SNOLAB: home of SNO+ & DEAP3600 Exploring the invisibles using - PowerPoint PPT Presentation

SNOLAB: home of SNO+ & DEAP3600 Exploring the invisibles using large liquid scintillator detectors Simon JM Peeters University of Sussex S.J.M.Peeters@sussex.ac.uk May 28, 2015 Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 1 / 64

The Sudbury Neutrino Observatory Some history Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 3 / 64

SNOLAB The stage for the next generation of discoveries Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 7 / 64

Location Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 8 / 64

Northern mining town Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 9 / 64

Features Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 10 / 64

SNOLAB facility above ground Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 11 / 64

Going underground! Actually, recent more stringent safety regulations make this image a little out of date... Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 12 / 64

Walk to mine shaft no. 9 Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 13 / 64

It gets really cold in the winter Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 14 / 64

6800 feet underground - ready to walk a similar distance Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 15 / 64

Arriving at SNOLAB can feel like ... Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 16 / 64

Reality, after required shower and change into clean outfit Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 17 / 64

SNOLAB facility underground Do visit: www.snolab.ca/facility/vr-tour 10,000 square feet class 2000 cleanroom 2078 m deep or 6010 m.w.e.: µ flux only 0.27 m − 2 day − 1 , 120 Bq m − 3 222 Rn http://snolab2008.snolab.ca/snolab_users_handbook_rev02.pdf Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 18 / 64

Worth visiting! Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 19 / 64

Current questions in neutrino physics Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 20 / 64

Neutrino masses & see-saw mechanism As the neutrino is completely neutral, it could be a Majorana particle. Effectively, it is indistinguishable from its anti-particle. The mass term can be written as: � ¯ − 1 2 m M ¯ � L = − m D N R ν L + ¯ ν L N R N R N R + h . c . or: � 0 L = 1 � � ν L � m D ν L , ¯ 2(¯ N R ) m T m M N R D Assuming N R ≫ ν L , we find the two following eigenvalues: (Nearly) right-handed particles with mass m M . (Nearly) left-handed particles with mass m 2 D / m M . See-saw: the heavier m M , the lighter the left-handed neutrino is. Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 25 / 64

Neutrinoless double-beta decay > 10 21 year (!!) ββ , T 0 νββ Rare: Γ = G | M | 2 m 2 1 / 2 Consequences of observation: Violation of lepton number by 2 Schechter-Valle theorem (1982): if neutrinoless double-beta decay is observed, this must mean that neutrinos are Majorana particles! Explanation of why neutrinos are so much lighter. Combined with CP-violation for heavy neutrino, could imply leptogenesis Absolute mass scale hints via m ββ Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 26 / 64

The SNO+ experiment and its programme Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 27 / 64

The SNO+ experiment Low-energy solar neutrinos Supernova neutrinos Reactor anti-neutrinos Geo-neutrinos Invisible nucleon decay Other exotic searches Neutrinoless double-beta decay Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 28 / 64

The SNO+ collaboration Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 29 / 64

SNO+ ‘target’ material Linear alkylbenzene (LAB) + 2,5-diphenyloxazole (PPO) fluor + Te LAB-based scintillator : 0 νββ isotope choice : Around 10,000 photons/MeV High natural abundance of 130 Te in nat Te (34%) Attenuation lenght of about 20 m Favourable rate of 2 νββ to 0 νββ Safe to handle No optical absorption lines Acrylic compatible Stable in liquid scintillator β − α timing discrimination Loading in scintillator due to developments at BNL (NIM A 660 51 (2011) (M. Yeh et al.)) Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 30 / 64

Scintillator plant Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 31 / 64

The expected signal and background 120 0 νββ (200 meV) Counts/5 y/20 keV bin 50 Cts/5 y/122 keV 100 2 νββ 2 νββ 80 U Chain 60 Th Chain 40 40 ( α, n ) 8 B ν ES 20 External 0 8 B ν ES 30 2.2 2.4 2.6 2.8 Cosmogenic T ββ (MeV) Residuals 20 External γ 10 ( α, n ) Cosmogenic Internal U chain Internal Th chain 0 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 T ββ (MeV) 5 years with 0.3% nat Te 200 p.e./MeV 4.5% resolution at Q ββ Fiducial volume: 3.5 m (20%) Energy window: − σ /2 → 3 σ /2 around Q ββ Assume BiPo tags 100% efficient for separate triggers Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 32 / 64

