Neutrino masses Determination of absolute mass scale with

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Neutrino masses Determination of absolute mass scale with beta decays: v single beta decays:

Neutrino masses Determination of absolute mass scale with beta decays: v single beta decays: energy spectra v search for neutrinoless double beta decays The latter is extremely important in order to understand the Universe and sources of particle masses 1

Neutrino (mass)2 spectrum } or (Mass)2 } Normal Inverted From neutrinos. . . DK&ER

Neutrino (mass)2 spectrum } or (Mass)2 } Normal Inverted From neutrinos. . . DK&ER lecture 11 2

Various and complementary ways to measure neutrino mass Cosmology Oscillation Beta decay From neutrinos.

Various and complementary ways to measure neutrino mass Cosmology Oscillation Beta decay From neutrinos. . . DK&ER lecture 11 3

Three roads to neutrino masses 4

Three roads to neutrino masses 4

Direct measurements of neutrino masses vν e: tritium β decay vν μ : π

Direct measurements of neutrino masses vν e: tritium β decay vν μ : π decay vν τ : τ decay Information from the end of the energy spectrum. „Mass” of flavor α – combination of mass states. Very high precision of measurements needed. Up to now only limits. From neutrinos. . . DK&ER lecture 11 5

β-decay and neutrino mass Model independent neutrino mass from ß-decay kinematics experimental observable is

β-decay and neutrino mass Model independent neutrino mass from ß-decay kinematics experimental observable is mν 2 E 0 = 18. 6 ke. V T 1/2 = 12. 3 y ß-source requirements : - high ß-decay rate (short t 1/2) - low ß-endpoint energy E 0 - superallowed ß-transition - few inelastic scatters of ß‘s ß-detection requirements : - high resolution (ΔE< few e. V) - large solid angle 6 - low background

History of tritium measurements From neutrinos. . . DK&ER lecture 11 7

History of tritium measurements From neutrinos. . . DK&ER lecture 11 7

Electrostatic filter with magnetic adiabatic collimation From neutrinos. . . DK&ER lecture 11 8

Electrostatic filter with magnetic adiabatic collimation From neutrinos. . . DK&ER lecture 11 8

Status of previous tritium measurements Mainz & Troitsk have reached their intrinsic limit of

Status of previous tritium measurements Mainz & Troitsk have reached their intrinsic limit of sensitivity Troitsk Mainz windowless gaseous T 2 source quench condensed solid T 2 source analysis 1994 to 1999, 2001 analysis 1998/99, 2001/02 both experiments now used for systematic investigations From neutrinos. . . DK&ER lecture 11 9

Designing a next-generation experimental observable in ß-decay is mν 2 aim : improve mν

Designing a next-generation experimental observable in ß-decay is mν 2 aim : improve mν by one order of magnitude (2 e. V 0. 2 e. V ) requires : improve mν 2 by two orders of magnitude (4 e. V 2 0. 04 e. V 2 ) problem : count rate close to ß-end point drops very fast (~δ E 3) • improve statistics : - stronger tritium source (factor 80) (& large analysing plane, Ø=10 m) - longer measuring period (~100 days ~1000 days) L=23 m • improve energy resolution : - large electrostatic spectrometer with ΔE=0. 93 e. V (factor 4 improvement) - reduce systematic errors : - better control of systematics, energy losses (reduce to less than 1/10) From neutrinos. . . DK&ER lecture 11 10

Katrin From neutrinos. . . DK&ER 11 lecture 11 KATRIN will reach a final

Katrin From neutrinos. . . DK&ER 11 lecture 11 KATRIN will reach a final sensitivity of 200 me. V at 90% C. L. on the absolute neutrino mass scale.

KATRIN experiment Karlsruhe Tritium Neutrino Experiment TLK at Forschungszentrum Karlsruhe unique facility for closed

KATRIN experiment Karlsruhe Tritium Neutrino Experiment TLK at Forschungszentrum Karlsruhe unique facility for closed T 2 cycle: Tritium Laboratory Karlsruhe ~ 75 m linear setup with 40 s. c. solenoids From neutrinos. . . DK&ER lecture 11 12

Transport of KATRIN Complicated transport of the spectrometer in Dec. 2006 From neutrinos. .

