ANALYSES FOR MOLECULAR STRUCTURES IN HEAVY-ION RESONANCES BY USING PARTICLE-PARTICLE-GAMMA CORRELATIONS

分析了^ Si + ^ Si分子共振的粒子-粒子-γ数据<28><28>。利用高自旋分子模型中的R矩阵散射振幅，我们可以从理论上计算出共振衰变产生的碎片^ Si的γ射线强度<28>。实验数据表明，“rn = 0”，这意味着^ Si的自旋矢量<28>在反应平面上。我们研究了什么样的分子简正模具有这种特殊的核结构.获得这种自旋平行于平面的机制是：1.^<28>Si + ^<28>Si的稳定组态是赤道-赤道接触组态，2.这种稳定组态具有三轴形变，3.由于极高的自旋，转动（J=38），整个变形的物体绕着最高惯性矩的轴旋转，这产生了K混合，即所谓的摆动模式。那么两个^ Si的对称轴<28>垂直于平面，自旋矢量在平面上，因为它们垂直于轴。这样的旋转模式是可能的分子基态和蝴蝶和反蝴蝶模式。我们还有另一种模式扭曲，通过更简单的机制获得非对准，其中两个^<28>Si以相反的自旋矢量方向围绕分子轴自旋。通过理论计算和实验数据的比较，我们认为具有摆动转动的分子基态是共振结构的候选者。另外两个不是很好的候选人，原因如下。在蝴蝶模式和扭转模式下，自旋矢量分别平行于碎片方向和光束方向。即使自旋平行于反应平面，我们也没有从太多的集中矢量获得“m = 0”，因为“m = 0”需要“围绕z轴对称”。

Particle-particle-gamma data from ^<28>Si + ^<28>Si molecular resonances was analised. By using R-matrix scattering amplitudes from high-spin molecular model, we can theoretically calculate gamma-ray intensities from the fragments ^<28>Si which are emitted from the resonance decays. The experimental data suggest "rn = 0" which, means the spins vectors of ^<28>Si are on the reaction plane. We studied what molecular normal modes exibits such a special nuclear structure.Following mechanism has been expected to obtain the spins parallel to the plane; 1.the stable configuration of ^<28>Si + ^<28>Si is expected to be an equator-equator touching configuration, 2.such a stable configuration has a tri-axial deformation, 3.due to extremely high spin, rotation(J=38), the total deformed object rotates around the axis of highest moments of inertia, which give rise to K-mixing so called wobbling mode. Then the symmetry axes of two ^<28>Si are perpendicular to the plane, and the spin vectors are on the plane because they are orthogonal to the axes. Such a rotational mode is possible for the molecular ground state and the butterfly and anti-butterfly modes. We have also another mode twisting to obtain non-alignments by simpler mechanism, in which two ^<28>Si spin around the molecular axis in the opposite spin-vector directions. The vectors are parallel to the molecular axis which rotates on the reaction plane.Comparing theoretical results with the data, we conclude that the molecular ground state with wobbling rotation is a candidate for the resonance structure. The other two are not good candidates by the following reason. In the butterfly mode and the twisting one the spin vectors are parallel to the fragment direction and the beam one, respectively. Even with the spins parallel to the reaction plane, we obtained no "m = 0" from too much concentrated vectors to own directions, because "m = 0" require "symmetry around z-axis".