1 / 42

Neutrino Physics

Neutrino Physics. Part 3: Absolute neutrino mass Introduction beta decay double beta decay. Caren Hagner Universität Hamburg. Neutrinos have mass! m lightest v ?. Evidence f o r Neutrino Oscillations:. (3).

Download Presentation

Neutrino Physics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Neutrino Physics Part 3: Absolute neutrino mass Introduction beta decay double beta decay Caren Hagner Universität Hamburg

  2. Neutrinos have mass! mlightest v ? Evidence for Neutrino Oscillations: (3) Neutrino oscillations were observed in 2 regions: • Solar neutrinos and reactor neutrinosve → vμ,τ with Δm2 ≈ 8·10-5 eV2, large mixing • Atmospheric neutrinos and accelerator neutrinosvμ→ vτ,(s) mit Δm2 ≈ 2·10-3 eV2, maximal mixing • LSND? Anti-vμ→ Anti-ve with Δm2 ≈ 1eV2 (Tested by MiniBooNE)

  3. 4 component spinor The left-handed and right-handed components are: 2 components each This leads to a system of two coupled equations: With m=0 one obtains the decoupled Weyl equations: Nature of Neutrino Mass I Neutrino fields v(x) with mass m are described by the Dirac equation: From Goldhaber experiment one knows that vL is realized.With m=0 there is no need to have vR. Therefore there were no vR in the Standard Model.

  4. m Dirac Mass Term The neutrino mass term in L could have exactly the same formas the mass term of the quarks and charged leptons: Dirac mass term Lepton number is conserved! Must add vR (right handed SU(2) singlets) to standard model! Problem: When the mechanism is the same, why are the masses so small? mt = 174.3 ± 5.1 GeV; mb = (4.0-4.5) GeV;mτ= 1776.99 ± 0.29 MeV; m3 < 2eV Footnote: A Lorentz invariant mass term must link a chirally left-handed field with a chirally right handed field

  5. particle anti-particle (charge conjugate field): for a Majorana particle: observed! Neutrinos (solar): not observed! Anti-neutrinos(reactor): Majorana Particles Because neutrinos carry no electric charge(and no color charge), there is the possibility: particle ≡ anti-particle Majorana particle But what about experiments? There are two different states per flavorbut the difference could be due to left-handed and right-handed states!

  6. mL vL (vL)c right handed field left handed field Majorana Mass Term is a left-handed field Note that is a right-handed field and ok! Let’s try Lepton number violation! works too! Footnote: A Lorentz invariant mass term must link a chirally left-handed field with a chirally right handed field

  7. Construct the Majorana fields: Eigenstates of the interaction: vL and vR Mass eigenstates: Φ1 (mass mL), Φ2 (mass mR)

  8. Dirac-Majorana Mass Term with with the mass eigenstates: and mass eigenvalues: mass term for each flavor: mass matrix M In order to obtain the mass eigenstates one must diagonalize M: find unitary U with

  9. What if… mD mR 3. mR≫ mD, mL= 0: seesaw modelθ = mD/mR≪ 1 1. mL = mR = 0: pure Dirac caseθ = 45, m1=m2=mD. 2 degenerate Majorana states can be combined to form 1 Dirac state. 2. mD = 0: pure Majorana caseθ = 0, m1=mL m2=mR per neutrino flavor: one very light Majorana neutrino v1L = vL one very heavy Majorana neutrino v2L = (vR)c mD of the order of lepton masses, mR reflects scale of new physics⇒ explains small neutrino masses!

  10. Lower Limit of Neutrino Mass Super-K (atmospheric neutrinos): m2atm = 2.5 × 10-3 eV2  m(νi) ≥ 0.05 eV This sets the energy scalefor mass search!

