Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Harada, Hideo
Applied Sciences (Internet), 11(14), p.6558_1 - 6558_20, 2021/07
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)For accuracy improvement of neutron activation analysis and neutron capture cross section, bias effects are investigated on g- and s-factors in the Westcott convention. As origins of biases, a joining function shape, neutron temperature and sample temperature, have been investigated. Biases are quantitatively deduced for two 1/v isotopes (
Au, 
Co) and six non-1/v isotopes (
Am, 
Eu, 
Rh, 
In, 
Hf, 
Ra). The s-factor calculated with a joining function deduced recently by a detailed Monte Carlo simulation is compared to s-factors calculated with traditional joining functions by Westcott. The results show the bias induced by sample temperature is small as the order of 0.1% for g-factor and the order of 1% for s-factor. On the other hand, biases induced by a joining function shape for s-factor depend significantly on both isotopes and neutron temperature. As the result, reaction rates are also affected significantly as well. The bias size on reaction rate is given in the case of epithermal neutron index r = 0.1, for the eight isotopes.
Harada, Hideo; Takayama, Naoki; Komeda, Masao
Journal of Physics Communications (Internet), 4(8), p.085004_1 - 085004_17, 2020/08
A new convention of epithermal neutron spectrum is formulated for improving accuracy of resonance integrals. The new type function is proposed as an approximating function of epithermal neutron spectrum based on calculations by the state-of-art Monte Carlo code MVP-3. Bias effects on determination of resonance integrals due to utilizing approximating functions of the traditional types and the new type are compared. The other bias effect is also investigated, which is caused by neglecting position dependence of a neutron spectrum inside an irradiation capsule. For demonstrating the bias effects due to these assumptions on neutron spectrum quantitatively in a practical case, the thermal neutron-capture cross section and resonance integral of 
Cs measured at a research reactor JRR-3 are re-evaluated. A superior property of the proposed new convention is discussed. The experimental method is proposed to determine the new shape factor 
introduced in the convention by a combinational use of triple flux monitors (Au, Co and 
Zr), and its analytical methodology is formulated.
