Study On The Excited States In ⁷⁸ As And The Establishment Of The Nuclear High Spin States Chart

This thesis contain of two parts:the study of the excited states of 78As,establishment and discussion about the chart of nuclear high spin states.1.The study on excited states of 78AsThe in-beam Gamma spectroscopic data of the fusion evaporation reaction of 7Li bombarding 76Ge target with a beam energy of 35 MeV are analyzed.This work has established a new level scheme of 78As,in which 30 new transitions and 16 new levels have been found,and the highest spin state has been extend-ed to 12.The spin and parity of most energy levels are specified by using the DCO and the systematic investigation of the adjacent nuclear energy spectrum structure.The newly established level scheme includes four rotational bands,three of which are newly established.Based on the analyse experimental ener-gy spectrum E(I),level splitting parameter S(I)and the reduced probability of electromagnetic transition B(M1)/B(E2)and the comparison with the neighbor-ing As isotopic,the two positive parity doubled bands are suggested as a pair of chiral doubled bands with ?g9/2(?)vg9/2 configuration,the negative parity band is specified as ?p3/2(?)vg9/2 configuration.In addition,this work also observed three electric dipole transitions E1 between the positive and negative parity bands,which indicates that octupole correlations may exist in 78As.To further verify this conjecture of the octupole correlations,we extracted the B(E1)/B(E2)and energy splitting ?E of the positive and negative parity bands to compared with those of 224Th and 78Br.It is ultimately recommended that octupole correlations exist in 78As.In conclusion,our study indicates that the odd-odd 78As nucleus has the coexistence of chiral and octupole correlation.2.Establishment and discussion about the chart of nuclear high spin statesWe systematically collected energy level diagrams of 2667 nuclides from H(Z=1)to Ds(Z=110),and recorded the number of rotational bands and gam-ma transitions of the highest spin values observed in these nuclides,as well as the detection array and coincidence count of nuclear reactions used in the ex-periments.Based on traditional nuclides chart,experimental highest spin value is a third axis,mapped the nucleus high spin nuclide chart based on this,the distribution of the number of rotational bands in the nucleus is also given.The distribution of the reaction type used to generate the highest spin state of this nuclide is also given.From the nuclides high spin chart,we can intuitively see where areas of nuclides spin highest value in the trough,has yet to be further supplemented experiments data,it provides a candidate target for the nuclear high spin state experimental study.The distribution diagram of the number of nuclear rotational bands can directly reflect the extent of nuclear deformation to a certain extent,which is basically consistent with the distribution diagram of nuclear deformation theory calculated.The main difference exists in the heavy nuclear region,which needs further experimental and theoretical research.We expect that the distribution of experimental reaction types and other experimen-tal information can help for further experimental exploration and related nuclear reaction research.