No s is Good News

S. Biller, Oxford University

(The Quest for Neutrinoless Double Decay)

If lepton number is nota conserved quantity,mixing between & can occur (like kaons)

If lepton number is nota conserved quantity,mixing between & can occur (like kaons)

Mixed “Majorana”states have coupledmasses: “See-Saw”

Mixed “Majorana”states have coupledmasses: “See-Saw”

L

R

L

R

For each flavour,“fundamental”symmetric statehas 4 distinct s:

For each flavour,“fundamental”symmetric statehas 4 distinct s:

R R

L L

If lepton number is nota conserved quantity,mixing between & can occur (like kaons)

If lepton number is nota conserved quantity,mixing between & can occur (like kaons)

Mixed “Majorana”states have coupledmasses: “See-Saw”

Mixed “Majorana”states have coupledmasses: “See-Saw”

CP violation

Predominantlydecay to matter

Cross-over to baryons(“Sphalerons”)

~ GUT scale

~ sub-ev scale

L

R

L

R

For each flavour,“fundamental”symmetric statehas 4 distinct s:

For each flavour,“fundamental”symmetric statehas 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 eV0.1 eV

= 103

E(115In) ~ 100 TeV

Br = 10-

4

Br = 10-

4

~ 10-47

cm2/eV ~ 10-47

cm2/eV

e-e

Lowest known Q value for beta decay: 115In 115Sn(3/2+)

Q = 155 eV !!Q = 155 eV !!

Easier ways to earn a living !!!

The ONLY Potentially Viable Approach Known isNeutrinoless Double Decay

udd

udu

e-W

e

Single Beta Decay

udd

ddu

udu

udu

e-

e-

W

W

e

e

Maria Goeppert-Mayer 1935

Double Beta Decay

Elliott, Hahn & Moe 1988 (82Se)

udd

ddu

udu

udu

e-

e-

W

W

e

e

Double Beta Decay

Ettore Majorana 1937 Maria Goeppert-Mayer

1935

Elliott, Hahn & Moe 1988 (82Se)

However, if e could somehowchange into e

…

Wendell Furry 1939

udd

ddu

udu

udu

e-

e-

W

W

e

e

Double Beta Decay

Elliott, Hahn & Moe 1988 (82Se)

Maria Goeppert-Mayer 1935

Ettore Majorana 1937

However, if e could somehowchange into e

…

Wendell Furry 1939

udd

ddu

udu

udu

e-

e-

W

W

e

e

e

e-

e-

Neutrinoless Double Beta Decay

Elliott, Hahn & Moe 1988 (82Se)

Maria Goeppert-Mayer 1935

Ettore Majorana 1937

However, if e could somehowchange into e

…

Wendell Furry 1939

= G0(E0,Z) |M0GT – (gV/gA)2 M0

F|2

<m>2

Exactly calculable phase integral

Nuclear matrix elements(not so exactly calculable)

= miU2ei

Effectiveneutrino mass

Signal Dominated Regime Background Dominated Regime

<m> bound

∞ bound

∞bound

detection

<m> bound

∞1/4 1

MT <m> bound

∞1/4 E

MT

So,

Ouch!

½

∞ (S)½ ≈ (MT)½

target counting mass time

∞ S√B

MT √MTE ≈

energy range examined

H.V. KLAPDOR-KLEINGROTHAUS et al., 2001

76Ge

NEMO 3

Internal Backgrounds:

External Backgrounds:

SuperNEMO UK Involvment: UCL, Manchester, ImperialSuperNEMO UK Involvment: UCL, Manchester, Imperial

Laboratoire Souterrain de Modane

UK cost ~10-15M

Replace 1000 tonnes of ultrapure D2O 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 8B solar neutrinos (& possibly 7Be)

o Geo-neutrinoso 240 km baseline reactor neutrino oscillationso 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 8B solar neutrinos (& possibly 7Be)

o Geo-neutrinoso 240 km baseline reactor neutrino oscillationso Supernova neutrinos

Physics with Liquid ScintillatorPhysics with Liquid Scintillator

Now part of largerSNOLAB majorunderground science facility.

Nigel Smith is the new director.

SNO+ AV Hold Down

ExistingAV SupportRopes

SNO+ AV Hold Down

AV Hold DownRopes

ExistingAV SupportRopes

• 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:

228Th and 228Ra in 10 tonnes of 10% Nd (in form of NdCl3 salt) down to

< 10-14 g 232Th/g NdA reduction of >106 relative

to raw salt measurement!!!

A reduction of >106 relative

to raw salt measurement!!!

150Nd (5% natural abundance)

Loaded by carboxylate technique developed at Brookhaven

< 10-17 g 228Ra/228Th per g scintillator< 10-17 g 228Ra/228Th per g scintillatordemonstated by Borexino & KamLAND

mixing

Purification Spike Tests

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

3 Years of data, m=350meV, U/Th = 10-17 g/g0.1% natural Nd loading, IBM-2 matrix elements3 Years of data, m=350meV, U/Th = 10-17 g/g0.1% natural Nd loading, IBM-2 matrix elements

1st data 2012

Clear confirmation or restrictive bound below Klapdor region by 2015

How do you firmly establish whethera possible signal is actually 02

Two methods:1) Redundancy2) Redundancy

Different isotopes with signals predictedat different energies, with different backgrounds, and different signal rates that scale correctly with the corresponding matrix elements.

600

500

400

300

200

100

02010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

CUORECUORE

GERDA I

EXO

SUPERNEMO

SNO+ II ?CUORE II ?

SUPERNEMO

COBRA ?

m (

meV

)

By 2015, neutrino masses above ~100 meV will eitherbe 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 largermasses/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:

600

500

400

300

200

100

02010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

CUORECUORE

GERDA I

EXO

SUPERNEMO

SNO+ II ?CUORE II ?

SUPERNEMO

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, 2007also Gehman & Elliott, 2007