Julijan Dobrinić

Nuclear excitation in by positron–electron annihilation process

Abstract In the process of nuclear excitation in positron–electron annihilation (NEPEA) experimental results for the cross-section have been found to be greater than theoretical predictions. In our previous work we applied an analysis based on our model of indistinguishable quantum oscillators to the case of NEPEA for 1078 keV in 115 In and obtained very good agreement between experiment and theory. In the present work we extend this approach to the case of 1330 keV in 111 Cd and again obtain excellent agreement between experiment and a recent theoretical prediction.

Elemental analysis of archaeological objects by X-ray emission spectroscopy

In our measurements on samples, characteristic X-rays induced by a radioactive Cd-109 source were deteced in a high resolution Si(Li) detector. In the current experimental arrangement, it is possible to detect X-rays in the interval of energy 2-20 keV. All samples have been analyzed under the same conditions. The elemental composition of two leaden seals from the Republic of Ragusa were measured. Quantitave spectrum analyses showed that in the leaden seals there is gallium and iron in addition to the lead, which is the dominant element. Concentration of bizmuth, gold and selenium were found to be within the detection limit. Metal content, with the exception of silver, have also been measured in two ancient and two medieval silver coins.

Angular correlation of double internal bremsstrahlung in the electron capture decay of 55Fe

Abstract The angular correlation of photons emitted in double internal bremsstrahlung (DIB) associated with the electron capture (EC) decay of 55 Fe has been investigated. Relative emission angles ranged from 50° to 150°. Photons from the 1 mCi source were detected in two 5 cm × 5 cm diameter NaI(Tl) counters; the sum energies of photons was in the range of 68–231 keV. Experimental results were compared with the theoretical predictions for 1s, 2s, 2p and 3p initial electron state contributions.