  11. v1 v2 v3 v2 Δmsolar v1 ≲ 2 eV Δmatm v3 0 quasi-degenerate inverted hierarchy Which mass hierarchy? • Lightest neutrino mass not known • Δm2atm < 0 or >0 ? v3 Δmatm 0.05 eV v2 Δmsolar v1 ? 0 normal hierarchy

  12. β decay kinematics: - Microcalorimeters- MAC-E spectrometers 0nbb decay: 76Ge @ LNGS ´90-´03 (71.7 kg×y) 2nbb NEMO3 |mee|=0.44+0.13-0.2 eV <m>e < 2eV astrophysics: supernova time of flight measurements cosmology &structure formation 187Re 3H SuperK, SNO, OMNIS + grav.waves: potential for ~1eV sensitivity? D.N. Spergel et al: Smn < 0.69 eV (95%CL) S.W. Allen et al: Smn = 0.56 eV (best fit) Neutrino Mass Measurements Strategies ?

  13. ve Total kinetic energy Q≈ maximal kinetic energy of electron β-decay u u n p d d u d q = 2/3 + 2/3 -1/3 = 1 q = 2/3 - 1/3 -1/3 = 0 W- e-

  14. Tritium β-Decay: Mainz/Troitsk E0 = 18.6 keV dN/dE = K × F(E,Z) × p × Etot × (E0-Ee) × [ (E0-Ee)2 – mn2]1/2

  15. Problem: All experiments measured negative Δm2! Only recently solved by electrostatic spectrometers with MAC-E filter

  16. principle of an electrostatic filter with magnetic adiabatic collimation (MAC-E) adiabatic magnetic guiding of b´s along field lines in stray B-field of s.c. solenoids: Bmax = 6 T Bmin = 3×10-4 T energy analysis by static retarding E-field with varying strength: high pass filter with integral b transmission for E>qU

  17. results from the MAINZ experiment Mainz Data (1998,1999,2001)

  18. TheKArlsruhe TRItium Neutrino Experiment KATRIN ~70 m beamline, 40 s.c. solenoids

  19. Ziel: KATRIN Main Spectrometer • stainless steel vessel (Ø=10m & l=22m) on HV potential • minimisation of bg  UHV: p ≤ 10-11 mbar  „massless“ inner electrode system Commissioning 2008 UHV requirements: outgassing < 10-13 mbar l/s inner surface ~ 800m2 volume to pump ~ 1500m3

  20. 187Re b-decay: m-calorimeters E0 = 2.46 keV MIBETA experiment (Milano, Como, Trento) array of 10 AgReO4 crystals M.Sisti et al, NIM A520(2004)125 A.Nucciotti et al, NIM A520(2004)148 C. Arnaboldi et al, PRL 91, 16802 (2003) Top ~ 70-100mK

  21. fit range: 0.9 to 4 keV fit function 187Re b decay m-calorimeters Kurie plot of 6.2 ×106187Re b decay events above 700 eV dN/dE = K × F(E,Z) × p × Etot × (E0-Ee) × [ (E0-Ee)2 – mn2 ]1/2 free fit parameters: • b endpoint energy • mn2 • b spectrum normal. • pile-up amplitude • background level mn2 = -112 ± 207 ± 90 eV2 mn< 15 eV (90%CL) (2 eV in 2007?)

  22. - - e - e u e 0n - bb decay 2n - bb decay d W u W d W d n e u d n e W - e u n n e e Summenenergie der Elektronen (E/Q) Double-beta decay Lepton number violation ΔL = 2

  23. p u 0v Double Beta Decay: n d e W v = v W e d n u p Majorana-neutrino: neutrino  anti-neutrino (A,Z) (A,Z+2) + 2e- Neutrinoless Double Beta Decay only forMajorana-neutrinoandmV > 0!

