Analiza gama linija emitovanih nakon zahvata termalnih neutrona u ...

Analiza gama linija emitovanih nakon zahvata termalnih neutrona u germanijumuScientific discipline:SDSubject/ Key words:SKWUCHolding data:HDNote:NAbstract:ABNuсlear physicslow fon gamma spectroscopy, the thermal neutron flux,fission neutrons, Californium source, germaniumdetector, the energy line of 139.7keVLibrary of Department of Physics, Trg DositejaObradovića 4noneIn the experiment that presented by this work,spectra were recorded on an HP germanium detector thatis in iron shield in the presence of Californium source offast neutrons 252 Cf. Above source were placed plates ofpolyvinyl chloride in various thicknesses (7, 14, 26, 45,68 and 93mm). For every thickness spectra were recordedwhen about germanium crystal was placed 1mm thicklayer of cadmium and when it was removed. Fastneutrons passing through polyvinyl chloride may result inthermalisation or absorption. Recordings were done inthis way to determine how thermalisation and absorptionof neutrons affects the gamma spectra.In recorded spectra were monitored intensities ofseveral characteristic gamma lines originating from ofdifferent mechanisms: inelastic scattering, capture ofneutrons on hydrogen and capture of neutrons ongermanium nuclei. We analyzed the intensities of gammalines at energies of 139.7keV, 198.3keV, 595.8keV,691.3keV and 2223keV.It was found that the energies of the gamma linesof 139.7keV and 198.3keV are not only induced bythermal neutron capture, but to some extent with capturefast neutrons. In practice, gamma line on energy of139.7keV is used to estimate the thermal neutron flux soit would be desirable with some new experiments toverify quantitative measure that slow neutrons influencethe creation of the gamma line energy of 139.7keV, andwith what measure fast neutrons affects on her intensity.-76-