Study Of ? Angular Correlation After ⁶Li+⁸⁹Y Fusion Reaction And The Decay Scheme Of Residual Nuclei ⁹²Mo

The domestic research group has completed a fusion reaction of ⁶Li+⁸⁹Y,obtained the ?-ray energy spectrum after the reaction,and carried out a series of studies on the fusion reaction.Based on the ?-ray spectrum data obtained from this experiment,two aspects of the work about angular correlation study and reconstruction of the residual nuclear decay scheme are carried out.Decay scheme is an important tool for studying nuclear structure.Only through the continuous experiments and establishment of new scheme can new breakthroughs be made in the field of nuclear structure and radionuclide application.In this paper,5 sets of standard sources are used to calibrate the efficiency of GALILEO detector,the fitting efficiency of the whole and each group of detectors is obtained,and the data of source ¹³³Ba which may have problems are processed.The final fitting coefficients are mostly above 0.97 and the fitting degree is very good.From the energy spectrum measured by the detector after the efficiency calibration,it can be found that the scattering direction is perpendicular to the beam direction,so the residual nuclear is polarized,and the probability of the residual nuclear emitting?-rays in each direction is also different.Through calculating the relative error of?-ray energy at different angles and the detection efficiency of?-ray energy in standard source,it is found that the relative error of standard source is small and can be ignored,but the residual nuclear has obvious error in all directions.It can be seen that the polarization of the residual nuclear leads to angular correlation in?-ray emission.The ?-rays with different spin difference were selected in energy spectrum,and their relative intensity changed at different detector angles.When?I=2,the intensity of the ?-ray increases with the angle increasing;when?I=1,it decreases.This is because there is an electromagnetic field around the detector,whose interaction with the dipole and electric quadrupole of the nucleus causes the intermediate state in the cascade transition to change the direction of the spin,namely disturbance angle correlation,which also explains the formula R_ADO>1 or R_ADO<1 related to the ?-ray angle correlation of the oriented nucleus when?I=2 or?I=1.Another 2 sets of?-rays with different energy were selected to test the intensity ratio at different angles and operating times.It was found that the intensity ratio almost didn't change over time,indicating that the efficiency stability of GALILEO detector array is good,which also means that the efficiency calibration we made before is accurate and effective.The ?-rays with cascade relationship were found by windowing the ?energy spectrum,and remain ⁹²Mo and other ⁹¹Mo?⁹²Nb?⁹¹Nb?⁹¹Zr?⁹⁰Zr?⁹⁰Y and ⁸⁹Y in the reaction were determined by combining the query data in NNDC.Referring to the similar experiments⁷⁴Ge(²⁸Si,2?2n?)and ⁹⁰Zr(?,2n?),the new energy levels and transitions in the ⁶Li+⁸⁹Y reaction were found according to the cascade relationship between?-rays,and the decay scheme of ⁹²Mo was reconstructed.Compared with the previous versions,it can be found that the newly added energy levels are mainly in the highly excited state.It because the highly excited energy level field produced by the neutrons on the g_9/2energy level crossed the neutron magic number shell cannot obtained precise level and cascade relationships by theoretical calculation,so continuous experiments are needed to improve them.This work is also helpful to the study of nuclear structure.