| Budget Amount *help |
¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
The basic theoretical approach for studying the nuclear rotational motions is the cranking model, which is based on the picture of uniform rotation around one of the inertia axs of selfconsistent deformation. It is a mean-field theory in the rotating frame and has been used for the analysis of high-spin states so far. It has been recognized, however, that such a simple approximation is not appropriate in some of recent experimental findings. In this project, we have considered a extended cranking approach, by which an unified understanding of many recent experimental data can be obtained.
The first extension is for the case of low-spin states. Since the usual cranking model uses semiclassical approximation valid in the high-spin limit, the electromagnetic transition probability cannot be calculated correctly. We have found the method to treat the algebraic effect of nuclear collective motion (effect of Clebsch-Gordan coefficients) more exactly, and succeeded to give a general prescription to calculate the matrix element of observables. It is applied to the various rotational bands observed in Coulomb excitations, and is confirmed that the new approach is very useful.
The second extension is for the case of general rotational motion where the rotation axis tilts against the inertia axis of the deformed body (tilted axis cranking). First, we have checked what kind of physical effects are included in the tilted axis cranking approximation by using a simple solvable model. It is found that the the effect of tilting the angular momentum axis is essential for quantities like the electromagnetic transition rates, and the tilted axis cranking gives good approximation for such quantities. Next, we have made a general program to calculate the observables in realistic nuclei by means of the tilted axis cranking. We expect that the application give us new insights for the nuclear rotational motions.
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