Measurement of polarization tensors in the heavy-ion induced reactions and its application to the study of the reactions of astrophysical interest

本研究旨在发展一种新的实验方法，通过测量重离子诱导转移反应产生的原子核的偏振张量来确定感兴趣的核态的自旋。利用二维位置敏感的硅半导体探测器，通过观察由于粒子或γ射线发射的反冲而产生的反应产物的角度展宽和能量展宽，计划以高效率测量偏振张量。研究了一维硅探测器对α粒子的能量和位置响应，以及动能从几MeV到几十MeV的动能范围从几MeV到几十MeV的粒子。通过对能量和位置信号应用门控积分器，获得了与被测位置良好的线性关系。能源弹道赤字也被发现可以忽略不计。二维位置灵敏探测器的响应研究正在进行中，最重要的是要建立可靠的测定核自旋的方法，验证除一步转移以外的反应机制对重离子诱导转移反应的贡献是至关重要的。用运动学符合方法研究了导致^&lt；12&gt；C[2^+1]的单核子转移反应。与一步扭曲波Born近似理论的预测相反，推导出的^&lt；12&gt；C[2^+1]的四阶张量明显偏离零值。

The present study aims to develop a new experimental method of determining the spin of the nuclcar states of astrophysical interest by measuring the polarization tensors of the nuclei produced by the heavy-ion induced transfer reactions. The polarization tensors are being planned to be measured with high efficiency by observing the angular and energy broadenings of the reaction products due to the recoil of the particle or γ-ray emission using the two-dimensional position-sensitive silicon semiconductor detectors. The energy and position responses of the one-dimensional silicon detector have been investigated for α particles from a^<241> Am source and for ^<11>B and ^<12>C particles with kinetic energies ranging from several MeV to several ten MeV, produced by the ^<11>B+^<12>C reaction. Good linearity with the detected position was obtained by applying the gated integrator for both the energy and position signals. Energy ballistic deficit was also found to be negligible. The investigation of the response of the two-dimensional position sensitive detector is in progress.It was most important, for establishing the reliable method to determine the nuclear spin, to verify that the contribution of the reaction mechanisms other than the one-step transfer is of crucial importance in the heavy-ion induced transfer reactions. The one-nucleon transfer reactions leading to ^<12>C[2^+_1] have been investigated using the kinematical coincidence method. The deduced fourth rank tensor of ^<12>C[2^+_1] was found to significantly deviate from zero value, contrary to the prediction of the one-step distorted-wave Born approximation theory.