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

Neutrino (mass)2 spectrum } or Normal Inverted From neutrinos... DK&ER lecture11

Various and complementary ways to measure neutrino mass Cosmology Oscillation Beta decay wzory z PDG2008 From neutrinos... DK&ER lecture11

Three roads to neutrino masses

Direct measurements of neutrino masses νe: tritium β decay νμ: π decay ντ: 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 lecture11

β-decay and neutrino mass Model independent neutrino mass from ß-decay kinematics experimental observable is mν2 ß-source requirements : high ß-decay rate (short t1/2) low ß-endpoint energy E0 superallowed ß-transition few inelastic scatters of ß‘s ß-detection requirements : - high resolution (ΔE< few eV) - large solid angle - low background E0 = 18.6 keV T1/2 = 12.3 y

History of tritium measurements From neutrinos... DK&ER lecture11

Electrostatic filter with magnetic adiabatic collimation From neutrinos... DK&ER lecture11

Status of previous tritium measurements Mainz & Troitsk have reached their intrinsic limit of sensitivity Troitsk Mainz windowless gaseous T2 source quench condensed solid T2 source analysis 1994 to 1999, 2001 analysis 1998/99, 2001/02 both experiments now used for systematic investigations From neutrinos... DK&ER lecture11

Designing a next-generation experiment experimental observable in ß-decay is mν2 aim : improve mν by one order of magnitude (2 eV  0.2 eV ) requires : improve mν by two orders of magnitude (4 eV2  0.04 eV2 ) problem : count rate close to ß-end point drops very fast (~δE3) improve statistics : stronger tritium source (factor 80) (& large analysing plane, Ø=10m) - longer measuring period (~100 days  ~1000 days) improve energy resolution : large electrostatic spectrometer with ΔE=0.93 eV (factor 4 improvement) reduce systematic errors : - better control of systematics, energy losses (reduce to less than 1/10) 2 L=23 m From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 Katrin From neutrinos... DK&ER lecture11 KATRIN will reach a final sensitivity of 200 meV at 90\% C.L. on the absolute neutrino mass scale.

From neutrinos... DK&ER lecture11 KATRIN experiment Karlsruhe Tritium Neutrino Experiment at Forschungszentrum Karlsruhe unique facility for closed T2 cycle: Tritium Laboratory Karlsruhe TLK ~ 75 m linear setup with 40 s.c. solenoids From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 Transport of KATRIN Complicated transport of the spectrometer in Dec. 2006 From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 KATRIN sensitivity sensitivity optimisation: LoI (2001)  reference design (2004) improved statistics: source luminosity, scanning reduced systematics: ß-energy losses in source improved sensitivity sensitivity (90% CL) m(ν) < 0.2 eV discovery potential m(ν) = 0.35 eV (5σ) From neutrinos... DK&ER lecture11

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 lecture11

Dirac neutrino vs Majorana neutrino Majorana particles Special case: particle is it’s own anti-particle Dirac particles Lorentz Boost, E, B C P T C P T only neutral particles are candidates for beeing Majorana particle Example of such is π0 Spinor is fermion representation (in Dirac equation) For particles with m=0 reduces to 2 non-zero states

From neutrinos... DK&ER lecture11 Double beta decays From neutrinos... DK&ER lecture11

Double Beta Decay Candidates From neutrinos... DK&ER lecture11

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

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

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

Candidate Nuclei for Double Beta Decay Q (MeV) Abundance(%) 48Ca→48Ti 4.271 0.187 76Ge→76Se 2.040 7.8 82Se→82Kr 2.995 9.2 96Zr→96Mo 3.350 2.8 100Mo→100Ru 3.034 9.6 110Pd→110Cd 2.013 11.8 116Cd→116Sn 2.802 7.5 124Sn→124Te 2.228 5.64 130Te→130Xe 2.533 34.5 136Xe→136Ba 2.479 8.9 150Nd→150Sm 3.367 5.6 From neutrinos... DK&ER lecture11

Electron spectrum from double β decays Missing energy Energy resolution High rates capabilities From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 ββ history 1935 - ββ(2ν) rate first calculated by Maria Goeppert-Mayer 1937 - Majorana proposes his theory of two-component neutrino 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 82Se Why it took so long? Background t1/2(U, Th) ~ 1010 years while signal: t1/2(2νββ) ~ 1020 years But next we want to look for a process with: t1/2(0νββ) ~ 1025-27 years From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 ββ history 2004 – controversial claim of observation of 0νββ: From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11

Experiments with active targets From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 76Ge spectrum From neutrinos... DK&ER lecture11

From neutrinos... DK&ER lecture11 76Ge spectrum with a possible 0νββ peak From neutrinos... DK&ER lecture11

76Ge spectrum with a possible 0νββ peak Exposure (total): 71.7 kg.y Clearly this needs to be verified...

