Experimental Study Of High-spin States In Odd-odd ¹⁵⁶Tm Nucleus

The study of high spin states of nuclei has developed into a new stage with more and more experimental results being obtained to facilitate the progress of nuclear theories. As an object by which the interaction between valence quasi-proton and quasi-neutron can be investigated, the studies of odd-odd nuclei have been paid close attention. The study of high spin states now faces many problems, for example the excitation energy of levels, the configurations of rotational bands, the spin and parity of bandheads in odd-odd nuclei are determined tentatively in many cases. All these may mislead the study of theoretical research. Furthermore, the lack of experimental data in many cases makes it impossible to check the theoretical interpretations. This thesis, following the above ideas, describes the details of odd-odd 156Tm high spin study.The first part is introduction. Such as a brief review of the development of nuclear physics history and several commonly used methods method about how to layout nucleus high spin states, such as heavy particle fusion evaporation reaction, heavy particle multiple Coulomb excitation, heavy particle induced fission promptγ-spectroscopy etc., and they gave an explanation of the advantages and disadvantages of the method. Because of the experimental conditions, Early research work in the high-spin state have used the radioactive decay process, as well as heavy nucleus neutron capture process methods program the nucleus high spin states, The results has provided a powerful experimental evidence for the early collective rotational spectrum of nucleus. The advantages of these methods is that a clean objective and very good selectivity has provided, however, its shortcomings is that it cannot program a higher spin states. It also provides a method called systematic method that often used on analyzing the structure of nucleus. Frankly speaking, Systematic Analysis Method is only a study of experience, and not strictly theoretical foundation cannot be completely ruled out a singular nuclear incident (such as the shell effect or association), which also must be approved by the inference and experimental test, but Systematic Analysis Method as the reasonableness of the method and effectiveness has been fully affirmed and confirmed.The second part is a detailed in-beam gamma spectroscopy. The high-spin states of 156Tm were populated through the reaction 144Sm(19F,2p5n)156Tm, at four beam energy, Elab1=110MeV,Elab2=108MeV,Elab3=106MeV,Elab4=106MeV provided by the HI-13 tandem accelerator of CIAE in Beijing. The target was consisted of self-supporting one stacked foil of 144Sm, thickness 1.2mg/cm2. Theγ-rays emitted from the residuals were detected in promptγ-γcoincidence measurement with a combined detector array. Fourteen BGO Compton's suppressed HPGe detectors were used in this experiment. The detectors were placed at angles of 90°, 38°, 142°, 60°, 149°, 34°and 24.76°to the beam direction. A total of about 2.45×107 coincidence events were accumulated. The experimental data will be recorded and used as chronological record to the computer.The third part is about the offline data processing. We inverse the data acquired from the data acquiring system, it can be used for the analysis of the symmetry of the Eγ-Eγmatrix and DCO for the analysis of the non-symmetric Eγ-Eγmatrix. Symmetric matrix to the X or Y axis on a projection of the total projection spectrum, by fenestration and analysis we are concerned with the relationship between theγ-ray spectroscopy. Before the analysis, we need for the energy calibration and efficiency calibration of various detector and the detection arrays. Energy calibration is acquired by through the selection of the energy generated in the known characteristic peak. The efficiency calibration are standard by the standard peak of 152Eu.Then we could get the relatively array detection efficiency calibration curve, as a future-ray intensity of the amendment.γ-ray intensity through the peak for the area and the corresponding detection efficiency to determine the peak area for the three main methods. Through a single spectrum for the other a total projection of the spectrum, spectrum-as accurate, but it is simple. The third window for the spectrum, fenestration larger spectral method of error, usually powerless when the former two methods used. In this work, we have adopted a spectral method is fenestration. With the experimental data fitting procedure fitting the peak area of peak area, it is necessary to pay special attention to the background of continuity. After deducting the end, it is necessary to a wide selection of the correct identification to prevent because a lot of energy near-ray single-spectrum brought in the very high, leading to the peak area fitting grave error. Then try to fit the scope of the election wider, as far as possible, includes all the nearby peaks at the peak at the same time fitting, in order to reduce the introduction of errors.The forth part is divided into experimental results and analysis. Based on the work of Sun huibin and Li mingfei et al., we extended the level structure of 156Tm. A more completely band structure were established. Most of the relative intensity of theγ-rays of 156Tm was measured. The Band B and the Band D are built for the first time, which help the assignment of the configuration of band A. The band A was assigned to theπh11/2?νi13/2(α=1) configuration,the band B was assigned to theπh11/2?νi13/2(α=0) configuration. Through Systematic Analysis Method, we analyzing the level scheme of 156Tm and 154Ho, 156Tm and 158Tm, the configuration are systematic assigned.