Search for the Cosmic Neutrino Background - uni

Report
Search for the Cosmic
Neutrino Background and the
Nuclear Beta Decay (KATRIN).
Amand Faessler
University 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.
Microwave Background Radiation
Penzias and Wilson;
BellTelephon
Nobel Price 1978
Planck Satellite Temperature Fluctuations
Comic Microwave Background (March 21. 2013)
We know the
size of the
hot spots.
Curvature of the
Univers
flat
x
x
 1
 1
x
WMAP 2002 :
  1.00  0.02
 1
6
Microwave Background Radiation
Experiment
T = 2.7255(6) Kelvin
Black body
radiation.
Temperature
adjusted
(pdg 2012):
T=2.7255(6) K
Planck‘s Black Body Radiation
Neutrino Decoupling and
Cosmic Neutrino Background
For massless-massive Neutrinos:
Estimate of Neutrino Decoupling
Universe Expansion rate: H=(da/dt)/a
~ n Interaction rate: G ne-e+<svrelative>
H = \sqrt{8p G rtotal /3} = \sqrt{8 p r/(3 MPlanck2)}[1/time]
G ~ T3 <GF2 p2 c=1> = T3 GF2 T2 = GF2 T5 [Energy = 1/time]
hbar = h/(2p) = c = 1
Neutrino Decoupling
G/H = ( kB T/ 1MeV)3 ~ 1
T(Neutrinos)decoupl ~ 1MeV ~ 1010 Kelvin; today: 1.95 K
Time after Big Bang: 1 Second
Below T = 1 MeV:
T(Photons)decoupling = 3000 Kelvin; today: 2.7255 K
Time(Photons)decoupling = 300 000 years
(Energy=Mass)-Density of the Universe
log r
Radiation dominated: r ~ 1/a4 ~ 4=Stefan-Boltzmann
Matter dominated: r ~ 1/a3 ~ T3
Dark Energy
a(t)~1/T
1 MeV 1 eV
3000 K
1sec 3x104y 300 000 y
n dec.
g dec.
8x109 y
g 2.7255 K
n 1.95 K
1/Temp
today
Tranformation from Mass
to Flavor Eigenstates
Hamburg, March 3. 2008.
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
Eur. Phys. J.
C40 (2005) 447
mn
2>0
mn2 <0
Q = 18.562 keV
Electron Energy
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-
Infinite good
resolution
Q = 18.562 keV
Resolution Mainz: 4 eV
 mn < 2.3 eV
Emitted
electron
Resolution KATRIN: 0.93 eV
 mn < 0.2 eV 90% C. L.
Fit parameters:
mn2 and Q value meV
Electron Energy
2xNeutrino
Masses
Additional fit: only
intensity of CnB
Tritium Beta Decay: 3H 3He+e-+nce
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
Two Problems
1. 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
Kurie-Plot
Emitted
electron
Resolution KATRIN: 0.93 eV
 mn < 0.2 eV 90% C.L.
Fit parameters:
mn2 and Q value meV
Electron Energy
2xNeutrino
Masses
Additional fit: only
intensity of CnB
Gravitational Clustering of Neutrinos
R.Lazauskas,P. Vogel and C.Volpe, J. Phys.g. 35 (2008) 025001;
Light neutrinos: Gravitate only on 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
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 milligram
Nncapture(KATRIN*) = 1.7x10-4 nn/<nn> (year-1)
= 170 [counts per year]
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.
• Extremly difficult to detect: Small Cross
Section and low Density 56 n‘s/cm3 and low
Energies (1.95 Kelvin = 2x10-4 eV).
Summary 2
1. 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
Kurie-Plot
Emitted
electron
Resolution KATRIN: 0.93 eV
 mn < 0.2 eV 90% C.L.
Fit parameters:
mn2 and Q value meV
ENDE
Electron Energy
2xNeutrino
Masses
Additional fit: only
intensity of CnB

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