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 … Uzywaja detektorow germanowych Klapdora

Tracking and calorimeter Experimental techniques Calorimeter Source=detector Resolution, efficiency Background, isotope choice Tracking and calorimeter Source ≠ detector TPC (Xe) Efficiency, Mass Main features: High energy resolution Modest background rejection Main features: High background rejection Modest energy resolution 0νββ 0νββ F. Piquemal (CENBG) LP07

Separation of 0νββ from 2νββ 0nbb spectrum (5% FWHM) (normalized to 10-6) 2νββ spectrum (normalized to 1) E1 + E2 (normalized to Qββ) Energy resolution is essential 0νββ spectrum (5% FWHM) (normalized to 10-2) F. T. Avignone, G. S. King and Yu. G. Zdesenko, ``Next generation double-beta decay experiments: Metrics for their evaluation,’’ New J. Phys. 7, 6 (2005). from S. Elliott and P. Vogel

Fréjus Underground Laboratory : NEMO-3 detector Fréjus Underground Laboratory : 4800 m.w.e. 3 m 4 m B (25 G) 20 sectors Source: 10 kg of ββ isotopic foils area = 20 m2, thickness ~ 60 mg/cm2 Tracking detector: drift wire chamber operating (9 layers) in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs Magnetic field: 25 Gauss Gamma shield: pure iron (d = 18cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since March 2004: water + boron) Particle ID: e-, e+, γ and α

Fréjus Underground Laboratory : 4800 m.w.e. NEMO-3 detector Fréjus Underground Laboratory : 4800 m.w.e. Source: 10 kg of isotopic foils area = 20 m2, thickness ~ 60 mg/cm2 Tracking detector: drift wire chamber operating (9 layers) in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs Magnetic field: 25 Gauss Gamma shield: pure iron (d = 18cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since March 2004: water + boron)

ββ decay isotopes NEMO-3 ββ2ν measurement 116Cd 405 g Qbb = 2805 keV 96Zr 9.4 g Qbb = 3350 keV 150Nd 37.0 g Qbb = 3367 keV 48Ca 7.0 g Qbb = 4272 keV 130Te 454 g Qbb = 2529 keV External bkg measurement 100Mo 6.914 kg Qbb = 3034 keV 82Se 0.932 kg Qbb = 2995 keV natTe 491 g Cu 621 g ββ0ν search (All enriched isotopes produced in Russia)

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

ββ events in NEMO-3 experiment Typical ββ2ν event observed from 100Mo Top view Side view From neutrinos... DK&ER lecture11

During installation AUGUST 2001

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 1981-1982

From neutrinos... DK&ER lecture11 100Mo ββ2ν results (Data Feb. 2003 – Dec. 2004) Sum Energy Spectrum Angular Distribution 219 000 events 6914 g 389 days S/B = 40 219 000 events 6914 g 389 days S/B = 40 NEMO-3 NEMO-3 100Mo 100Mo Data Data ββ2ν Monte Carlo ββ2ν Monte Carlo Background subtracted Background subtracted E1 + E2 (keV) Cos(ϑ) 7.37 kg.y T1/2 = 7.11 ± 0.02 (stat) ± 0.54 (syst) x 1018 y From neutrinos... DK&ER lecture11

Other results from NEMO-3: 2νββ 454 g, 534 days 109 events S/B = 0.25 130Te NEMO-3 NEMO-3 932 g, 389 days 2750 events S/B = 4 82Se E1 + E2 (MeV) 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 133 events S/B 6.76 48Ca 96Zr 150Nd 948 days 7g 925 days S/B 1.01 9.41g E1 + E2 (MeV) 9.11 +0.25-0.22(stat) ± 0.63 (sys) 1018 y 2.3 ± 0.2 (stat) ± 0.3 (sys) 1019 y 4.4 +0.5-0.4 (stat)± 0.4 (sys) 1019 y

Results for 2β0ν searches Upper limits Isotope Experiment 48Ca HEP Beijing >1.1x1022* 23-50 76Ge Heidelberg-Moscow >5.7x1025 2-8 IGEX >0.8x1025 82Se Irvine >2.7x1022 4-14 NEMO 2 >9.5x1021 96Zr >1.3x1021 100Mo LBL >2.2x1022* 3-111 UCI >2.6x1021 Osaka 5.5x1022 2 NEMO2 >5x1021 130Te Milano >1.4x1023 2-5 136Xe Caltech/PSI/Neuchatel >4.4x1023 150Nd >1.2x1021 5-6 Germanium diode cal. Te02 cryo calorim. Xe TPC From neutrinos... DK&ER lecture11

From Elliot and Vogel, hep-ph/0202264 Neutrinoless ββ-decay limits From Elliot and Vogel, hep-ph/0202264 From neutrinos... DK&ER lecture11

Neutrino mass and mass ordering Quasi Degenerate Inverted Normal Mass ordering – kolejnosc mass, uporzadkowanie ? ? m(“νe”) < 2.2 eV Σmν < 0.14 - 1.3 eV m(“νμ”) < 190 keV m(“ντ”) < 18.2 MeV Mainz-Troitsk 3H decay Cosmological models

What is the scale of neutrino masses? Strumia and F. Vissani, ``Neutrino masses and mixings.’’ arXiv:hep-ph/0606054. F. Feruglio, C. Hagedorn, Y. Lin and L. Merlo, ``Theory of the Neutrino Mass,’’ arXiv:0808.0812 [hep-ph]. Na ciemnoczerwono (ciemnozielono) zaznaczony obszar niepewnosci zwiazany z nieznanymi fazami Majorany. Jasnoczerwono (jasnozielono) niepewnosc parametrow oscylacji mββ may be very tiny in case of cancellations due to phases

Projections – ββ0ν HM Claim NEMO 3 CUORICINO, EXO-200 GERDA(PII) SuperNEMO CUORE,EXO >2020, 1t experiments ( ≥ 2) Cosmologically disfavoured region (WMAP) >>2020, >10t experiment 47

From neutrinos... DK&ER lecture11 Summary Direct neutrino mass measurements – sensitivity good enough only for νe - may be successful in case of inverted hierarchy Search for 0νββ – extremely important because: It may answer the following basic questions: Is the total lepton number conserved? Essential for understanding the matter-antimatter asymmetry in Universe What is nature of neutrinos: Dirac or Majorana ( 0νββ possible only for Majorana neutrinos) - essential for understanding the source of particle masses From neutrinos... DK&ER lecture11