Theoretical Calculation for Photonuclear Reaction of 142-146,148,150Nd
JIN Yongli, TIAN Yuan, TAO Xi, WANG Jimin, XU Ruirui, LIU Ping, GE Zhigang
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Photonuclear reaction data can describe the physical process of the interaction between photons and nuclei as well as the emission of particles. It has important applications in nuclear reactor physics, accelerators, radiation shielding, activation analysis, nuclear waste transmutation, and nuclear synthesis of celestial bodies. The natural stable isotopes of neodymium (Nd), 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, 148Nd and 150Nd, are important fission products which are necessary in the activation analysis and reactor physics. In order to provide more complete and better quality data to the nuclear application, the Chinese theoretical photonuclear reaction program MENDG is developed by China Nuclear Data Center and Nankai University, which contains the optical model, HauserFeshbach model and Exciton models, and can deal with the complicated particle emission reactions below the photon induced energy 200 MeV. Base on MENDG, the nuclear data of photon nuclear reactions of 142146,148,150Nd in the energy range below 200 MeV were systematically calculated in this work. It should be noticed before the theoretical calculations that, various existing experimental data in EXFOR for photonuclear reaction including (γ, xn), (γ, sn), (γ, in) (i=1,4) and so on were collected and evaluated, some discrepancies and selfinconsistencies among different data were removed, and the present theoretical calculations were guided under the well evaluated measurements. Photon absorption cross sections for the photon incident energy below 200 MeV were firstly determined with the classical photon strength functions and the quasideuteron model. Eight formula with Lorentz functions including the standard Lorentzian (SLO) model, the enhanced generalized Lorentzian (EGLO) model, the Hybrid (GH) model, the generalized Fermiliquid (GFL) model, and the three kinds of modified Lorentzian (MLO1, MLO2, MLO3) models were all utilized to describe the giant dipole resonance below about 40 MeV, and SLO model was validated as the suitable one in this case with the minimum Chi square for experimental data and calculations. Then, the theoretical calculations of photonuclear reaction of 142146,148,150Nd were carried out by MENDG. The competing reactions especially for the multiple neutron emissions were globally obtained by the six optimized GilbertCameron level density parameters, the theoretical selfconsistency for 142146,148,150Nd were satisfied as much as possible. The partial photoneutron cross sections were specially discussed systematically, and satisfying theoretical descriptions were observed in the global case. Moreover, to improve the theoretical results, the local parameters were also adjusted for each isotope and better fitness with the experimental data can be observed comparing to the global ones. As a result, all the theoretical data are good in physics and are included in the photonuclear data sublibrary of CENDL32.