ISSN 1063-7788, Physics of Atomic Nuclei, 2017, Vol. 80, No. 6, pp. 1050–1060. c  Pleiades Publishing, Ltd., 2017. NUCLEI Experiment The Study of (n, 2n) Reaction Cross Sections for Ce and Nd Isotopes up to 20 MeV ∗ M. Sahan ** , H. Sahan, and E. Tel Osmaniye Korkut Ata University, Faculty of Arts and Sciences, Department of Physics, Osmaniye, Turkey Received May 17, 2017 Abstract—Neutron cross section calculations for 136 Ce(n, 2n) 135 Ce, 138 Ce(n, 2n) 137 Ce, 140 Ce(n, 2n) 139 Ce, 142 Ce(n, 2n) 141 Ce, 142 Nd(n, 2n) 141 Nd, 144 Nd(n, 2n) 143 Nd, 146 Nd(n, 2n) 145 Nd, 148 Nd(n, 2n) 147 Nd, and 150 Nd(n, 2n) 149 Nd were done in the incident energy range from 10 to 20 MeV. The calculations were performed using three codes TALYS-1.6 for two-component Exciton model, EMPIRE-3.2 Malta for Exciton model, and ALICE/ASH for the Geometry-Dependent Hybrid (GDH) model. The results of model calculations were compared with the available experimental data and also with the evaluated data in the TENDL-2015 (based on the modified TALYS code), ENDF/B-VII.1 libraries. The calculated cross section data were compared with the available experimental data obtained from EXFOR and also compared with semiempirical formulas around 14–15 MeV. The results of model calculation were found to be in good agreement with the experimental data given in literature and semiempirical data around 14–15 MeV. DOI: 10.1134/S1063778817060199 1. INTRODUCTION The experimental crosssection data can be used for the investigation of the structural materials of the fusion reactors and for developing nuclear theoretical calculation models to explain nuclear reaction mech- anisms. Due to the experimental difficulty, the nu- clear reaction models have been developed to provide the estimation of the reaction cross sections [1–4]. Neutron activation cross-section calculations close to 14–15 MeV play an important role in developing of fusion reactor technology and in getting information of the exited states of atomic nuclei [5–7]. Most of existing information concerning the mechanism of (n, 2n), (n, p), and (n, α) reactions has been obtained from the data taken at neutron energies around 14– 15 MeV. (n, 2n) cross sections are of increasing im- portance for fast fission and fusion reactors. The the- oretical neutron crosssection calculations are hence essential for developing of the nuclear models due to the experimental difficulty [2, 3, 8, 9]. Fission products, defined as nuclei with atomic number 31–68, accumulate in an operating reactor as the fuel undergoes fission [10]. Many researchers measured the (n, 2n) cross sections in the rare-earth region according to a compilation of the (n, 2n) cross ∗ The text was submitted by the authors in English. ** E-mail: msahan2000@yahoo.com sections at 14–15 MeV. The (n, 2n) cross sections on 142,148,150 Nd were, for example, measured at 14.6-MeV detector by Kumabe et al. (1977) [11]. Since the preequilibrium process is known to be dominant in (n, 2n) reactions around 14–15 MeV in the rare-earth region, the (n, 2n) cross sec- tions of Cerium ( 136,138,140,142 Ce) and Neodymium ( 142,144,146,148,150 Nd) isotopes in the rareearth region for (n, 2n) reactions have been calculated from 10 to 20 MeV. This paper presents the theoretical calculated cross sections of Cerium ( 136,138,140,142 Ce) and Neodymium ( 142,144,146,148,150 Nd) isotopes for (n, 2n) reactions. These elements known as rare-earth element (also called rare earths or rare-earth metals) exist as minority in structural material of nuclear reactor and are formed as fission products in nuclear fuel [1, 12]. Cerium (Ce, Z = 58) is a soft, ductile, silvery-white metallic element and was discovered in 1803 and is the most abundant element of all the lanthanides. Four naturally occurring Cerium isotopes ( 136,138,140,142 Ce) are observationally stable. Cerium is the most abundant among all rare-earth metals, and finds more and more applications [13]. Neodymium (Nd, Z = 60) discovered in 1885 is a chemical element that is a member of the lanthanide (inner transition metal) series in the periodic table and is a soft silvery metal that tarnishes in air. Nat- ural Neodymium is composed of five stable isotopes 1050