RESUMO
In the present work, the determinations of k0 and Q0 for 74Se, 113In, 186W and 191Ir targets were performed. The irradiations were conducted near the core of the IEA-R1 4.5â¯MW swimming-pool nuclear research reactor of the Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP - Nuclear and Energy Research Institute), in São Paulo, Brazil. The irradiation position was chosen where the neutron spectrum shape parameter α is very close to zero. For this reason, the correction to be applied for the determination of Q0 is very close to one, thus improving the accuracy of the results. For each experiment, two irradiations were carried out in sequence: the first one with bare samples and the second with a cadmium cover around the samples. All partial uncertainties were considered, applying the covariance matrix methodology. The final results were compared with the literature.
RESUMO
The values of k(0) and Q(0) for (64)Zn(n,γ)(65)Zn and (68)Zn(n,γ)(69m)Zn reactions were determined experimentally. The irradiations were performed near the core of the IEA-R1 3.5MW nuclear research reactor of the Nuclear and Energy Research Institute - IPEN-CNEN/SP, in São Paulo, Brazil. The results for the neutron field parameters f and α were 49.7(19) and -1.1(31)×10(-3), respectively. The resulting values of k(0) and Q(0) for (64)Zn(n,γ)(65)Zn reaction were 5.63(8)×10(-3) and 1.69(6), respectively, and the corresponding values for (68)Zn(n,γ)(69m)Zn reaction were 4.00(6)×10(-4) and 2.34(4), respectively. These results were compared with the literature.
RESUMO
In an intercomparison exercise, the Monte Carlo codes most commonly used in gamma-ray spectrometry today were compared with each other in order to gauge the differences between them in terms of typical applications. No reference was made to experimental data; instead, the aim was to confront the codes with each other, as they were applied to the calculation of full-energy-peak and total efficiencies. Surprising differences between the results of different codes were revealed.
RESUMO
A practical method to determine the heating and cooling curves of x-ray tube assemblies with rotating anode x-ray tube is proposed. Available procedures to obtain these curves as described in the literature are performed during operation of the equipment, and the precision of the method depends on the knowledge of the total energy applied in the system. In the present work we describe procedures which use a calorimetric system and do not require the operation of the x-ray equipment. The method was applied successfully to a x-ray tube assembly that was under test in our laboratory.
