| The symmetry of atomic nuclei has always been an important field of nuclear physics research.Chiral symmetry as a basic symmetry widely exists in nature.S.Frauendorf and Jie Meng predicted chiral symmetry in atomic nuclei in 1997.In experimental,a pair of nearly degenerate ΔI=1 bands with the same parity,similar energy and transition properties,called chiral doublet bands,can be observed.So far,the chirality of atomic nuclei has become a hot topic in nuclear research,and more than 50 experimental candidates have been reported in A≈80,100,130,and 190 mass regions.Despite being a nucleus with early observation of nearly degenerate doublet structure,132La has been found in recent studies to have significantly different B(E2)values for the doublet bands,and has not formed chiral band structure.Therefore,it is of great significance to carry out studies on the high-spin states of 132La.The study of octupole deformation in atomic nuclei that reflection symmetry is broken has important significance.In the region of particle numbers near 34(g9/2?p3/2),56(h11/2 ?d5/2),88(i13/2?f7/2)and 134(j13/2?g9/2),strong octupole correlations occurs when two opposite parity orbits with angular momentum differ by 3h.For atomic nuclei with stable octupole deformation,the value of energy displacement between positive and negative parity bands should be close to 0,the rotational frequency ratio should be close to 1,and A large B(E1)/B(E2)branching ratio.The proton number of 132La is very close to the theoretical prediction of octupole magic number 56,and there are multiple E1 transitions between positive and negative parity bands,which indicates the possibility of octupole correlations.The experiment was performed in the Argonne National Laboratory,United States.Excited states in 132La were populated using the 123Sb(16O,2p5n)reaction at a beam energy of 80 MeV.In the experiment about 3.57 × 109 threeand higher-fold events were measured.Based on the analysis of data,high-spin states in 132La have been studied.According to experimental information,the B(E1)/B(E2)branching ratio,the energy displacement and the rotational frequency ratio between positive and negative parity bands were obtained for 132La and compared with experimental data of nearby odd-odd Uuclei 124Cs and isotopes 146La.There is a possibility of octupole correlations in 132La.This present Letter systematically compared nuclei with octupole correlations near 132La with octupole correlations,which is consistent with theoretical predictions that nuclei with nucleon numbers around 56 or 88 have octupole correlations.In addition,the B(E1)values shows that the value of B(E1)values for nuclei with mass number A～150(proton number near 56 and neutron number near 88)is significantly higher than that for nuclei with mass number A～130(only proton number near 56 and neutron number far from 88),which further verifies the existence of octupole magic numbers.In addition,based on the spectroscopic analysis,machine learning,directed graphs,adjacency matrices and the idea of neural networks and multilayer perceptrons.A program for automatically experimental data processing was written by simulating the actual data processing.The current results are not good,but it provides an idea for this work. |
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