Transport of KATRIN Complicated transport of the spectrometer in Dec. 2006 From neutrinos. . . DK&ER lecture 11 13

KATRIN sensitivity optimisation: Lo. I (2001) reference design (2004) • improved statistics: source luminosity,

KATRIN sensitivity optimisation: Lo. I (2001) reference design (2004) • improved statistics: source luminosity, scanning - • reduced systematics: ß-energy losses in source improved sensitivity (90% CL) m(ν) < 0. 2 e. V discovery potential m(ν) = 0. 35 e. V (5σ) From neutrinos. . . DK&ER lecture 11 14

Search for neutrinoless double beta decays • Why so important? • What it would

Search for neutrinoless double beta decays • Why so important? • What it would tell us (if seen)? Reminder: • Leptons are (mostly) left handed • Anti-leptons are (mostly) right handed • Contribution of states with „wrong helicity” is proportional to: for m=0 particle – no such contribution From neutrinos. . . DK&ER lecture 11 15

Dirac neutrino vs Majorana neutrino Dirac particles Majorana particles Special case: particle is it’s

Dirac neutrino vs Majorana neutrino Dirac particles Majorana particles Special case: particle is it’s own anti-particle C Lorentz P Boost, C T E, B P T Spinor is fermion representation (in Dirac equation) For particles with m=0 reduces to 2 non-zero states only neutral particles are candidates for beeing Majorana particle Example of such is π 0

Double beta decays From neutrinos. . . DK&ER lecture 11 17

Double beta decays From neutrinos. . . DK&ER lecture 11 17

Double Beta Decay Candidates From neutrinos. . . DK&ER lecture 11 18

Double Beta Decay Candidates From neutrinos. . . DK&ER lecture 11 18

Phenomenology of 0νββ and 2νββ • pairing interaction between nucleons (even-even nuclei more bound

Phenomenology of 0νββ and 2νββ • pairing interaction between nucleons (even-even nuclei more bound than the odd-odd nuclei) • e. g. 136 Xe and 136 Ce are stable against β decay, but unstable against ββ decay (β -β - for 136 Xe and β +β + for 136 Ce) odd-odd even-even m(A, Z) > m(A, Z+2) 19

Phenomenology of 0νββ and 2νββ Phase space (very well known) Nuclear matrix element (NME)

Phenomenology of 0νββ and 2νββ Phase space (very well known) Nuclear matrix element (NME) (challenging to calculate) 20

Neutrino mixing and oscillations Pontecorvo – Maki – Nakagawa - Sakata (PMNS) matrix weak

Neutrino mixing and oscillations Pontecorvo – Maki – Nakagawa - Sakata (PMNS) matrix weak eigenstates mass eigenstates 3 mixing angles + 1 phase Solar Atmospheric Reactor Atmospheric Majorana Phases only 0νββ ν 21

Candidate Nuclei for Double Beta Decay Q (Me. V) Abundance(%) 48 Ca→ 48 Ti

Candidate Nuclei for Double Beta Decay Q (Me. V) Abundance(%) 48 Ca→ 48 Ti 4. 271 0. 187 76 Ge→ 76 Se 2. 040 2. 995 3. 350 7. 8 9. 2 2. 8 3. 034 2. 013 2. 802 2. 228 2. 533 2. 479 3. 367 9. 6 11. 8 7. 5 5. 64 34. 5 8. 9 5. 6 82 Se→ 82 Kr 96 Zr→ 96 Mo 100 Mo→ 100 Ru 110 Pd→ 110 Cd 116 Cd→ 116 Sn 124 Sn→ 124 Te 130 Te→ 130 Xe 136 Xe→ 136 Ba 150 Nd→ 150 Sm From neutrinos. . . DK&ER lecture 11 22

Electron spectrum from double β decays • Missing energy • Energy resolution • High

Electron spectrum from double β decays • Missing energy • Energy resolution • High rates capabilities From neutrinos. . . DK&ER lecture 11 23

ββ history q 1935 - ββ (2ν ) rate first calculated by Maria Goeppert-Mayer

ββ history q 1935 - ββ (2ν ) rate first calculated by Maria Goeppert-Mayer q 1937 - Majorana proposes his theory of two-component neutrino q 1987 – Direct laboratory evidence for 2νββ: S. Elliot et al. , Phys. Rev. Lett. 59, 2020, 1987 Direct evidence for two-neutrino double-beta decay in 82 Se q Why it took so long? Background while signal: t 1/2(U, Th) ~ 1010 years t 1/2(2νββ) ~ 1020 years q But next we want to look for a process with: t 1/2(0νββ) ~ 1025 -27 years From neutrinos. . . DK&ER lecture 11 24

ββ history q 2004 – controversial claim of observation of 0νββ: From neutrinos. .

