Search for the Cosmic Neutrino Background and the Nuclear Beta Decay (KATRIN).

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.

Penzias and Wilson;BellTelephon

Nobel Price 1978

Microwave Background Radiation

Planck Satellite Temperature FluctuationsComic Microwave Background (March 21. 2013)

6

Curvature of the Univers

flat

xx x

1 1 1

WMAP 2002 :

1.00 0.02

We know the size of the hot spots.

Black body radiation.

Temperature adjusted

(pdg 2012):T=2.7255(6) K

Experiment

Microwave Background Radiation

T = 2.7255(6) Kelvin

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{8 p G rtotal /3} = \sqrt{8 p r/(3 MPlanck2)}[1/time]

G ~ T3 <GF2 p2 c=1> = T3 GF

2 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

T(Photons)decoupling = 3000 Kelvin; today: 2.7255 K Time(Photons)decoupling = 300 000 years

Below T = 1 MeV:

(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

Hamburg, March 3. 2008.

Tranformation from Mass to Flavor Eigenstates

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

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

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 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 milligramNncapture(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).

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

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

ENDE