Usage of electron spectrometry

A) Studies of nuclear structure, decays and reactions

1) Study of conversion electrons 2) Study of electrons and positrons from beta decays 3) Study of Auger electrons 4) Determination of electron neutrino mass 5) Study of di-lepton pairs at high-energy physics

B) Application

1) Spectroskopy of electron energy losses with high resolution 2) Measurement of atomic level widths and binding energy of electrons 3) Study of molecular bonding from shifts of energies of conversion electron lines

Electron spectrum: 1) Continuous – from beta decay bremsstrahlung ... 2) Discrete – conversion, Auger electrons

Study of conversion coefficients

Common determination of gamma and electron intensities → determination of transition multipolarity

E0 transitions → are realized only by conversion electrons

Importance of correction on Doppler Shift (widening of line at spectrum)

Very often on beam measurement together with 4π detector systems for gammaray detection

Spectrum of conversion electrons - transition near yrast line

kinematic shift is described by Lorentz transformation:

*

*

** cos1

E

cpEE

•- coordinate system connected with moving nucleus

Compound nucleus → same velocityreaction and CE → different nucleus velocity

Determination of kinematics by nucleus detection

Study of electrons and positrons from beta decay

Measurement of Fermi-Kurie graph:

Schematic description of dependency Ne = f(Ee) in beta decay

Fermi graph for decay of tritium 3H, which is mostly used for neutrino mass determination

)E(Ekonst

EZ,F

ENeMAX

e

e

N(Ee) – number of electrons, F*(Z,Ee) – Fermi function, contains correction onCoulomb fields of nucleus and atomic electron cloud. mνc2 ≠ 0 → EMAX=Q - mνc2 Q – decay energy

Square of neutrino mass is determined

Necessity of very high resolution andMinimalization of energy loss possibilities(violation of spectrum shape)

Determination of neutrino mass

Present limit on neutrino mass (experiments at Mainz and Troick):

Experiment KATRIN

Integral electrostatic spectrometer

Determined limit for mν < 2-3 eV

Assumed sensitivity of spectrometer KATRIN

Scheme of spectrometer KATRIN

Complications: 1) Energy losses in target, molecule T2

2) Spectrometer stability

Obtained negative value of square mass

Usage of pair spectrometers for searching ofexotic particles decay

Some hypothetical particles should have decay channel to electron positron pair

Pair spectrometer APEX as example – it was not determined for axion searching

Vznikat by mohly například při srážkách těžkých iontů

Study of di-lepton pairs in high-energy physics

Sources of e+e- pairs:

Combinatorial background – its description is very important

Usage of track spectrometers

π+π- anihilation

Δ – Dalitz decay bremsstrahlung Decay of meson η

M(e+e-) [GeV/c2]

Au+Au1 GeV/n

combinato-rial background

η → e+e-

pn

10-10

10-8

10-6

0.4 0.8 1.2

φ→e+e-

ρ→ e+e-

ω→e+e-

Dilepton „cocktail“

CERES, NA50, HADES ...

Momentum resolution is very important

Spectroscopy of electron energy losses with high resolution

Set-up: 1) electron gun – electrons 2) electron spectrometer with high resolution

Electron gun EG3000 and electron spectrometer ELS5000 of LK Technologies company

Usage: 1) Surface studies by means of characteristic Auger electrons, electron scattering and diffraction 2) Structure studies

XPS method – X-ray photoelectron spectroscopy – surface, chemical analysis