Sensitivity 90% C.L. limits 1 / 2 sensitivity (y) 1 year 10 26 = 3 . 9 × 10 25 year, T 0 νββ ˆ 1 / 2 T 0 ν m ββ ≈ 105 meV ˆ 5 years = 9 . 4 × 10 25 year, T 0 νββ ˆ 1 / 2 m ββ ≈ 68 meV ˆ 90% CL 3 σ CL using: M = 4 . 03 (IMB) G = 3 . 69 × 10 − 14 y − 1 . 10 25 1 2 3 4 5 6 7 8 9 10 Live time (y) Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 33 / 64

Current status and outlook NOW Filling with water Commissioning runs of the detector Commissioning the scintillator plant 2015, second half : water fill Soak Rn daughters from vessel Calibrations and background measurements Invisible nucleon decay, supernova live 2016, first half : scintillator fill Soak Rn daughters from vessel Calibrations and scintillator measurements Reactor anti-neutrino, geo-neutrinos, solar neutrinos, supernova live 2016, second half : Te-loaded scintillator Neutrinoless double-beta decay search Calibrations Reactor anti-neutrino, geo-neutrinos, solar neutrinos, supernova live Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 34 / 64

SNO+ phase II - planning for success Increase to 8 tonne of nat Te 350 (3% loading), 0 νββ (200 meV) Counts/5 y/20 keV bin 2 νββ along with increased light yield, using: 300 U Chain Th Chain 250 ( α, n ) Upgraded PMT array External 8 B ν ES 200 Secondary fluor R&D Cosmogenic 150 Considering central balloon in vessel 100 = 8 × 10 26 year, T 0 νββ ˆ 50 1 / 2 90% C.L. in 5 years 0 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 T ββ (MeV) Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 35 / 64

SNO+ phases in context Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 36 / 64

Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 37 / 64

Why look for Dark Matter? Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 38 / 64

Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 39 / 64

Loads of unknown stuff out there! Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 40 / 64

Dark Matter candidates Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 41 / 64

WIMP scattering WIMP: weakly massive interactive particle The exact interaction mechanism is unknown, so the search is for: Spin independent cross section: coherent scattering, enhanced A 2 dependent cross section. Spin dependent cross section: no such enhancement. Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 43 / 64

Physics reach for Direct Detection of WIMPs Low range (1-10 GeV) : Requires complicated models. High range (100 GeV-1 TeV) : Favoured by simple extensions of the SM -42 10 cMSSM 1- σ contour cMSSM 2- σ contour -43 NUHM 1- σ contour 10 NUHM 2- σ contour Neutrino backgrounds ) LUX (85.3 days) 2 -44 10 DEAP-3600 SI WIMP-proton cross section (cm -45 10 -46 10 -47 10 -48 10 -49 10 -50 10 2 3 10 10 10 2 WIMP mass (GeV/c ) http://cedar.berkeley.edu/plotter , Roszkowski et al, JHEP 1408 (2014) 067, J. Billard et al., Phys. Rev. D 89 (2014) 023524 Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 44 / 64

Detection principle in single-phase argon Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 45 / 64

Direct Detection of Dark Matter SIGNAL Coherent WIMP-nucleus scattering Lewin and Smith, Astroparticle Physics 6, 87-112 (1996) (MAIN) BACKGROUNDS electromagnetic radioactivity ( 39 Ar , 85 Kr ) – reducible surface α particles – reducible external neutrons – reducible neutrinos – irreducible Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 46 / 64

Scintillation of argon Excitation and ionisation leads to * . the production of Ar 2 Light (128 nm) is produced with the * . (Shifted to dissociation of Ar 2 420 nm by TPB wavelength shifter.) * ; Two molecular states of Ar 2 singlet and triplet, with very different lifetimes: 7 ns vs. 1.5 µ s. Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 47 / 64

PSD: Pulse Shape Discrimination Ar: singlet and triplet excited states have well separated lifetimes Simon JM Peeters (USussex) SNO+ & DEAP May 28, 2015 48 / 64