No  s is Good News S. Biller, Oxford University (The Quest for Neutrinoless Double  Decay)

If lepton number is not a conserved quantity, mixing between & can occur (like kaons) If lepton number is not a conserved quantity, mixing between & can occur (like kaons) Mixed “Majorana” states have coupled masses: “See-Saw” Mixed “Majorana” states have coupled masses: “See-Saw” L R L R For each flavour, “fundamental” symmetric state has 4 distinct s: For each flavour, “fundamental” symmetric state has 4 distinct s:  R  R   L  L 

If lepton number is not a conserved quantity, mixing between & can occur (like kaons) If lepton number is not a conserved quantity, mixing between & can occur (like kaons) Mixed “Majorana” states have coupled masses: “See-Saw” Mixed “Majorana” states have coupled masses: “See-Saw” CP violation Predominantly decay to matter Cross-over to baryons (“Sphalerons”) ~ GUT scale ~ sub-ev scale L R L R For each flavour, “fundamental” symmetric state has 4 distinct s: For each flavour, “fundamental” symmetric state has 4 distinct s:  R  R   L  L 

Reasons To Try Marijuana: Majorana o Seesaw mechanism with GUT-scale Majorana neutrino could explain scale of observed neutrino masses o Coupled with CP violation, would be a key feature of Leptogenesis o Would provide an extremely sensitive probe of the absolute neutrino mass

First Attempt: Produce neutrinos at the lowest possible energy, then physically boost to frame of reversed helicity  ~ 100 eV 0.1 eV = 10 3 E( 115 In) ~ 100 TeV Br =  ~ cm 2 /eV e-e- e Lowest known Q value for beta decay: 115 In  115 Sn(3/2+) Q = 155 eV !! Easier ways to earn a living !!!

The ONLY Potentially Viable Approach Known is Neutrinoless Double  Decay

uddudd uduudu e-e- W e Single Beta Decay

uddudd dduddu uduudu uduudu e-e- e-e- W W e e Maria Goeppert-Mayer 1935 Double Beta Decay Elliott, Hahn & Moe 1988 ( 82 Se)

uddudd dduddu uduudu uduudu e-e- e-e- W W e e Double Beta Decay Ettore Majorana 1937 Maria Goeppert-Mayer 1935 Elliott, Hahn & Moe 1988 ( 82 Se) However, if e could somehow change into e … Wendell Furry 1939

uddudd dduddu uduudu uduudu e-e- e-e- W W e e Double Beta Decay Elliott, Hahn & Moe 1988 ( 82 Se) Maria Goeppert-Mayer 1935 Ettore Majorana 1937 However, if e could somehow change into e … Wendell Furry 1939

uddudd dduddu uduudu uduudu e-e- e-e- W W e e e e-e- e-e- Neutrinoless Double Beta Decay Elliott, Hahn & Moe 1988 ( 82 Se) Maria Goeppert-Mayer 1935 Ettore Majorana 1937 However, if e could somehow change into e … Wendell Furry 1939

  = G 0 (E0,Z) | M 0 GT – (g V /g A ) 2 M 0 F | 2 2 Exactly calculable phase integral Nuclear matrix elements (not so exactly calculable) =  m i U 2 ei Effective neutrino mass

Signal Dominated Regime Background Dominated Regime bound ∞  bound ∞  bound  detection bound ∞ 1/4 1 MT bound ∞ 1/4  E MT So, Ouch! ½ ∞  (S) ½ ≈ (MT) ½ target counting mass time ∞  S√B S√B MT √ MT  E ≈ energy range examined

H.V. KLAPDOR-KLEINGROTHAUS et al., Ge

NEMO 3

Internal Backgrounds: External Backgrounds:

SuperNEMO UK Involvment: UCL, Manchester, Imperial

Laboratoire Souterrain de Modane

UK cost ~10-15M

Replace 1000 tonnes of ultrapure D 2 O with 800 tonnes of ultrapure scintillator (so, technically, should be “SNO-”) SNO+ Leeds, Liverpool, Oxford, QMUL, Sussex o Neutrinoless double beta decay o pep and CNO low energy solar neutrinos  tests details of neutrino-matter interaction  solve “Solar Composition Problem” o Low energy 8 B solar neutrinos (& possibly 7 Be) o Geo-neutrinos o 240 km baseline reactor neutrino oscillations o Supernova neutrinos o Neutrinoless double beta decay o pep and CNO low energy solar neutrinos  tests details of neutrino-matter interaction  solve “Solar Composition Problem” o Low energy 8 B solar neutrinos (& possibly 7 Be) o Geo-neutrinos o 240 km baseline reactor neutrino oscillations o Supernova neutrinos Physics with Liquid Scintillator

Now part of larger SNOLAB major underground science facility. Nigel Smith is the new director.