  24. Phase space factor Effective neutrino mass Transition matrix element Effective neutrino mass in 0νββ-decay: Compare to β-decay: Neutrinoless Double Beta Decay

  25. Cancellation possible! Complex phases in the mixing matrix Majorana CP-Phases Dirac CP-Phase

  26. invertierte Hierarchie in eV normale Hierarchie Masse des leichtesten Neutrinos in eV

  27. Heidelberg-Moskau Collaboration, Eur.Phys.J. A12 (2001) 147 IGEX Collaboration, hep-ex/0202026, Phys. Rev. C59 (1999) 2108 HM-K IGEX 2.1 × 1023 all 90%CL 0.85 – 2.1 0v Doppel-Beta Experimente: Ergebnisse

  28. Jedoch: ein Teil der HdM Kollaboration veröffentlicht Evidenz für 0v Doppel-Beta Zerfall! ? (Q = 2039 keV für 76Ge Doppel-Beta Zerfall)

  29. Zukunft: Heidelberg Ge Initiative (MPIK Heidelberg) Phase I: 20kg angereichertes (86%) 76Ge, vgl. HDMPhase II: 100 kgJahre, 0.1 – 0.3 eVPhase III: O(1t) angereichertes 76Ge, 10meV

  30. 2v Doppelbeta mit 130Te (Q=2529 keV) 18 crystals 3x3x6 cm3 + 44 crystals 5x5x5 cm340.7 kg of TeO2 Start in 2003 Suche nach 0v Doppelbeta:T 1/20v (130Te) > 7.5 x 1023 y <mv> < 0.3 - 1. 6 eV CUORICINO 11 modules, 4 detector each, crystal dimension 5x5x5 cm3 crystal mass 790 g 4 x 11 x 0.79 = 34.76 kg of TeO2 2 modules, 9 detector each, crystal dimension 3x3x6 cm3 crystal mass 330 g 9 x 2 x 0.33 = 5.94 kg of TeO2

  31. IL PROGETTOCUORE array of 988 bolometers grouped in 19 colums with 13 flours of 4 crystals 750 kg TeO2 => 600 kg Te = 203 kg 130Te

  32. 20 sectors B(25 G) 3 m Magnetic field: 25 Gauss Gamma shield: Pure Iron (e = 18 cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since march 2004: water + boron) 4 m Able to identify e-, e+, g and a The NEMO3 detector Fréjus Underground Laboratory : 4800 m.w.e. Source: 10 kg of  isotopes cylindrical, S = 20 m2, e ~ 60 mg/cm2 Tracking detector: drift wire chamber operating in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs

  33. Transverse view Run Number: 2040 Event Number: 9732 Date: 2003-03-20 Longitudinal view Vertex emission Vertex emission Drift distance Deposited energy: E1+E2= 2088 keV Internal hypothesis: (Dt)mes –(Dt)theo = 0.22 ns Common vertex: (Dvertex) = 2.1 mm (Dvertex)// = 5.7 mm Criteria to select bb events: • 2 tracks with charge < 0 • 2 PMT, each > 200 keV • PMT-Track association • Common vertex • Internal hypothesis (external event rejection) • No other isolated PMT (g rejection) • No delayed track (214Bi rejection) bb events selection in NEMO-3 Typical bb2n event observed from 100Mo Transverse view Run Number: 2040 Event Number: 9732 Date: 2003-03-20 Longitudinal view 100Mo foil 100Mo foil Geiger plasma longitudinal propagation Scintillator + PMT

  34. bb2n measurement bb0n search bb decay isotopes in NEMO-3 detector 116Cd405 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 130Te454 g Qbb = 2529 keV External bkg measurement natTe491 g 100Mo6.914 kg Qbb = 3034 keV 82Se0.932 kg Qbb = 2995 keV Cu621 g (All the enriched isotopes produced in Russia)

  35. PRELIMINARY 100Mo 6914 g 216.4 days 4.10 kg.y Data -Log(Likelihood) bb2n Monte-Carlo Radon Monte-Carlo Data Nbb0n bb2n Monte-Carlo xbb0n= Ntot Radon Monte-Carlo Ec1+Ec2 (keV) bb0n T1/2 = 3.5 1023 V-A: T1/2(bb0n) > 3.5 1023 y (90% C.L.) Previous limit V-A: T1/2(bb0n) > 5.5 1022 y (Elegant V, Ejiri et al., 2001) 100Mo bb0n likelihood analysis 100Mo 6914 g 216.4 days 4.10 kg.y Ec1+Ec2 (keV) <mv>ee < 0.7 – 1.2 eV Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  36. Double Beta Decay: Future to t13

  37. End part 3

More Related