ββ history q 2004 – controversial claim of observation of 0νββ: From neutrinos. . . DK&ER lecture 11 25

From neutrinos. . . DK&ER lecture 11 26

From neutrinos. . . DK&ER lecture 11 26

Experiments with active targets From neutrinos. . . DK&ER lecture 11 27

Experiments with active targets From neutrinos. . . DK&ER lecture 11 27

76 Ge From neutrinos. . . DK&ER lecture 11 spectrum 28

76 Ge From neutrinos. . . DK&ER lecture 11 spectrum 28

76 Ge spectrum with a possible 0νββ peak From neutrinos. . . DK&ER lecture

76 Ge spectrum with a possible 0νββ peak From neutrinos. . . DK&ER lecture 11 29

76 Ge spectrum with a possible 0νββ peak 76 Ge Exposure (total): 71. 7

76 Ge spectrum with a possible 0νββ peak 76 Ge Exposure (total): 71. 7 kg. y Clearly this needs to be verified. . . 30

New experiment with Ge: GERDA To check the questionable result – new experiment with

New experiment with Ge: GERDA To check the questionable result – new experiment with Ge is prepared GERDA (with contribution from Jagiellonian Uniw. ), the background reduction will be better … 31

Experimental techniques Calorimeter Source=detector Resolution, efficiency Main features: Tracking and calorimeter Source ≠ detector

Experimental techniques Calorimeter Source=detector Resolution, efficiency Main features: Tracking and calorimeter Source ≠ detector TPC (Xe) Efficiency, Mass Main features: High energy resolution Modest background rejection 0νββ Background, isotope choice High background rejection Modest energy resolution 0νββ 32

Separation of 0νββ from 2νββ 0 nbb spectrum (5% FWHM) (normalized to 10 -6)

Separation of 0νββ from 2νββ 0 nbb spectrum (5% FWHM) (normalized to 10 -6) 2νββ spectrum (normalized to 1) E 1 + E 2 (normalized to Qββ ) 0νββ spectrum (5% FWHM) (normalized to 10 -2) from S. Elliott and P. Vogel Energy resolution is essential F. T. Avignone, G. S. King and Yu. G. Zdesenko, ``Next generation double-beta decay experiments: Metrics for their evaluation, ’’ New J. Phys. 7, 336 (2005).

NEMO-3 detector Fréjus Underground Laboratory : 4800 m. w. e. Source: 10 kg of

NEMO-3 detector Fréjus Underground Laboratory : 4800 m. w. e. Source: 10 kg of ββ isotopic foils 20 sectors area = 20 m 2, thickness ~ 60 mg/cm 2 Tracking detector: drift wire chamber operating (9 layer in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0. 1% H 2 O Calorimeter: 3 m 1940 plastic scintillators coupled to low radioactivity PMTs B (25 G) 4 m Particle ID: e-, e+, γ and α Magnetic field: 25 Gauss Gamma shield: pure iron (d = 18 cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since March 2004: water + boron) 34

NEMO-3 detector Fréjus Underground Laboratory : 4800 m. w. e. Source: 10 kg of

NEMO-3 detector Fréjus Underground Laboratory : 4800 m. w. e. Source: 10 kg of isotopic foils area = 20 m 2, thickness ~ 60 mg/cm 2 Tracking detector: drift wire chamber operating (9 layer in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0. 1% H 2 O Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs Magnetic field: Gamma shield: 25 Gauss pure iron (d = 18 cm) Neutron shield: water (ex 40 cm wood (to 30 cm bottom) (since March 200 35 water + boron)

ββ decay isotopes NEMO-3 ββ 2ν measurement 116 Cd 405 g Qbb = 2805

ββ decay isotopes NEMO-3 ββ 2ν measurement 116 Cd 405 g Qbb = 2805 ke. V 96 Zr 9. 4 g Qbb = 3350 ke. V 150 Nd 37. 0 g Qbb = 3367 ke. V 48 Ca 7. 0 g Qbb = 4272 ke. V 130 Te 454 g Qbb = 2529 ke. V 100 Mo 6. 914 kg 82 Se Qbb = 3034 ke. V ββ 0ν search 0. 932 kg Qbb = 2995 ke. V nat. Te 491 g Cu 621 g External bkg measurement (All enriched isotopes produced in Russia) 36

PMTs Cathod rings Wire chamber Calibration tube scintillators bb isotope foils 37

PMTs Cathod rings Wire chamber Calibration tube scintillators bb isotope foils 37

ββ events in NEMO-3 experiment Typical ββ 2ν event observed from 100 Mo Side

ββ events in NEMO-3 experiment Typical ββ 2ν event observed from 100 Mo Side view Top view From neutrinos. . . DK&ER lecture 11 38

During installation AUGUST 2001 39

During installation AUGUST 2001 39

Laboratoire Souterrain de Modane 4700 m. w. e COMMISSARIAT À L’ÉNERGIE ATOMIQUE DIRECTION DES

Laboratoire Souterrain de Modane 4700 m. w. e COMMISSARIAT À L’ÉNERGIE ATOMIQUE DIRECTION DES SCIENCES DE LA MATIÈRE Built for taup experiment (proton decay) in 19811982 40

