|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1995 : ¥800,000 (Direct Cost : ¥800,000)
High spin resonances observed in the heavy-ion scattering at energies far above the Coulomb barriers, such as ^<28>Si + ^<28>Si have been studies from viewpoints of di-nuclear molecules. We have examined the reliability of "new molecular model" by calculating partial decay widths to the elastic and inelastic channels and spin alignments.
We have obtained stable configurations to be pole-to-pole ones for prolate-prolate dinuclear systems (^<24>Mg + ^<24>Mg), and equator-to-equator ones for oblate-oblate systems (^<24>Mg + ^<24>Mg), at high spins of 30 40h. Around those equilibria, various vibrational modes have been found : "butterfly" mode keeps pole-to-pole touching and appears lower in energy, while "anti-butterfly" moves without touching and appears higher than the butterfly levels. Generally butterfly excited states show anti-alignments of spin vectors in the mutual excitation channels, and anti-butterfly states show alignments, due to the coherent vibrational motions poles keeping
in touch or not. It is possible to explain disalinments in the Strasbourg data (^<28>Si+^<28>Si fragments angular distributions). In contrast, in the ^<24>Mg + ^<24>Mg system clear disalignments have not found in the (2^+, 2^+) channel, but found in the (4^+, 2^+) channel, which seems to be in agreement with experiments.
Recent particle-partile-gamma measurements in ^<28>Si + ^<28>Si (Strasbourg group) have exhibited "m=0 in normal to the reaction plane" gamma-ray angular distributions. We have searched for the configurations with "m=0" dominance in the normal modes for ^<28>Si + ^<28>Si system, and found K-mixing (tilting mode) due to triaxial equilibrium configurations (equator-equator ones) in extremely high spins, In the reaction course, equators are parallel to the plane, which gives spin vectors parallel to the plane and shows "m=0" gamma-ray distributions.
3. ^<28>Si+^<28>Si系では、超高スピンでは慣性モーメントが最大となる軸の回りに全体が回転する事(ティルチングモードの存在)が判った。パンケーキ型変形している^<28>Si核はその端同士で接触し、平らな面が反応面に平行な形態で非軸対称な安定配位を取ると考えられる。この時、^<28>Siのスピンベクトルは反応平面上にあるので、"m=0"成分が強いと言う特徴を示し、ガンマ線角分布のデータを良く再現する。 Less