double beta decay, neutrino physics and something else 1 1.the birth of double beta decay 2.from low...

Double beta decay, neutrino physics and something else

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1. The birth of double beta decay2. From low energy nuclear physics to neutrino mass and

properties3. The physics of rare events 4. Experimental approaches and difficulties5. Present experimental status6. The future7. The nightmare of nuclear matrix elements 8. Something else9. Conclusions

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Double beta decays

1935 M.Goeppert-Mayer, P.R. 48 (1935) 512 T>1020

Majorana, Nuovo Cimento 14 (1937) 171 Symmetric Theory of Electron and Positron G. Racah, Nuovo Cimento 14 (1937) 322

W.H. Furry Lepton number nonconservation

1967: 130Te, Geochemical Ogata and Takaoka, Kirsten et

1987: 82Se, Direct counting Moe et al .1987 : Source=detector 48Ca, 76Ge

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1. (A,Z) => (A,Z+2) + 2 e- + 2 e

Two neutrino double beta decay Allowed by the standard model Found in eleven nuclei ( 130Xe is new!) to ground state and in two

to excited state

2. (A,Z) => (A,Z+2) + 2 e- + ( …2,3 ) Emission of a massless Goldston boson named Majoron (Gelmini and Roncadelli)

3. (A,Z) => (A,Z+2) + 2 e-

Neutrinoless double beta decay. The two electrons share the total transition energy E1 + E2 => E => a peak should appear in the sum spectrum of the two electrons

Other possible “L=2” decays- Double positron decay => + + - Positron decay + Electron Capture => EC- + - Double electron capture => EC-EC

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Two neutrino and neutrinoless double beta decay

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Measurement of the CP phase in the decay

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e-

e-

Direct experiments

Source detectors Source = detector

Geochemical experiments82Se = > 82Kr, 96Zr = > 96Mo, 128Te = > 128Xe , 130Te = > 130TeRadiochemical experiments 238U = > 238Pu (non confirmed)

How to search for decay

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Many types of detectors

Experimental challenges

• Cloud chambers

• Emulsions?

• Bubble chambers ? (yes for Dark Matter)

• Scintillators

• Double state liquids

• Time projectrion chambers

• Tracking and imagining devices

• Single atom counters 136Xe => 136Ba

• Bolometers

• Hybrid devices

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A first source = detector experiment

RARE events One of the main problem => background

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Cosmic rays => underground physics

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Where to go ?

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The Jin Ping Laboratory (700 m.w.e)

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Radioactivity

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The second mystery of Ettore Majorana

In 1937, Majorana [2] theoretically showed that the conclusions ofthe theory of β decay remain unchanged under the assumption of the existence of only one type of the neutrino having no antiparticle

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e e

→ → <= =>

Majorana =>1937

Dirac or Majorana neutrino?

RIGHT

LEFT:

:

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EXO-200 => 2.71±0.017(stat.)±0.06(sys.)×1021 yr.

Kamland-Zen 2.38 ± 0.02(stat) ± 0.14(syst) × 1021 yr GERDA I 1.84 +0.14 -10(stat) × 1021 yr

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Neutrino oscillations

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Sterile neutrinosLSND,Miniboon,Gallex,reactors

Great discovery requires great evidence (P. de Bernardis)

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<m> ~ 0.34eV

Bracking news then 0 in 76Ge

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GERDA

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Complain by H.Klapdor

Future experiments on DBD

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GERDA Majorana Supernemo

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SNO+

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NEXT

Incident particle

absorber crystal

Thermal sensor

Energy resolution <1 eV ~ 1eV @ 6 keV ~10 eV ~keV @ 2 MeV

VC

Q T

J/K )( v

v 1944 C 3

m V

T

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Thermal detectors

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CUORICINO CUORE0 CUORE

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Hybrid techniquesHeat+ scintillation , light, Cherenkov light