100 Mo ββ 2ν results (Data Feb. 2003 – Dec. 2004) Angular Distribution Sum

100 Mo ββ 2ν results (Data Feb. 2003 – Dec. 2004) Angular Distribution Sum Energy Spectrum NEMO-3 100 Mo 219 000 events 6914 g 389 days S/B = 40 100 Mo • • 219 000 events 6914 g 389 days S/B = 40 NEMO-3 Data ββ 2ν Monte Carlo Background subtracted E 1 + E 2 (ke. V) 7. 37 kg. y Cos(ϑ) T 1/2 = 7. 11 ± 0. 02 (stat) ± 0. 54 (syst) x 1018 y From neutrinos. . . DK&ER lecture 11 41

Other results from NEMO-3: 2νββ NEMO-3 82 Se 932 g, 389 days 2750 events

Other results from NEMO-3: 2νββ NEMO-3 82 Se 932 g, 389 days 2750 events S/B = 4 NEMO-3 454 g, 534 days 109 events S/B = 0. 25 130 Te E 1 + E 2 (Me. V) 9. 6 ± 0. 3 (stat) ± 1. 0 (sys) 1019 y 2. 8 ± 0. 1 (stat) ± 0. 3 (sys) 1019 y 7. 6 ± 1. 5 (stat) ± 0. 8 (sys) 1020 y 48 Ca 96 Zr 150 Nd 925 days S/B 1. 01 9. 41 g 133 events S/B 6. 76 948 days 7 g E 1 + E 2 (Me. V) 9. 11 +0. 25 -0. 22(stat) ± 0. 63 (sys) 1018 y 2. 3 ± 0. 2 (stat) ± 0. 3 (sys) 1019 y 42 1019 y 4. 4 +0. 5 -0. 4 (stat)± 0. 4 (sys)

Xe TPC Te 02 cryo calorim. Germanium diode cal. Results for 2β 0ν searches

Xe TPC Te 02 cryo calorim. Germanium diode cal. Results for 2β 0ν searches Isotope Experiment 48 Ca HEP Beijing Heidelberg-Moscow IGEX Irvine NEMO 2 LBL UCI Osaka NEMO 2 Milano Caltech/PSI/Neuchatel From neutrinos. . . DK&ER UCI lecture 11 76 Ge 82 Se 96 Zr 100 Mo 130 Te 136 Xe 150 Nd Upper limits >1. 1 x 1022* >5. 7 x 1025 >0. 8 x 1025 >2. 7 x 1022 >9. 5 x 1021 >1. 3 x 1021 >2. 2 x 1022* >2. 6 x 1021 5. 5 x 1022 >5 x 1021 >1. 4 x 1023 >4. 4 x 1023 >1. 2 x 1021 23 -50 2 -8 4 -14 3 -111 2 2 -5 5 -6 43

Neutrinoless ββ-decay limits From Elliot and Vogel, hep-ph/0202264 From neutrinos. . . DK&ER lecture

Neutrinoless ββ-decay limits From Elliot and Vogel, hep-ph/0202264 From neutrinos. . . DK&ER lecture 11 44

Neutrino mass and mass ordering Normal ? m(“ν e”) < 2. 2 e. V

Neutrino mass and mass ordering Normal ? m(“ν e”) < 2. 2 e. V Mainz-Troitsk 3 H decay Inverted Quasi Degenerate ? Σmν < 0. 14 - 1. 3 e. V Cosmological models m(“ν μ ”) < 190 ke. V m(“ν τ ”) < 18. 2 45 Me. V

What is the scale of neutrino masses? A. Strumia and F. Vissani, ``Neutrino masses

What is the scale of neutrino masses? A. Strumia and F. Vissani, ``Neutrino masses and mixings. ’’ ar. Xiv: hep-ph/0606054. F. Feruglio, C. Hagedorn, Y. Lin and L. Merlo, ``Theory of the Neutrino Mass, ’’ ar. Xiv: 0808. 0812 [hep-ph]. mββ may be very tiny in case of cancellations due to phases 46

HM Claim NEMO 3 CUORICINO, EXO-200 GERDA(PII) Super. NEMO CUORE, EXO >2020, 1 t

HM Claim NEMO 3 CUORICINO, EXO-200 GERDA(PII) Super. NEMO CUORE, EXO >2020, 1 t experiments ( ≥ 2) >>2020, >10 t experiment Cosmologically disfavoured region (WMAP) Projections – ββ 0ν 47

Summary v Direct neutrino mass measurements – sensitivity good enough only for νe -

Summary v Direct neutrino mass measurements – sensitivity good enough only for νe - may be successful in case of inverted hierarchy v Search for 0νββ – extremely important because: It may answer the following basic questions: Ø Is the total lepton number conserved? Essential for understanding the matter-antimatter asymmetry in Universe Ø What is nature of neutrinos: Dirac or Majorana ( 0ν ββ possible only for Majorana neutrinos) - essential for understanding the source of particle masses From neutrinos. . . DK&ER lecture 11 48