ( , n) α ( External ES ν B 8 Cosmogenic IH NH "# ⁄ %& ’" ∝ %& %& 2 -- 2 Physics Program Ø Neutrinoless Double Beta Decay Ø Low Energy Solar Neutrinos Ø Reactor and Geo Antineutrinos Ø Supernova Neutrinos Ø Nucleon Decay Goal ⟹ Phase II %& %& ×10 "1 6 1.25 # lines of constant For 5 years, 0.5% loading: T 1/2 ~2 × 10 26 y, 90% CL m ββ = 40 – 90 meV Sensitivity increases with isotope loading, can also increase light yield.

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Transcript of Neutrinoless Double Beta Decay with SNO+ · Neutrinoless Double Beta Decay with SNO+ Acrylic...

Neutrinoless Double Beta Decay with SNO+

Acrylic vessel:12 m diameter

780 tonnes LAB liquid scintillator

5700 tonnes H20 outer shielding

1700 tonnes H20 inner shielding

~9400 PMTs, 50% coverage

3.9 tonnes natural Tellurium(1300 kg 130Te)

ExperimentNeutrinoless Double Beta Decay (0νββ)

SensitivityWith 780 tonnes of linear alkylbenzene (LAB), the SNO+ detector at SNOLAB in Sudbury, Ontario, Canada is one of the largest scintillator detectors in the world. Loading the scintillator with natural tellurium at a fraction of 0.5% by mass provides a tonne-scale experiment and a sensitive search for 0νββ in 130Te will be performed. Other searches for invisible modes of nucleon decay as well as studies of reactor and solar neutrinos will be ongoing.

Features of SNO+Ø Multipurpose experiment can search for many different neutrino propertiesØ Trade off energy resolution for higher statisticsØ Cost-effective since the detector already existsØ Initial scintillator purification by distillationØ In-situ purification to further remove backgrounds

Background reductionØ External shielding, 7400 tonnes of waterØ PMTs stand-off from scintillatorØ Self-shielding of scintillatorØ Timing and position cuts

Discovery of 0νββ is of key importance to understand the universe and would yield answers to fundamental questions. Ø Is the neutrino its own antiparticle?Ø What is the absolute mass of the neutrino?

With lepton number violation, it is possible for two neutrons to simultaneously decay into two protons plus two electrons and no neutrinos.

The small neutrino mass suppresses the rate of this process but also gives a handle on that mass. The rate of 0νββ is given by

where T1/2 is the half-life, G is the phase space factor, Mis the nuclear matrix element and mββ is the effective neutrino mass.

The key experimental signature for 0νββ is a peak in visible energy at the Q-value of the nucleus, smeared by detector resolution.

For year 1, the dominant non-v background sources inside the fiducial volume of 3.5m (ρ < 2m) are external water and AV bulk.

(MeV)ββeffT

2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3

Coun

ts/5

y/20

keV

bin

50 (200 meV)ββν0ββν2

U ChainTh Chain

, n)α(External

ESνB 8

Cosmogenic

Updated electronics to accommodate higher data rate

2070 m rock overburden shielding

New optical monitoring systems

Expected signal of all backgrounds and a hypothetical0νββ signal corresponding to a mass, mββ = 200 meV, for 5 years of running. Events are shown in the fiducial volume of 3.5m and for 0.5% natural Te loading.

SNO+ has picked 130Te as its isotope of choice for its high natural abundance and ability to be loaded into scintillator.