1 / 33

IS THE NEUTRINO A MAJORANA OR A DIRAC PARTICLE ?

IS THE NEUTRINO A MAJORANA OR A DIRAC PARTICLE ?. Ettore Fiorini, Bologna June 17 2005. n=n - or n ≠ n - Lepton number conservation or violation Has neutrino a finite mass 100 % chirality. n n -    . The Standard Model

faye
Télécharger la présentation

IS THE NEUTRINO A MAJORANA OR A DIRAC PARTICLE ?

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. IS THE NEUTRINO A MAJORANA OR A DIRAC PARTICLE ? Ettore Fiorini, Bologna June 17 2005 n=n-or n≠n- Lepton number conservation or violation Has neutrino a finite mass 100 % chirality n n-    

  2. The Standard Model ne (nֿe ) nm(nֿm) nt(nֿ t) Flavor conservation or violation Neutrino oscillations need mn≠ 0 ne nm ne nt

  3. Neutrino oscillations have been observed with solar, atmosperic and reactor neutrinos

  4. ATMOSPHERIC NEUTRINOS Superkamiokande and MACRO Reactor and long baseline experiments Neutrino factories

  5. But oscillation experiments only indicate that m n2 ≠ 0to determine < m n > => double beta decay 1. (A,Z) => (A,Z+2) + 2 e- + 2 ne¯2. (A,Z) => (A,Z+2) + 2 e- + c ( …2,3 c)3. (A,Z) => (A,Z+2) + 2 e-

  6. - - e - e u e d n W e u W n e d W d u d W - e u 2n - bb decay n n e e 0n - bb decay Neutrinoless bb decay

  7. Neutrinoless bb decay would imply a non zero effective majorana neutrino mass as indicated by oscillation experiments

  8. detector e- e- source e- e- detector SourceDetector Experimental approaches Geochemical experimentsi82Se = > 82Kr, 96Zr = > 96Mo (?) , 128Te = > 128Xe (non confirmed), 130Te = > 130TeRadiochemical experiments238U = > 238Pu (non confirmed) Direct experiments Source = detector (calorimetric) Sourcedetector

  9. heat bath Thermal sensor absorber crystal Incident particle Cryogenic detectors

  10. DE @ 5 keV ~100 mk ~ 1 mg <1 eV ~ 5 eV @ 2 MeV ~10 mk ~ 1 kg <10 eV ~ keV

  11. Experim Isotope t1/20n (y) m*ee (eV) Range mee Heidelberg – Moscow 2001 > 1.9  1025 < 0.35 < 0.3 – 2.5 76Ge IGEX 2002 > 1.57  1025 < 0.38 < 0.3 – 2.5 Mi DBD – n 2002 130Te > 2.1  1023 < 1.5 < 0.9 – 2.1 Bernatowicz et al. 1993 (GEO) 128Tegeo > 7.7  1024 < 1.0 < 1.0 – 4.4 Belli et al. 2003 136Xe > 1.2  1024 < 1.0 < 0.8 – 2.4 Bizzeti et al. 2003 116Cd > 1.7  1023 < 1.7 < 1.6 – 5.5 Ejiri et al. 2001 100Mo > 5.5  1022 < 4.8 < 1.4 - 256 Osawa I. et al. 2002 48Ca > 1.8  1022 < 6.0 * Staudt, Muto, Klapdor-Kleingrothaus Europh. Lett 13 (1990) 31 Recent experiments on bb0n The “Klapdor ” effect =>T= 1.2 x 1025 a => <mn > ~ 0.44 eV

  12. Two new experiments NEMO III e CUORICINO

  13. Searches with thermal detectors CUORE R&D (Hall C) CUORE (Hall A) Cuoricino (Hall A)

  14. Crescita della massa dei bolometri total mass [kg] year

  15. Search for the 2b|on in 130Te (Q=2529 keV) and other rare events • At Hall A in the Laboratori Nazionali del Gran Sasso (LNGS) • 18 crystals 3x3x6 cm3 + 44 crystals 5x5x5 cm3 = 40.7 kg of TeO2 • Operation started in the beginning of 2003 => ~ 4 months • Background .18±.01 c /kev/ kg/ a • T 1/20n (130Te) > 1.8x 1024 y <mn> .2 -1. 1 Klapdor 0.1 – 0.9 2modules, 9detector each, crystal dimension3x3x6 cm3 crystal mass330 g 9 x 2 x 0.33 = 5.94 kg of TeO2 11modules, 4detector each, crystal dimension5x5x5 cm3 crystal mass790 g 4 x 11 x 0.79 = 34.76 kg of TeO2

  16. Present Cuoricino region Arnaboldi et al., submitted to PRL, hep-ex/0501034(2005). Possible evidence (best value 0.39 eV) With the same matrix elements the Cuoricino limit is 0.53 eV “quasi” degeneracy m1 m2  m3 Inverse hierarchy m212= m2atm Direct hierarchy m212= m2sol Cosmological disfavoured region (WMAP) Feruglio F. , Strumia A. , Vissani F. hep-ph/0201291

  17. 750 kg TeO2 => 600 kg Te => 203 kg 130Te The CUOREproject 988bolometers in19 colums od 13 flors of 4crystals Sensitivity of a few tens of eV

  18. CONCLUSIONS The discovery of neutrino oscillations to which Masatoshi contributed so much exists and Dm2≠ 0 We need to determine the Majorana nature of the neutrinoand the absolute value of <mn> Neutrinoless double beta decay would indicate not only lepton number violation , but also<mn > ≠ 0 This process has been indicated by an experiment (Klapdor) with a value of ~0.44 eV but not confirmed by CUORICINO Future experiments on neutrinoless double beta decay will allow to reach the sensitivity predicted by oscillations Their peculiar multiplinarity involves nuclear and e subnuclear physics , astrophysics , radioactivity, material science, geochronology etc

More Related