Lifetime measurements of excited states in 163W

缺中子W同位素的核结构演化表明，过渡核163W （N=89）在W同位素链中占据了一个有趣的位置。中子亏缺W同位素的中子费米表面位于f7/2、h9/2和i13/2亚壳层轨道附近。先前的研究表明，164W的第一个后弯是由于一对i13/2中子的旋转对准，而在162W，一对h9/2中子被发现是第一个后弯的原因。这意味着涉及h9/2和i13/2轨道的构型应该在163W处于相似的激发能，因此竞争形成yrast态。先前的实验已经在163W建立了激发态，包括建立在vi13/2轨道上的激发态和建立在vh9/2和vf7/2构型上的能带。为了测量163W激发态的平均寿命，使用DPUNS柱塞装置与RITU充气分离器以及JUROGAM II和GREAT光谱仪一起进行了反冲标记y-y符合rds测量。将从数据中提取出yrast波段低洼状态的寿命和核变形，并结合邻近同位素的测量进行分析。

The evolution of nuclear structure in the neutron-deficient W isotopes has revealed that the transitional nucleus 163W (N=89) occupies an intriguing position in the chain of W isotopes. The neutron Fermi surface in the neutron-deficient W isotopes lies close to f7/2, h9/2 and i13/2 subshell orbitals. Previous studies have indicated that the first backbend in 164W is due to the rotational alignment of a pair of i13/2 neutrons, whereas in 162W a pair of h9/2 neutrons were found to be the cause of the first backbend. This implies that configurations involving h9/2 and i13/2 orbitals should be at similar excitation energies in 163W and hence compete to form the yrast states.Previous experiments have already established excited states in 163W, including yrast states built on the vi13/2 orbital and bands built on the vh9/2 and vf7/2 configurations. In order to measure the mean lifetimes of excited states in 163W, recoil-tagged y-y coincidence RDDS measurements have been performed using the DPUNS plunger device in conjunction with the RITU gas-filled separator and the JUROGAM II and GREAT spectrometers. Lifetimes and nuclear deformations of low lying states in the yrast band will be extracted from the data and analysed in the context of measurements of the neighbouring isotopes.