Application of neutrino spectrometry

1) Solar neutrino detection

2) Supernovae neutrino detection

3) Cosmic and atmospheric neutrino detection

4) Neutrino oscillation studies

Supernovae 1987A remnantNeutrino detector ANTARESat Mediterranean See

Sun from SOHO probe

5) Detection of neutrinos from Earth interior

6) Relict neutrino detection

Study of solar neutrinos

neutrino energy [MeV]

Neu

trin

o fl

uen

ce [

cm-2s-1

]

Spectrum of solar neutrinos calculated by J. Bahcalla

Present information:1) Solar neutrino are produced 2) Significant difference between prediction and observation → sign of new physics (neutrino oscillations)

Future information based on neutrinos:1) Accurate sizes of Sun central regions, where fusion reactions runs2) Present picture of Sun interior (photons travel through sun long time) – prediction of future Sun behavior3) Temperature of central regions of Sun 4) Ratios between different types of fusion reactions

Sun from SOHO probe

Big amount of electron neutrino is produced during pp and CNO cycle

4p → 4He + 2e+ + 2νe

Study of supernovae neutrinos

Final stage of massive star – collapse and supernovae explosionLarge 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

Relation between neutrino energy and time of its arrival

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 lifetimePossible future information (we are waiting on near supernovae): Confirmation of models of supernovae explosion Properties of hot and very dense matter 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 …)

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

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

Distribution of directions, from which single neutrinos came – random distribution –Point like sources were not found – also correlation with gamma bursts were not found

Spectrum of neutrinos agrees with predictionfor atmospheric neutrinos

Results of AMANDA detector

Nebula NGC6543(Hubble telescope)

Active galaxy

Studies of neutrino oscillation

2

1e

cossin

sincos

)L/Em27.1(sin2sin)P( 222e

As example – oscillation of anti νμ and anti νe:

Probability of muon antineutrino to electron is:

where Δm2 = |m12 – m2

2| [eV2], L – distance at meters [m] Eν – neutrino energy [MeV]

Neutrino wave function is mixture of different states (νe, νμ, ντ) .

d

Probability, that at distance d we find anti νμ is and anti νe :)(P )(P e

Oscillation were observed: 1) Solar neutrinos (large distances) 2) Nuclear power station 3) Secondary cosmic rays 4) Accelerator - detector

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

Solar neutrinos

Derivation of Δm2 (νe ↔ νμ) Δm2 ~ 7(4)∙10-5 eV2

Relation betweenΔm2 and θ values

Experiment GALEX

Detector KAMLAND Measured and simulated spectrumof antineutrinos

Oscillation data measured using different reactors

Measurement of reactor antineutrino oscillation

Δm2 =7,9(6)∙10-5 eV2νμ ↔ νeDetection of antineutrino

Time variation given by changes of nuclear reactors power

Secondary cosmic ray

νμ ↔ ντ Δm2 =(1-3)∙10-3 eV2

Accelerator – detector experiment

K2K experiment – observation of 108 neutrinos – prediction of 151(11) neutrinos

νe - isotropic distributionνμ - úbytek

The best fit with oscillation

Neutrino spectrum detectedby K2K experiment

Region of suitable Δm2 a sin22θ values

Angular distribution of cosmicneutrinos from Kamiokande

Geoneutrinos

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

geoantineutrinos

reactor antineutrinos

background

13C(α,n)16O

Project KamLAND – study of antineutrino oscillations by means of reactor

Antineutrinos from project KamLAND(corrected on oscillations)

Larger detector farer from reactors makes possible study of antineutrinos with such accuracy, which is needed for some geophysical models exclusion

Thermal flow: Total ~ 40 TW radionuclides ~ 19 TW(U,Th,K)

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:

iiee 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+ + e- Electron 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