Comparison of partial photoneutron reaction cross sections reliability for 140,142Ce

Varlamov, V.V.; Barbaryan, V.A.; Peskov, N.N.

Авторы: Varlamov V.V., Barbaryan V.A., Peskov N.N.
Сборник: Международная конференция «Ядро-2017» (67-е Совещание по ядерной спектроскопии и структуре атомного ядра), 12-15 сентября 2017 г., Алматы, Республика Казахстан. Тезисы
Тезисы
Год издания: 2017
Место издания: РГП «Институт ядерной физики» Алматы, Республика Казахстан
Первая страница: 26
Последняя страница: 27
Аннотация: Using experimental–theoretical method for partial photoneutron reaction cross sections evaluation new data satisfied to data reliability criteria were obtained for many nuclei (for example, 91,94Zr, 115In, 112–124Sn, 133Cs, 159Tb, 181Ta, 186-192Os, 197Au, 208Pb, 209Bi). The only experimental reaction cross section SIGMAexp(g, xn) free from the problems of experimental determination of neutron multiplicity was used and shared into the partial parts using the equations Ftheori = SIGMAtheor(g, 1n)/SIGMAtheor(g ,xn) of the combined model of photonuclear reactions. It was shown that evaluated cross sections differ noticeably from experimental once and that the main of that reasons are the complicated dependence of neutron multiplicity on its measured kinetic energy. The isotopes 140,142Ce are of special interest concern the problems of data reliability because there are the significant difference between experimental data obtained for partial photoneutron reactions (g, 1n) and (g, 2n) in using quasimonoenergetic annihilation photon beam and neutron multiplicity sorting method. The point is that for 140Ce integrated cross section of the (g, 1n) reaction is 1941 MeV mb and that of (g, 2n) reaction is 457 MeV mb. At the same time for 142Ce correspondent values are 1022 and 1186 MeV mb. Therefore there are noticeable differences between the integrated cross sections for total photoneutron reaction (g, Sn) = [(g, 1n) + (g, 2n)] – 2400 and 2210 MeV mb correspondingly and neutron yield reaction (g, xn) = [(g, 1n) +2 (g, 2n)] – 2857 and 3396 MeV mb. The possible reason is the large differences between energy thresholds Bn1 and Bn2 of (g, 1n) and (g, 2n) on 140,142Ce isotopes. Bn1 are correspondingly 9.2 and 7.16 MeV but Bn2 are 16.66 and 12.59 MeV. Experimental data the reactions (g, 1n) and (g, 2n) on both isotopes were analyzed using data reliability criteria. It was found out that with the exception of narrow energy range (~ 19-21 MeV) in 142Ce there are no noticeable disagreements with criteria used. At the same time the energy dependencies of Fexpi differ noticeably from those of Ftheori. Therefore for both isotopes evaluated partial reaction cross sections were obtained using the experimental-theoretical method. The way of new cross sections evaluation was the following – SIGMAeval(g, in) = Ftheori • SIGMAexp(g, xn). It means that competition between partial reactions is in accordance with model and their sum SIGMAeval(g, xn) is equal to SIGMAexp(g, xn) also free from problems mentioned. Using evaluated partial reactions cross sections new data were obtained also for total photoneutron reaction [(g, 1n) + (g, 2n) + (g, 3n) + …] ~ SIGMA(g, abs).
Добавил в систему: Варламов Владимир Васильевич

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