1 MPI for Biological Cybernetics 2 Stanford University 3 University Hospital Tuebingen
Search for the Cosmic Neutrino Background and the Nuclear Beta Decay. Amand Faessler University of...
Transcript of Search for the Cosmic Neutrino Background and the Nuclear Beta Decay. Amand Faessler University of...
Search for the Cosmic Neutrino Background and the
Nuclear Beta Decay.
Amand FaesslerUniversity of Tuebingen
Germany
Publication: Amand Faessler, Rastislav Hodak, Sergey Kovalenko, Fedor Simkovic:
arXiv: 1304.5632 [nucl-th] 20. April 2013.
Cosmic Microwave Background Radiation
(Photons in the Maximum 2 mm)
Decoupling of the photons from matter about 300 000 years after the Big Bang, when the electrons are captured by the protons and He4 nuclei and the
universe gets neutral. Photons move freely. Today: ~550 Photons /cm3 (~340 Neutrinos/cm3)
Planck Satellite Temperature FluctuationsComic Microwave Background (Release March 21. 2013)
e(f) = (8ph/c3) f3df/[exp(hf/kBT)-1][Energy/Volume]
Neutrino Decoupling and Cosmic Neutrino Background
For massless-massive Neutrinos:
Estimate of Neutrino Decoupling
Universe Expansion rate: H=(da/dt)/a; a ~ 1/T; (today, Planck) H = 67km/(sec*Mpc)
~ n Interaction rate: = G ne-e+<svrelative>
Neutrino Decoupling
G/H = ( kB T/ 1MeV)3 ~ 1
T(Neutrinos)decoupl ~ 1MeV ~ 1010 Kelvin;
today: Tn = 1.95 K
Time after Big Bang: 1 Second
(Energy=Mass)-Density of the Universe
log r
a(t)~1/T
Radiation dominated: r ~ 1/a4 ~ =Stefan-Boltzmann
Matter dominated: r ~ 1/a3 ~ T3
Dark Energy
1/Temp1 MeV1sec n
dec.
1 eV3x104y today
3000 K300 000 y
g dec.
8x109 y g 2.7255 Kn 1.95 K
Mass of the Electron Neutrino?Tritium decay (Mainz + Troisk)
With:
Hamburg, March 3. 2008.
Measurement of the upper Limit of the Neutrino Mass in Mainz: mn < 2.2 eV 95% C.L.
Kurie-Plot
Q = 18.562 keV
mn 2>0 mn2 <0 Electron Energy
Eur. Phys. J. C40 (2005) 447
Search for Cosmic Neutrino Background CnB by Beta decay: Tritium
Kurie-Plot of Beta and induced Beta Decay: n(CB) + 3H(1/2+) 3He (1/2+) + e-
Electron Energy
2xNeutrino Masses
Emitted electron
Q = 18.562 keV
Infinite good resolution
Resolution Mainz: 4 eV mn < 2.3 eV
Resolution KATRIN: 0.93 eV mn < 0.2 eV 90% C. L.
Fit parameters: mn
2 and Q value meVAdditional fit: only
intensity of CnB
Neutrino Capture: n(relic) + 3H 3He + e-
20 mg(eff) of Tritium 2x1018 T2-Molecules: Nncapture(KATRIN) = 1.7x10-6 nn/<nn> [year-1]
Every 590 000 years a count!! for <nn> = 56 cm-3
Kurie-Plot
Electron Energy
2xNeutrino Masses
Emitted electron
Resolution KATRIN: 0.93 eV mn < 0.2 eV 90% C.L.
Fit parameters: mn
2 and Q value meVAdditional fit: only
intensity of CnB
Two Problems1. Number of Events with average Neutrino Density
of nne = 56 [ Electron-Neutrinos/cm-3] Katrin: 1 Count in 590 000 Years Gravitational Clustering of Neutrinos!!!???2. Energy Resolution (KATRIN) DE ~ 0.93 eV
Gravitational Clustering of NeutrinosR.Lazauskas,P. Vogel and C.Volpe, J. Phys.g. 35 (2008) 025001;
Light neutrinos: Gravitate only on 50 Mpc (Galaxy Cluster) scale: nn/<nn> ~ nb/<nb> ~ 103 – 104; <nb>= 0.22 10-6 cm-3
A. Ringwald and Y. Wong: Vlasov trajectory simulations. Clustering on Galactic Scale possible (30 kpc to 1 Mpc)
nn/<nn> = nb/<nb> ~ 106 ; (R = 30 kpc)
Nncapture(KATRIN) = 1.7x10-6 nn/<nn> (year-1)= 1.7 [counts per year]
Effective Tritium Source: 20 microgram 2 milligramNncapture(KATRIN*) = 1.7x10-4 nn/<nn> (year-1)= 170 [counts peryear];
See also: B. Monreal, J. A. Formaggio, Phys. Rev. D80 (2009) 051301 „Relativistic cyclotron radiation detection of tritium decay electrons“
Summary 1• The Cosmic Microwave Background
allows to study the Universe 300 000 year after the BB.
• The Cosmic Neutrino Background 1 sec after the Big Bang (BB): Tn(today) = 1.95 Kelvin
2xNeutrino Masses
Emitted electron
Kurie-Plot
Electron Energy
Summary 21. Average Density: nne = 56 [ Electron-Neutrinos/cm-3] Katrin: 1 Count in 590 000 Years Gravitational Clustering of Neutrinos nn/<nn> < 106
1.7 counts per year (2 milligram 3H 170 per year)2. Measure only an upper limit of nn
THE END