Neutrinos:Neutrino Oscillation

2v & 0v Double Beta Decay

Theo LongAbraham Apellanes

SPCS Particle Physics 2014

NeutrinosLeptonsCharge 0Very small mass3 flavors:

ve ντ

vμ

Neutrino Oscillation1st theorized in 1957Accepted after results from

SNO detectorStill key problems to be

solved such as mass hierarchy problem and theorized 4th and 5th eigenstates

What is it?ve ντ

vμ Mass Eigenstates Flavour Eigenstates

The Solar Neutrino Problem4p → 4He + 2e+ + ve

Energies range from <0.1 MeV to 20 MeV

Bahcall and Davis 1968

Calculated number of 37Ar atoms expected in a tank

filled with chlorine-based cleaning fluid C2Cl4

Actual number about ⅓ of what was expected

Possible SolutionsSolar Standard ModelExperimental errorNew Physics…

Further ExperimentsNew detectors such as SAGE

and GALLEX builtSuperKamiokande detector in

Japan observed slightly reduced lack of neutrinos

SNO experiment set up in Canada

With higher sensitivity to other types of neutrinos (muon, tau), found the solution to Solar Neutrino Problem

● Previous experiments inadequate for measurement of solar neutrinos due to inability to detect other flavours

● New results show the total of all neutrino flavours agree with solar neutrino estimations

Going FurtherTesting of the Standard Solar ModelNeutrino massNeutrino mass heirarchyOther parameters: θ, δcp

(2v) Double Beta Decay

● First proposed by Maria Goeppert Mayer in 1935.

● ββ Decay - Two β-minus decays● Two neutrons decay into two

protons by emission of two electrons and two electron antineutrinos.

(2v) Double Beta Decay

● Observed in few isotopes for which other types of decay do not occur.

● β decay forbidden by energy conservation laws.

● 35 isotopes are capable ofundergoing 2vββ decay.

● 11 isotopes have been observed.

2vββ Decay Half-life(T1/2,2ν)-1 = a2ν F2ν |M2ν|2 / log(2)

● a2ν approx. = 2E10^-22 (dimensional factor)

● F2ν = phase space factor

● M2ν = nuclear matrix element

A Majorana Particle?● Ettore Majorana theoretically demonstrates that the results of all beta

decay would remain the same if the neutrino is its own antiparticle - a majorana particle (1937)

● Wendell Furry proposes the idea that if the neutrino were a majorana particle, 2vββ may occur without the emission of any (anti-)neutrinos (1939)

0v Double Beta Decay

● If neutrinos:○ are majorana particles○ (at least one type) have non-zero mass

● The neutrons will each decay into a protonwith the emission of two electrons.

○ the neutrinos will annihilate○ the neutrinos will be absorbed

by a nucleon

Future Experiments & Implications

● Observing 0vββ would:○ confirm that the neutrino is its own antiparticle○ give information on their absolute mass○ give information on neutrino mass hierarchy

● SuperNEMO - Neodymium-150, Se-82, Ca-48● MAJORANA - Germanium-76● SNO+ (Sudbury Neutrino Observatory) - Te-130

Thank You for your Attentionhttp://www2.lbl.gov/abc/wallchart/chapters/03/2.htmhttp://nemo.in2p3.fr/physics/dbd.phplhttp://nemo.in2p3.fr/supernemo/http://en.wikipedia.org/wiki/Double_beta_decayhttp://en.wikipedia.org/wiki/MAJORANAhttp://en.wikipedia.org/wiki/Neutrino_Ettore_Majorana_Observatory#SuperNEMOhttp://en.wikipedia.org/wiki/SNO%2B