Study Of High Spin States In ^130,131Ba And Lifetime Measurement Of Low-lying States In ⁸⁷Zr

In this dissertation,the new experimental results of high spin states in ^130,131Ba and lifetime measurement of low-lying states in ⁸⁷Zr are presented and the related physics is discussed.The high-spin states in ^130,131Ba were populated via the ¹²²Sn?13C,xn?reaction at beam energy of 65 MeV.Coincidence measurements were carried out using the GALILEO array in conjunction with the ancillaries EUCLIDES and Neutron Wall.Based on the new data,the level schemes of ^130,131Ba were revised and extended significantly.The level structure built on the K^?=8^-,T_1/2=9.5 ms isomer of ¹³⁰Ba was identified for the first time,filling the gap in the systematics of the dipole bands built on the 8 isomers in the N=74 isotones from ¹²⁸Xe to ¹³⁸Gd.The extracted experimental g_K and g_R gyromagnetic factors are in agreement with those for the?7/2^?10?[404]9/2^-[514]Nilsson configuration.Particle-rotor model calculations give an understanding of the limited degree of K mixing.The experimental information on the K^?=8^-isomer of ¹³⁰Ba is the most complete among the K isomers in the N=74isotones.The first case of t-band?for which the angular momenta of the unpaired particles are aligned along a tilted axis.?in A?130 mass region was observed in ¹³⁰Ba,and four quasi-particle band,odd spin branchs of two super?S?bands?which are the extension of the ground band after the first backbend in even-even nuclei.?and three negative parity bands were built.The large signature splitting of the two S bands indicated that the bands have the oblate and prolate shapes associated with proton and neutron excitations,respectively.According to the experimental data and the structure systematics of the neighbouring nuclei,the configurations of all new observed bands were assigned.In ¹³¹Ba,nineteen bands were observed,of which nine bands are newly observed in present work.Some previously known bands were revised,and spin and parity of all observed bands were confirmed or assigned.The multiple chiral doublet?M?D?phenomenon including one pair negative-and two pairs of positive-parity chiral bands was observed in ¹³¹Ba.This extends the systemtics of chiral bands in N=75 isotones.The E1 transitions between the positive-and negative-parity chiral bands,suggesting the octupole correlation between these bands,were observed.According to the properties of the bands and the structure systematics of the neighbouring nuclei,the configurations of all observed bands were confirmed or tentatively assigned.Lifetime of the low-lying states in ⁸⁷Zr populated by the?⁺decay of ⁸⁷Nb was measured using?-?delayed coincidence technique.The B?E2;7/2₁⁺?9/2₁⁺?value in⁸⁷Zr deduced from the new lifetime is similar to the B?E2;0₁⁺?2₁⁺?value in weakly deformed ⁸⁶Zr.This manifests that the 7/2₁⁺state in ⁸⁷Zr has a similar collectivity with the 2₁⁺state in ⁸⁶Zr.The present experimental value shows a good systematics in N=47 isotones and is in agreement with the recent shell model calculations.In the framework of the shell model,the change of the B?E2?values with the proton number both in N=46 even-even isotones and N=47 odd A isotones is aqualitativly interpreted.