RESUMO
Photo-absorption of γ-rays in thin Al, Co, Ti, and Mo convertors was examined with the aim to produce quasi monoenergetic photoelectrons having an energy spread of 0.5-4.7eV about mean kinetic energies at discrete values between 18632 and 80321eV. The photoelectron rates were estimated for commercial photon sources of (241)Am, (119m)Sn, (125m)Te and (109)Cd with activities of 0.55-3.7GBq. Photoelectrons ejected by (241)Am γ- and X-rays from Co convertors were measured with two different electron spectrometers and obtained energy spectra were compared with Monte Carlo predictions.
RESUMO
The mono-energetic conversion electrons from the decay of (83m)Kr represent a unique tool for energy calibration and systematic studies of the tritium beta spectrum measured in neutrino mass determination experiments. For this reason, the corresponding parent isotope was produced in reactions (nat)Kr(p,xn)(83)Rb. The behaviour of (83)Rb (T(1/2)=86.2d) and its daughter product (83m)Kr (T(1/2)=1.83h) was examined, when the (83)Rb was trapped in a cation-exchanger chromatographic paper or in zeolite. Using gamma spectroscopy measurements, recommendations for the production of a (83)Rb/(83m)Kr radionuclide generator based on these cation-exchangers and suitable for the neutrino mass determination experiment KATRIN were deduced.
RESUMO
A general statistical test of the stability of measurement conditions was demonstrated on the beta-spectra of 241Pu cumulated during four years. The alpha- and gamma-ray spectroscopy indicated stability of the 241Pu source. Monte Carlo modelling of individual collision events clarified the role of electron scattering and energy losses within a radioactive source down to energies of several hundreds of eV. The impact ionization by beta-particles of carbon and oxygen atoms in a surface contamination layer on the 241Pu and 63Ni sources was observed.
