Cross Section Measurement Of⁶Li+⁹⁶Zr Fusion Reaction And Study On²⁰³po Level Structure.

In my present work,on the one hand,The high spin state of ²⁰³Po has used the heavy ion fusion evaporation reaction ¹⁹⁷Au(¹¹B,5n)²⁰³Po,and on the other hand,we studied the cross section measurement of ⁷Li+⁹⁶Zr fusion reaction.For the A²00 nuclear region,the nucleus number close to the magic number?Z=82,N=126?is mostly show a nearly spherical nucleus,which is mainly dominated by single-particle excitation and is convenient to calculate using the theoretical Shell-model.It is meaningful to study the odd-A core ²⁰³Po with Z=84 proton number close to the magic number.B.Fant et al.have given enough Level-Scheme information of²⁰³Po.From the comparison between ²⁰³Po and nucleus ²⁰⁵Po,²⁰⁷Po and ²⁰⁹Po,²⁰³Po low-excited negative parity level is not found,systematics comparison with the same neutron Pb nuclear there is also show this fact.So it is suspected that there may be a negative parity state that has not been found in the ²⁰³Po.In response to this phenomenon,I have done the following main tasks:?.This work uses the in-beam gamma spectroscopy method,and the ¹¹B beam provided by the HI-13 Tandem Accelerator of the China Institute of Atomic Energy was used to produce ²⁰³Po high-spin state,and a new ²⁰³Po level scheme was rebuilt.In the figure,a total of 9 new?transitions and 10 new levels were found,including 4 new negative parity levels.The configuration of the excited state of ²⁰³Po were determined to be:(?²_9/2)₅)?1)^-1_52??69?(9(?²_9/2)₅)?3_2?^-1 with j=0,2,4,6.The highest spin value is35/2 and the highest excitation energy is about 4.6 MeV.?.By establishing the DCO asymmetric matrix,the intensity and DCO ratio of all transitions in the scheme are recalculated,the type of newly found transition is determined,and the low excitation energy negative is given by the systematic comparison of ²⁰³Po and nucleus ²⁰⁵Po,²⁰⁷Po.The parity and configuration suggested values of the belt.?.In addition,using the K-shell spherical hybrid configuration shell model developed by the University of Tokyo,using the khhe and hkpe proton neutron interaction potentials in the Oxbash package,all the levels in 203Po are given by calculation.The calculated value of the yrast state is in good agreement with the experimental value.As the excitation energy is higher,the difference between the experimental value and the theoretical value is more obvious.The heavy ion fusion evaporation reaction of weakly bound nuclei has always been the central topic of nuclear reaction research.For some light-weight weakly bound nuclei,Break-up occurs during acceleration or reaction with the target nucleus.When a weakly bound nucleus break-up,two or more fragments may be formed.The fragments after break-up still have a certain angular momentum,then react with the target nucleus.It also can be seen from the previous experiments that the weakly bound nuclear react with the heavy target nucleus shows that the break-up effect occurs in the energy region above the Coulomb barrier,which will inhibit the total fusion reaction cross section,and the average inhibition coefficient is about 40%.In addition,from the recent cross-section measurement of ⁶Li+⁹⁶Zr system fusion reaction experiment,the total reaction cross-section inhibition effect is about 25%,which is obviously lower than the reaction cross-section of ⁶Li with heavy target inhibition coefficient of 40%.In order to identify the influence of the weakly bound nucleus on the cross-section inhibition coefficient of the medium-mass target nucleus region,we measured the fusion reaction cross section of the ⁷Li+⁹⁶Zr system and found out whether the fusion cross-section suppression effect exists in the bound nucleus and the medium-mass target region.The experiment was carried out at the China National Institute of Atomic Energy in-beam gamma terminal.A total of 14,16,18,22,24,26,28,30 MeV,8 energy points were irradiated for 100 hours.The experimental data was recorded by the logic of n=1 set by the electronics,and the peak area fitting was performed at the characteristic peaks at each energy point spectrum.The beam intensity is recorded once per second by the specified beam integrator.The dead time calculation in this experiment is close to 0,so the dead time can be neglected.