Application of neutrino spectrometry
1) Solar neutrino detection
2) Supernovae neutrino detection
3) Cosmic and atmospheric neutrino detection
4) Neutrino oscillation studies
5) Detection of neutrinos from Earth interior
6) Relict neutrino detection
Sun from SOHO probe
Neutrino detector ANTARES
at Mediterranean See
Supernovae 1987A remnant
Study of solar neutrinos
Big amount of electron neutrino is produced during pp and
CNO cycle
4p → 4He + 2e+ + 2νe
Present information:
1) Solar neutrino are produced
2) Significant difference between prediction
and observation → sign of new physics
(neutrino oscillations)
Neutrino fluence [cm-2s-1]
Future information based on neutrinos:
1) Accurate sizes of Sun central regions,
where fusion reactions runs
2) Present picture of Sun interior (photons
travel through sun long time) –
prediction of future Sun behavior
3) Temperature of central regions of Sun
4) Ratios between different types of fusion
reactions
Sun from SOHO probe
neutrino energy [MeV]
Spectrum of solar neutrinos calculated by J. Bahcalla
Study of supernovae neutrinos
Final stage of massive star – collapse and supernovae explosion
Large part of energy releases in the form of neutrino during two phases:
1) Beginning – during neutron creation by electron capture only electron neutrino:
p + e- → n + νe
2) All types of neutrino and antineutrino with statistical distribution (1/6 on one
type) with mean energy 10 – 15 MeV. Energy spectrum → Fermi distribution
kT ≈ 3 – 6 MeV
Supernovae SN1987A
Distance of 150 000 light years
Present information (supernovae SN1987A):
Confirmation of neutrino creation
Ordinary agreement with assumption
Closeness of neutrino velocity to light velocity,
limitation on neutrino rest mass
Determination of limitation on neutrino lifetime
Possible future information (we are waiting on near supernovae):
Confirmation of models of supernovae explosion
Relation between neutrino
Properties of hot and very dense matter
energy and time of its arrival
Observation of supernovae shielded by galactic matter
Cosmic ray neutrinos
Primary component: particle with high energy (up to ~ 1011 GeV – present accelerators
~ 104 GeV), protons and nuclei are the biggest part, also neutrinos and antineutrins
νe, νμ a ντ are present. Isotropic distribution – they come from all directions
Origin: more distant undistinguishable sources (supernovae, active galaxy nuclei,
collapsing objects …)
Secondary component:
Collisions of cosmic ray particles and nuclei with atmospheric
nuclei → many hadrons → many mesons π among them:
π + → μ+ + νμ
π - → μ- + anti -νμ
└→ e+ + νe + anti-νμ
└→ e- + anti-νe + νμ
Intensive source of neutrino and antineutrino νμ and νe
ratio between numbers of νμ and νe is R(νμ/νe) = 2
also intensive source of muons
Atmospheric shower
Possible future information:
Information about processes and sources with big amount of energy
(gamma burst sources)
Not distorted data about region covered by dense clouds of matter
Neutrino path is not influenced by magnetic fields and they are not absorbed
Study of nature of cosmic phenomena
Results of AMANDA detector
Nebula NGC6543
(Hubble telescope)
Active galaxy
Spectrum of neutrinos agrees with prediction
for atmospheric neutrinos
Distribution of directions, from which single neutrinos came – random distribution –
Point like sources were not found – also correlation with gamma bursts were not found
Studies of neutrino oscillation
Neutrino wave function is mixture of different states (νe, νμ, ντ) .
As example – oscillation of anti νμ and anti νe:
 e   cos  sin   1 
   
   sin  cos   
 2 
  
Probability of muon antineutrino to electron is:
P(   e )  sin 2 2  sin 2 (1.27  m2  L/E )
where
Δm2 = |m12 – m22| [eV2], L – distance at meters [m]
Eν – neutrino energy [MeV]
Probability, that at distance d we find
anti νμ is P(  ) and anti νe P( e ) :
d
Oscillation were observed: 1) Solar neutrinos (large distances)
2) Nuclear power station
3) Secondary cosmic rays
4) Accelerator - detector
Solar neutrinos
Experiment
EMIN
[MeV]
Experiment
[SNU]
Model
[SNU]
Exp./Mod.
Kamiokande
7
0.47(2)
1.00(17)
0.47
Homestake (Cl)
0.8
2.56(23)
7.7(12)
0.33
GALEX
0.2
74(7)
129(8)
0.57
SAGE
0.2
75(8)
129(8)
0.58
Derivation of Δm2 (νe ↔ νμ) Δm2 ~ 7(4)∙10-5 eV2
Relation between
Δm2 and θ values
Experiment GALEX
Measurement of reactor antineutrino oscillation
Detection of antineutrino νμ ↔ νe Δm2 =7,9(6)∙10-5 eV2
Time variation given by
changes of nuclear reactors
power
Oscillation data measured using
different reactors
Detector KAMLAND
Measured and simulated spectrum
of antineutrinos
Secondary cosmic ray
Angular distribution of cosmic
neutrinos from Kamiokande
νe - isotropic distribution
νμ - úbytek
νμ ↔ ντ
Δm2 =(1-3)∙10-3 eV2
Accelerator – detector experiment
K2K experiment – observation of 108 neutrinos – prediction of 151(11) neutrinos
Neutrino spectrum detected
by K2K experiment
The best fit
with oscillation
Region of suitable
Δm2 a sin22θ values
Geoneutrinos
Project KamLAND – study of antineutrino oscillations by means of reactor
Antineutrinos from 238U and 232Th decay
Decay of 238U and 232Th impeachable for hot earth core and plate tectonics
First observation – project KamLAND:
4 – 40 detected geoantineutrinos
Agree with model predictions about amount of
uranium and thorium in earth crust and core
13C(α,n)16O
reactor
antineutrinos
background geoantineutrinos
Antineutrinos from project KamLAND
(corrected on oscillations)
Thermal flow:
Total
~ 40 TW
radionuclides ~ 19 TW
(U,Th,K)
Larger detector farer from reactors makes
possible study of antineutrinos with such
accuracy, which is needed for some geophysical
models exclusion
Relict neutrinos
are produced during early stage of universe t ~ 1s (t ~ 300 000 years for relict photons), present
temperature of neutrinos is T ≈ 1,9 K (photons T ≈ 3,1 K)
For energies E > 1 MeV different types of neutrinos are in the equilibrium:
e   e    i  i
where i = e, μ, τ
For lower energies neutrinos do not interact with rest of matter – freeze out occurs
Very low energy → very big problems with detection
Possibility of detection (only hypothetical up to now):
1) Processes, which do not need energy – neutrino initiates beta decay of nucleus:
νe + n → p+ + eElectron energy > decay energy of nucleus → peak in the electron spectrum under end of Fermi
graph (very weak). Measurement as during neutrino mass studies – necessity to find proper nuclei
and transitions, number of decays initiated by relict neutrinos was should be not negligible.
Necessity to improve parameters of electron spectrometers. Problems with the natural background.
2) Interaction of accelerated particles – energy is delivered by accelerated particles. Choice of proper
parameters for sufficient probability of interaction – problem with background, necessity of high
intensity and stability of accelerator beam.
3) Interaction of very energetic neutrinos of cosmic rays:
such Eν, that centre of mass energy is equal to rest mass of Z boson during collision with relict
neutrino MZ = 100 GeV (1012 – 1016 GeV – real value depends on neutrino mass) → resonce
increasing of interactions with relict neutrinos occurs → minimum in the energy spectrum of high
energy of cosmic neutrinos