转动诱发原子核量子相变的一种可能途径

A possible route of nuclear quantum phase transition induced by rotation

基于微观IBM理论,提出转动诱导出玻色子量子相变的一种可能途径:一旦原子核在受到高能激发或作快速旋转时,假如外界提供的能量足以使玻色子完成拆对顺排,则核处于集体相与单粒子态的共存相,其特征是出现较密集的能谱;假如能量不足以完成拆对或顺排,可能发生两种情况之一,当核旋转达到某个临界转动频率ωc时,或者一个高角动量的玻色子脱离“集体”而“游离”出来,或者发生一个高角动量的玻色子转变为一个低角动量的玻色子,核仍旧处于集体相;均会伴随出现光辐射,产生基态带的一条能级———相变信号.正是这类玻色子相变导致了原子核的量子相变.本物理图像统一了玻色子拆对顺排相变和退耦释放光子相变的描述.以100Pd核的141+,142+和143+态的产生机理为例,对模型作了仔细说明.

Based on the microscopic IBM-theory, a possible route of boson quantum phase transition induced by rotation is put forward. Once the nucleus is in a high-energy excited or high-speed rotating state, the nucleus would occupy the coexist-phase of collective superfluid phase with single-particle phase, if the energy is enough to realize the boson＇ s breaking up and aligning in the nucleus, characterized by a more dense spectrum. If the energy is not enough, either of following two cases will happen. When the rotating state of nucleus arrives at critical rotating-frequency coc, one case is that a higher-momentum boson may be decoupled from the ‘collective state＇ as a quantum ‘free beson＇, the other case is that the transition from a higher-momentum beson to a lower-momentum beson takes place, and the nucleus remaius in a collective state. Both cases are acompanied by the light-emission from the transition from higher excited-state to lower excited-state, and the total superfluous band energy of nuclear system is released by means of excited element, and an energy level appears in the ground-state band, which signifies a quantum phase transition. Just owing to these beson quantum phase transition, nuclear quantum phase transition could happen. Descriptions of beson phase transitions on breaking up and aligning as well as on decoupled and released photons have been united in this physical picture. As an example, this model has been expounded with the mechanism of producing 141^＋ , 142^＋ , and 143^＋ states on the 100^Pd nucleus.