SNO+ AV Hold Down Existing AV Support Ropes

SNO+ AV Hold Down AV Hold Down Ropes Existing AV Support Ropes

Electronics refurbishment Improved cover-gas system New glovebox Repair of liner Re-sanding of acrylic vessel Overhaul of software design New calibration systems New purification systems Replacement of pipes

Radio-purification goals: 228 Th and 228 Ra in 10 tonnes of 10% Nd (in form of NdCl 3 salt) down to < g 232 Th/g Nd A reduction of >10 6 relative to raw salt measurement!!! A reduction of >10 6 relative to raw salt measurement!!! 150 Nd (5% natural abundance) Loaded by carboxylate technique developed at Brookhaven < g 228 Ra/ 228 Th per g scintillator demonstated by Borexino & KamLAND

mixing

Purification Spike Tests spike scintillator with 228 Th (80 Bq) which decays to 212 Pb counted by β-  coincidence liquid scintillation counting

3 Years of data, m =350meV, U/Th = g/g 0.1% natural Nd loading, IBM-2 matrix elements 3 Years of data, m =350meV, U/Th = g/g 0.1% natural Nd loading, IBM-2 matrix elements 1 st data 2012 Clear confirmation or restrictive bound below Klapdor region by st data 2012 Clear confirmation or restrictive bound below Klapdor region by 2015

How do you firmly establish whether a possible signal is actually 0 2  Two methods: 1) Redundancy 2) Redundancy Different isotopes with signals predicted at different energies, with different backgrounds, and different signal rates that scale correctly with the corresponding matrix elements.

CUORE GERDA I GERDA II EXO KAMLAND SUPER NEMO SNO+ II ? CUORE II ? SUPER NEMO COBRA ? m (meV)

By 2015, neutrino masses above ~100 meV will either be firmly established or firmly ruled out based on multiple experiments (including SNO+) using different isotopes. If established, first constraints on several physics mechanisms will likely be made using ratios of lifetimes in these different isotopes. By 2020, SuperNEMO will be also able to confirm signal with Se and use independent method to further constrain RH-current models. If ruled out, all experiments will have to push to larger masses/enrichment to properly test inverted hierarchy. First experiments here might be running by ~2018. OUTLOOK:

o Fully funded by Canada and will start taking data in 2012 o Extremely timely: “could be ready earlier than other competitors.” (PPAN) o Unique detector and facility are firmly established o Extremely High UK Impact: Capitalising on more than 20 years of intellectual investment with track record of significant high profile contributions leading to groundbreaking result and with 10 permanent academics (1/3 of those on entire project) o Remarkably Diverse range of unique physics capabilities o “There is a strong case for the UK to make the require modest investment to participate in SNO+” (PPAP) o Rated Alpha-4 (PPAN) o Extremely cost-effective: For UK, basically just fEC, travel and postdocs (no major hardware, no operating costs, no Common Fund, etc.) “Capitalising on existing infrastructure” (PPAN) (not to mention many years of PPARC/STFC investment) UK cost ~3M SNO+ Status:

CUORE GERDA I GERDA II EXO KAMLAND SUPER NEMO SNO+ II ? CUORE II ? SUPER NEMO COBRA ? m (meV)

A liquid scintillator detector has poor energy resolution... but HUGE quantities of isotope (high statistics) and low backgrounds help compensate Large, homogeneous liquid detector leads to well- defined background model – fewer types of material near fiducial volume (meters of self-shielding) “Source in”/“Source out” capability to test backgrounds, improve purification, etc. Interesting new technique with a rapid timescale SNO+ Double Beta Decay

RH Currents SUSY Models Extra Dimensions Which Mechanism?

Deppisch & Päs, 2007 also Gehman & Elliott, 2007

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