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Crystal made from

ββ-isotopes

Thermometer

Light detector

Heat sink

Heat sink

0νββ emitters: 130Te, 82Se, 100Mo & few others

Crystals: TeO2 , ZnSe, ZnMoO4, CaMoO4

Operation at <20 mK:

Cuore (w/o light detection)

Lucifer, Lumineu, Amore(with light detection)

Lucifer

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Qββ (82Se) = 2995 keVArray of 32-36 enr. (95%) Zn82Se crystals

Total 82Se nuclei: (6.7-8.0) 1025

Single detector: 460 gBI (goal): 1-2 x10-3 cts / (keV kg yr)

ΔE (FWHM): 10-15 keV • Bgd (internal α’s):17.2±4.6 μBq/kg (232Th)24.6±5.5 μBq/kg (238U)• Isotope delivery:

9/15 kg 82Se delivered final batch for

02/2015 • Crystal growth:

Schedule for Jan - June 2015Current yield: 70%

‘anomalous β/γ-quenching’

Now a competitor AMORE

Advanced Mo based Rare process Experiment

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Before the nightmareFrancesco Jachello entering the field

The nightmare of matrix elements

Robertson idea

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Is Francesco Iachello right ?

Amicus Plato, sed magis amica veritasPlato is a friend , but truth even a better one

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Detectors of unprecedentent sensitivity Environmental radioactivity Trace elements Archaeometry

Reactors => friends and enemiesIs neutrinoless double beta decay the only way to test lepton conservation?

A possible experiment to search

e =>

A favor to be returned => reactor physics

=> Measurement of the position of the fire inside the reactor=> Displacement of the Uranium column in the core

Majorana neutrino and consequences

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Radionuclide OriginGamma Peak (keV)

Branching ratios (%)

Absolute detection efficiency εabs (%)

Min (μ Bqm−3)Max (μ Bqm−3)

Mean (μ Bqm−3)

7Be Cosmogenic 477 10.3 0.69 ± 0.10 200 ± 40 970 ± 190 470 ± 90

131I Fukushima284 81.2 1.08 ± 0.16 23 ± 4 410 ± 82 82 ± 16

364 60.6 0.88 ± 0.13

134Cs Fukushima604 97.6 0.57 ± 0.09 1.3 ± 0.3 80 ± 16 9.2 ± 1.8

796 85.4 0.47 ± 0.07

136Cs Fukushima 818 100 0.46 ± 0.07 0.005 ± 0.001

137Cs Fukushima 661 84.6 0.54 ± 0.08 1.6 ± 0.3 93 ± 19 10 ± 2

The Fukushima accident. Agreement by groups =>Measurements of air contamination in Osaka, Berkeley, Seattle etc. Only partially related to the distance Detection of air contamination a factor of million less in Milan with respect to Fukushima

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Majorana theory for electron and positron

Application to neutrino => can a ½ spin particle be its own antiparticle? In superconductors Cooper pairs, being boson like particles, form condensates. Cooper pairs can be added to semiconductors with hole producing spin ½ exitons.Superconductors can contain magnetic wires acting as quasiparticlesCan the Majorana rule be applied to these quasiparticles?

Massive detectors (now expensive) of unique sophistication

The reduction of the background which could hide neutrinolessevents has reached an unprecedented sensistivity

The quenching due to the new value assummed for gA could reduce the expecttion of the neutrino mass limit by a factor 4 to 5. If true it strongly reduces our hope to reach the invers hierarchy region

The validity to extend to neutrinoles DBD the gA obtained from

two neutrino and single beta decay should be justified

The sophistication reached and to be reached in serches for DBD could have appplications in other fields of science

Aplication to solid state physics of the Maiorana theory could bring to results as important as in elementary particle physics

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Conclusions

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There are more things in Earth and Heaven , Polonius, that can be dreamt of by your Philosophy Hamlet

Benasque March 19,2015

Ettore Fiorini