Transcript Search for the Cosmic Neutrino Background - uni

Can we look back to the
Origin of our Universe?
Cosmic Photon, Neutrino and
Gravitational Wave Backgrounds.
Amand Faessler,
Erice September 2014
With thanks to: Rastislav Hodak,
Sergey Kovalenko, Fedor Simkovic;
Publication: arXiv: 1304.5632 [nucl-th];
arXiv: 1407.6504 [nucl-th] July 2014 and accepted by
EPJ Web of Conferences vol. 71; to be published J. Phys. G 2014.
1) Cosmic Microwave Background Radiation
2) Cosmic Neutrino Background
3) Cosmic Gravitational Wave Background
1) Decoupling of the photons from matter about
380 000 years after the Big Bang, when the electrons
are captured by the protons and He4 nuclei at a
Temp. of about 3000 Kelvin.
The universe was then neutral. Photons move freely.
Planck Satellite Temperature Fluctuations
Comic Microwave Background (Release March 21. 2013)
On 18. March 2014 the BICEP2
Collaboration published in the arXiv:
1403.3985v2 [astro-ph.CO]
Fingerprint of the Gravitational Waves
of the Inflationary Expansion
of the Big Bang in the
Cosmic Background Radiation.
Gravitational Waves are Quadrupole
Oscillations of Space not in Space.
BICEP2 Detector
at the South-Pole
1.5 to 4 degrees;
ℓ = 40 𝑡𝑜 110
2) Estimate of Neutrino Decoupling
Universe Expansion rate: H=(da/dt)/a
~ n Interaction rate: G= ne-e+<svrelative>
H=
8π𝐺ρ𝑡𝑜𝑡𝑎𝑙/3= O( T2) [1/time]
StefanBoltzmann
G ~ (1/a3) <GF2 p2 c=1> ~ T3 <GF2 T2c=1> ~ GF2 T5 [1/time]
with: Temperature = T ~ 1/a = 1/(length scale); ℎ𝑏𝑎𝑟 = h/(2p) = c = 1
How can one detect the
Cosmic Neutrino Background?
Electron-Neutrino
capture on Tritium.
3. 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-+nc
e
Neutrino Capture: n(relic) + 3H 3He + e-
20 mg(eff) of Tritium  2x1018 T2-Molecules:
Nncapture(KATRIN) = 1.7x10-6 nen/<nen> [year-1]
Every 590 000 years a count! for <nen> = 56 cm-3
Problem: 56 e-Neutrinos cm-3 too small
• Gravitational Clustering of Neutrinos
estimated by Y. Wong, P. Vogel et al.:
nne(Galaxy) = 106*<nne> = 56 000 000 cm-3
1.7 counts per year
Increase th source strength: 20 micrograms  2 milligrams
170 counts per year  every second day a count
Speakers of KATRIN:
Guido Drexlin and Christian Weinheimer
20 microgram 
2 milligram Tritium
• Such an Increase of the
Tritium Source Intensity is
with a KATRIN Type
Spectrometer is difficult,
if not impossible!
Three important Requirements:
1) The Tritium Decay Electrons are not allowed
to scatter with the Tritium Gas.
2) The Magnetic Flux must be conserved in the
whole Detection System.
3) The Energy resolution must be of the order
of 1 eV.
1) The decay electrons should not
scatter by the Tritium gas.
Source
Only 36% have
not scattered
Beam Magnetic Field
3.6 Tesla
Tritium Gas
Optimal Density slightly below r*dfree /2
Troitsk: 30%; Mainz: 40%; KATRIN: 90%
2) Conservation of Magnetic Flux
If one cant increase the intensity per area, increase the
area by factor 100 from 53 cm2 to 5000 cm2.
Magnetic Flux:
(Ai=5000 cm2) x (Bi=3.6 Tesla) =
18 000 Tesla cm2 = Af x (3 Gauss);
Af = 6 000 m2  diameter = 97 meters
3) Energy resolution of DE~ 1 eV
Energy resolution: Ef(perpend.) = Efp = DE
Angular Momentum of the Spiraling
Electrons must be conserved
Energy resolution: Ef(perpend.) = Efp = DE = 1 eV
L = |r× 𝐩| ∝ m = const ∝
L~
12 000 𝑒𝑉
[
]i
36 000 𝐺𝑎𝑢𝑠𝑠
=[
1 𝑒𝑉
]𝑓
𝐵𝑓
𝐸𝑖𝑝
𝐵𝑖
=
𝐸𝑓𝑝
𝐵𝑓
 Bf = 3 Gauss
20 microgram 
2 milligram Tritium
• Such an Increase of the Tritium
Source Intensity with a KATRIN
Type Spectrometer is difficult,
if not impossible.
Summary 1
• The Cosmic Microwave Background allows to
study the Universe
380 000 years after the BB.
• The Cosmic Neutrino Background
1 sec after the Big Bang (BB).
• The Cosmic Background of Gravitational Waves
10-31 Seconds in the Big Bang
Summary 2: Cosmic Neutrino Background
1. Average Density: nne = 56 [ Electron-Neutrinos/cm-3]
Katrin: 1 Count in 590 000 Years
Gravitational Clustering of Neutrinos nn/<nn> < 106
and 20 micrograms Tritium  1.7 counts per year.
(2 milligram 3H 170 counts per year. Impossible ?)
THE END
2. Measure only an upper limit of nn
Kurie-Plot
Emitted
electron
Electron Energy
2xNeutrino Masses
Cyclotron Radiation Detection of Tritium Decay
Electrons. Phys. Rev. D80 (2009) 051301