Neutrinos, Double Beta Decay, and Supernova Dynamics Neutrinos, Double Beta Decay, and Supernova...

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Transcript of Neutrinos, Double Beta Decay, and Supernova Dynamics Neutrinos, Double Beta Decay, and Supernova...

  • W. Bauer

    Slide 1

    Neutrinos, Double Beta Decay, and Supernova Dynamics

    Wolfgang Bauer Michigan State University

  • W. Bauer

    Slide 2

    1 meV/c2 1 eV/c2 1 keV/c2 1 MeV/c2 1 GeV/c2 1 TeV/c2

    t b τ ντ

    c s µ νµ

    u d e νe

    Mass Hierarchy

  • W. Bauer

    Slide 3

    1 GeV/c2 1 TeV/c2

    t

    b

    c

    s

    u

    d − 13 e

    + 23 e

    q

    m

    W +W −0

    1 MeV/c2

    Beta Decays β

    − : q→ q '+ − + ν; mq > mq ' + m + mν

    β + : q→ q '+ + + ν; mq > mq ' + m + mν

    Largest Suppressed Highly Suppressed

  • W. Bauer

    Slide 4

    π ±π 0

    η K ± KL 0

    KS 0

    J /ψ

    ϒ

    D

    B

    η ' ωρ

    φK *

    Composites: Mesons!

    Strong

    Electromagnetic

    Weak

  • W. Bauer

    Slide 5

    Composites: Isotopes!

  • W. Bauer

    Slide 6

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 7

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 8

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 9

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 10

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 11

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 12

    Favorite Decay Channels

  • W. Bauer

    Slide 13

    d W −

    u e−

    νe

    md > mu + me− + mνe

  • W. Bauer

    Slide 14

    d W −

    u

    e−

    νe

    d

    d u

    u n p

    mn > mp + me− + mνe

  • W. Bauer

    Slide 15

    d W −

    u

    e−

    νe

    d

    d u

    u n p

    m N Z A

    > m N−1 Z+1 A

    + m e− + mνe

    N Z A

    N −1 Z +1 A

    Already counted in atomic mass that contains Z+1 electrons

  • W. Bauer

    Slide 16

    u W +

    d

    e+

    νe

    d

    d u

    u np

    m N Z A

    > m N+1 Z−1 A

    + 2m e+ + mνe

    N Z A

    N +1 Z −1 A

    Beta+ decay: positron emission

  • W. Bauer

    Slide 17

    u W +

    d

    e− νe

    d

    d u

    u np

    m N Z A

    > m N+1 Z−1 A

    + mνe

    N Z A

    N +1 Z −1 A

    Beta+ decay: electron capture

  • W. Bauer

    Slide 18

    Favorite Decay Channels

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 19

    N

    Z

    34 82 Se34

    81 Se34 80 Se 34

    83 Se

    35 82Br35

    81Br35 80Br 35

    83Br 35 84Br

    36 81Kr 36

    82Kr 36 83Kr 36

    84Kr 36 85Kr

    34 79Se

    37 82Rb 37

    83Rb 37 84Rb 37

    85Rb 37 86Rb

    33 78As 33

    79As 33 80As 33

    81As 33 82As

  • W. Bauer

    Slide 20

    34 82 Se

    36 82Kr

    35 82Br 37

    82Rb

    38 82Sr

    39 82 Y 40

    82 Zr

    41 82Nb31

    82Ga

    32 82Ge

    33 82As

  • W. Bauer

    Slide 21

    Double Beta Decay Isotopes •  Only 12 known isotopes exhibit this

    decay •  48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd,

    128Te, 130Te, 134Xe, 136Xe, 150Nd, and 160Gd

    •  Typical lifetimes ~ 1019 years (billion times the lifetime of universe)

    •  First observed in 1986 by Michael Moe et al. for 82Se

  • W. Bauer

    Slide 22

    Life Times and Q-Values

  • W. Bauer

    Slide 23

    36 78Kr

    54 124 Xe

    N +1 -1 -2

    Z Z-1 Z-2

    Z+1

    +2 Z+2

  • W. Bauer

    Slide 24

    Double Beta+ Candidate 78Kr •  Mass(78Kr) = 77.9203 GeV

    Mass(78Se) = 77.9173 GeV Mass difference = 2.85 MeV

    •  2 EC, e+EC (threshold 1.022 MeV), and e+e+ (threshold 2.044 MeV) channels are all open (in principle!)

  • W. Bauer

    Slide 25

    Double Beta+ Candidate 78Kr •  Typical predicted half-life*  ~ 1022 years •  Need N ~ 1025 atoms of 78Kr •  Natural abundance of 78Kr = 0.35% •  Need N ~ 3•1028 atoms of natKr •  Need 0.168 kg*(3•1028)/(6•1023) =

    90 tons = 40,000 liters of natKr •  Cost: ~$200,000

    * A.Staudt, K.Muto and H.V.Klapdor-Kleingrothaus, “Nuclear matrix elements for double positron emission”, Phys. Lett. B268 (1991) 312

  • W. Bauer

    Slide 26

    Detection

    •  Gamma ray detectors for 511 keV Photons and/or photons from K-shell ionization cascades

    •  Detection of single atom of Selenium a la Ray Davis

    •  Detection of positron paths in TPC (perhaps liquid Kr, or perhaps even better high pressure gas Kr (0.1g/cm3)

  • W. Bauer

    Slide 27

    Liquid Argon TPC •  One example for

    LANNDD (Liquid Argon Neutrino and Nucleon Decay Detector)

    •  Smallest shown: V = 125 m3

    •  Design can be taken over with slight modifications (rhoAr /rhoKr = 1.65/2.41) D.B. Cline and F. Sergiampietri, “A Concept for a Scalable 2 kTon Liquid Argon TPC Detector for

    Astroparticle Physics”, http://arxiv.org/abs/astro-ph/0509410

  • W. Bauer

    Slide 28

    Previous Experiment •  tau > 0.9•1020 years •  J.M. Gavriljuk et al.,

    Phys. Atom. Nuclei 61, 1287 (1998)

  • W. Bauer

    Slide 29

    Neutrino-less Double Beta decay •  Only possible if neutrino is its own anti-particle •  Violation of Standard Model

    From: DUSEL_121306.pdf

  • W. Bauer

    Slide 30

    Current lower half-life limits

    Compiled by Steven Elliott, LANL, 2006)

  • W. Bauer

    Slide 31

    Could it be detected? •  Monte Carlo:

    5 body vs. 3 body phase space with constant or Fermi cross sections

    •  Importance sampling with N-body event generator GENBOD (F. James, CERN library)

    •  Lorentz-invariant Fermi phase space •  Respects all conservation laws (energy,

    momentum) and uses proper reaction Q-value

  • W. Bauer

    Slide 32

    Monte Carlo Events Neutrino Positron Recoil Nucleus

    3d momentum space event displays in cm-system

  • W. Bauer

    Slide 33

    Positron Energy distributions •  Monte Carlo:

    5 body vs. 3 body phase space with constant or Fermi cross sections

    •  Here: 106 events •  More realistic:

    101-102 events

  • W. Bauer

    Slide 34

    Coincidence Counts •  In 0nu case the

    daughter nucleus receives almost vanishing recoil energy

    •  Clear signal •  (Note: not true for

    recoil momentum of daughter nucleus)

  • W. Bauer

    Slide 35

    Background: 2 simult. Beta+ decays •  Very rare •  But we are dealing

    a very rare signal!