Место издания:Saint-Petersburg University Saint-Petersburg
Первая страница:65
Последняя страница:65
Аннотация:In the frame of program of analysis and evaluation of total and partial photoneutron reaction cross sections the investigation of significant systematical disagreements between the results of various experiments were continued.
New clear simple objective and absolute criteria of data reliability and authenticity - transitional photoneutron multiplicity functions Fi = SIG(g,in)/SIG(g,xn) = SIG(g,in)/[SIG(g,n) + 2SIG(g,2n) + 3SIG(g,3n) + …], which have values not higher than 1.00, 0.50, 0.33,…., correspondingly were introduced. Additionally functions fi = SIG(g,in)/SIG(g,sn) = SIG(g,in)/[SIG-exp(gn) + SIG-exp(g,2n) + SIG-exp(g,3n) + …] were used (fi < 1.0). That was shown that many experimental data obtained using various experimental methods of photoneutron multiplicity sorting are not reliable and authentic (for example, F2 > 0.5). The main manifestation of that is appearing of non-physical negative value regions in SIG(g,n) reaction cross sections.
The new experimentally-theoretical treatment was proposed for partial reaction cross section data evaluation in which only experimental data for total neutron yield reaction cross section SIG-exp(g,xn), free from the neutron multiplicity sorting problems, is used for partial reaction cross section evaluation together with functions Fi-theor, calculated in the frame of modern model for photonuclear reactions. Evaluations of reliable and authentic data on cross sections for partial reactions (g,n), (g,2n) and (g,3n) - SIG-eval(g,in) = Fi-theor • SIG-exp(x,xn) - were carried out for 90Zr, 115In, 181Ta, 208Pb in addition to those for 112,114,116,117,118,119,120,122,124Sn [1, 2], 159Tb [1] and 197Au. New evaluated data are in agreement with the results of modern induced activity experiments free from neutron multiplicity sorting problems.
Deviations of evaluated data from experimental ones are large, so the situation found out creates a lot of serious physical problems – many very important things for various applications must be reanalyzed.