The Measurements Of The Nuclear Data In The Reactions Induced By 14MeV Neutrons

The accurate mesurements of the nuclear data are relative to many fields of the Nuclear and Defense industries. The high accurate data will provide reliable support of theory and experimental for the designs of the industral equippments and the miniaturization of the nuclear weapons. The study of the cross sections of nuclear reactions induced by 14MeV neutrons is one of the important tasks in the Nuclear Physics fields. It can provide the evidences of the interactions between the incident particles and the nucleus in the target. It is helpful to make human beings to understand the nuclear force and the nuclear structure as well. It is the basal part to check the nuclear theory out. Furthermore, the nuclear cross section data are also the foundation of the nuclear technology and the applications of nuclear energy. Especially it plays an important role in the following fields: the establishing and improving of the nuclear reaction models, the design of the fusion reactor, the building of the nuclear data base and the nuclear astrophysics.The capture cross section is a more important parameter in the nuclear reactions induced by neutrons. It is used to make the principle of the nuclear reactions clear, to study the rules of the high excited states of the atomic nucleus; fission cross section provide more significant data of the nuclear powers and the nuclear weapons. The measurement of differential cross section could be helpful to indicate the characteristic of nuclear reactions in detail and to perform more further study of the nuclear reaction.The nuclear power will be the major energy source in our country. This situation indicates that the development of nuclear power will be more quickly. There are many nuclear data specially the cross section data are needed in the design of nuclear reactors, such as fission cross sections of the fission substances, elastic scattering cross sections of the moderating materials, absorption cross sections of the control and shielding materials.With the farther development of the design and test of the nuclear fields and the computer digital simulations, it needs the nuclear data base with the characteristic of high accuracy, wide energy boundary, more nuclides and species. More requests are submitted to measure the nuclear data for the applications of nuclear technology, focusing on fissionable nucleus, heavy nucleus, cascade reaction nucleus and some fission product nucleus.The more demand of the limited energy sources such as coal and petroleum in the world nowadays, the more work is needed to be done in developing new energy sources. The better way to solve the energy source problem is to develop and to utilize the fusion power. More cross sections induced by neutrons are needed to evaluate the radioactive wastes in the fusion reactor and to adopt proper structure and shielding materials in the fusion reactor. The cross sections induced by 14 MeV neutrons are relative to the safe operation, the dose levels of the surrounding environment, the reuse, treatment and disposal of the radioactive wastes, etc. With the development of our national defense and the work of verification and anti-verification of nuclear weapons, a number of nuclear cross sections are needed. The nuclear cross sections could be widely used in measuring the neutron flux and spectroscopy, activation analysis, producing radioisotope, nuclear medicine, irradiations, geoscience (petroleum logging, mine explorations etc.) and nuclear astrophysics.The fission product yield is also more important in the nuclear science, technology and engineering, such as the calculations in decay heat, shieldings, doses, fuel burnup, fuel processing, the treatment of radioactive wastes and nuclear security, etc. The fission product yields are applied for evaluating the level of nuclear explosion in the field of nuclear test. The fission product yields related to the energies of incident neutrons must be more accurate because there are continuum spectra neutrons with broad energy ranges generated in the nuclear explosion. Furthermore, radioactive beam is required in many foundational research,including neutron-rich beam which can be generated by bombarding the fissionable materials with high intensity proton beam and separated from the fission product by the technology of accelerating particles. Thus this needs more accurate fission product yields provided as well.The primary work were performed in seeking for likely experimental plan, the adjustments of laboratory apparatus and the design of our laboratory. The direct Y -spectroscopy method will be adopted to measure the fission product yields of U-238 induced by fast neutrons in future work. First dual fission ionization chamber is used to determine the fission rate during the U-238 sample irradiated in the accelerator's neutron field; second HpGe Y -spectroscopy is used to measure the radioactivity and to obtain the generation rate of the product nucleus; finally the cumulative yields of the product nucleus can be given. The measurement system of the cross section induced by 14 MeV neutrons and the determinations of corrective value were introduced in this paper. The cross sections of Osmium and Bromine induced by 14 MeV neutrons were presented. Our samples were irradiated at the K-400 Neutron Generator at Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics(CAEP); the neutron energies in the measurements were determined by the cross section ratios for ⁹³Nb(n, 2n)^92mNb and ⁹⁰Zr(n, 2n)^89m+gZr reactions; the neutron flux was monitored by the standard cross section of ⁹³Nb(n, 2n)^92mNb reaction; the y radioactivities were measured with GEM-60P coaxial high-purity germanium (HPGe) detector (ORTEC, made in USA).