Transcript Search for the Cosmic Neutrino Background - uni

Search for the Cosmic
Neutrino Background and the
Nuclear Beta Decay (KATRIN).
Amand Faessler,
Rastislav Hodak, Sergey Kovalenko,
Fedor Simkovic;
Bad Honnef 24. April 2014
Publication: arXiv: 1304.5632 [nucl-th]
11. Dec. 2013 and accepted by
EPJ Web of Conferences vol. 71.
Cosmic Microwave
Background Radiation
(Photons in the Maximum 2 mm)
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 and the
universe gets neutral. Photons move freely.
Microwave Background Radiation
Penzias and Wilson;
BellTelephon
Nobel Price 1978
Radiation follows exactly the Planck Black Body
formula with T = 2.7255(6) Kelvin in all directions.
Planck Satellite Temperature Fluctuations
Comic Microwave Background (Release March 21. 2013)
One sees the „hot“ spots as
large as they have to be. Thus
Universe flat: WMAP: 2%;
Planck Satellite: ~ 0.1 %.
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 at Photon Decoupling 380 000 Years
after Big Bang lead to Fluctuations at 1.5 to 3 angular
Degrees.
Gravitational Waves are Quadrupole
Oscillations of Space not in Space.
1.5 to 4 degrees;
ℓ = 40 𝑡𝑜 110
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
(Energy=Mass)-Density of the Universe
log r
Radiation dominated: r ~ 1/a4 ~ 𝑇4=Stefan-Boltzmann
Matter dominated: r ~ 1/a3 ~ T3
Dark Energy
a(t)~1/T
1 MeV 1 eV
3000 K
~1sec 5x104y 380 000 y
n dec.
g dec.
8x109 y
g 2.7255 K
n 1.95 K
1/Temp
today
Upper Limit of the Neutrino Mass in Mainz+Troitsk:
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
Planck Satellite (CMB, Lensing, BAO):
𝑗=1,2,3 𝑚𝜈𝑗
≤ 0.26 [𝑒𝑉]; 95% 𝐶. 𝐿.
BAO = Baryon Acoustic Ocscillations
How can one detect the
Cosmic Neutrino Background?
1. Anihilation of extreme high energy neutrinos
with low energy relic neutrinos into Z0 burst
above the Greisen-Zatsepin-Kuzmin cut-off.
2. Free magnetic floating divided cylinder with
neutrino absorber and neutrino non-absorbing
material.
3. Electron-Neutrino capture on Tritium (KATRIN).
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:
Number of Events with average Electron-Neutrino
Density of nen = 56 [Electron-Neutrinos/cm3]
KATRIN: 1 Count in 590 000 Years
Gravitational Clustering of Cosmic
Background Neutrinos in our Galaxy.
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.
Only 36% have
not scattered
Source
Beam Magnetic Field
Column length d
Base 1 cm2
3.6 Tesla
Tritium Gas
Number of Tritium-Atoms in Column d = Column-Density
Optimal Column 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  spectrometer-diam. = 97 meters
A giant on trip
KATRIN
Spectrometer tank
on the way from
the Rhine to the FZ
Karslsruhe
Compress the electron cyclotron beam of
diameter 80 cm to the diameter
= 8 cm of the transport channel by
an increase 0.036  3.6 Tesla magnetic field
Beat the magnetic mirror by
accelerating the electrons by a positive
Voltage of the transport channel.
In the start of the spectrometer one
must be back to earth potential.
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
𝐸𝑖𝑝
L = |r× 𝐩| ∝ m = const ∝
𝐵𝑖
DE !=1 eV= Efp =
𝐵𝑓
𝐵𝑖
=
3 𝐺𝑎𝑢𝑠𝑠
Eip=
360 𝐺𝑎𝑢𝑠𝑠
𝐸𝑓𝑝
𝐵𝑓
Eip;
Eip = 120 eV; of Q = 18.562 keV
Pperpendicular
Beam direction
pparallel
DW/(2p) = 0.005 = 0.5 %
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).
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
and 20 micrograms Tritium  1.7 counts per year.
(2 milligram 3H 170 counts per year. Impossible ?)
2. Measure only an upper limit of nn
Kurie-Plot
Emitted
electron
ENDE
Electron Energy
2xNeutrino Masses