Spectroscopy of the Proton Rich Nuclei by the use of Secondary Beams and Direct Observation of Giant M1 Resonance

使用二次光束对富质子核进行光谱分析并直接观察巨 M1 共振

基本信息

批准号：
01460020
负责人：
SHIMODA Tadashi
金额：
$ 4.03万
依托单位：
Osaka University, Faculty of General Education
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

We have previously succeeded in commissioning the recoil separator CARP at the Research Center for Nuclear Physics, Osaka University. This device allows us to mass-separate nuclear reaction products and transport them into the detecting position in the form of a secondary beam. Considering the advantage of the use of the separator, the objective of the present investigation was set at the accurate measurement of the Gamow-Teller (GT) beta-transition rates of the proton rich T_z = -3/2 and -2 nuclei in the sd-shell. This was to promote deeper understanding of the quenching mechanism of the giant M1 resonance, by facilitating the detailed comparison of the GT-strength between the theory and experiment for a wide range of nuclei far off the beta-stability line.In the early stage of the investigation, an emphasis was placed on the achievement of a large solid angle of the recoil separator for the reaction products and on the construction of a detector system which is highly sensitive to the beta-rays and associated radiations with the decay of the products but insensitive to the external background radiations. Following these developments of the apparatus, a gain of a factor of no smaller than 20 over the previous experimental set-up was found achieved in the overall collection efficiency of the data.Taking account of the relatively large production cross sections of the T_z = -3/2 nuclei, the first experiment was determined to be carried out on ^<13>O, ^<21>Mg, ^<25>Si, ^<21>S, ^<37>Ca and ^<41>Ti. We have successfully completed the measurements for all these T_z = -3/2 nuclei by the time of preparing this report. The analysis of the data has been completed for ^<25>Si and the quenching factor of the GT-strength was determined. An unexpectedly large concentration of the GT-strength was found in the isobaric analog state of ^<25>Si in ^<25>Al. For the other nuclei, the data analysis is under way. The experiments for the T_z = -2 nuclei are about to start.

我们此前已在大阪大学核物理研究中心成功调试了反冲分离器 CARP。该装置使我们能够对核反应产物进行质量分离，并以二次光束的形式将它们输送到检测位置。考虑到使用分离器的优点，本研究的目标是准确测量富质子 T_z = -3/2 和 -2 原子核的 Gamow-Teller (GT) β 跃迁速率。 SD-外壳。这是为了促进对巨 M1 共振猝灭机制的更深入理解，通过促进理论与实验之间对远离 β 稳定线的大范围核的 GT 强度的详细比较。该研究的重点是实现反应产物反冲分离器的大立体角，以及构建对β射线和与产物衰变相关的辐射高度敏感的探测器系统，但对外部背景不敏感辐射。随着设备的这些发展，数据的整体收集效率比之前的实验设置提高了不小于 20 倍。考虑到 T_z = - 相对较大的生产横截面3/2核，第一个实验确定在^ 13 O、^ 21 Mg、^ 25 Si、^ 21 S、^ 37 Ca和^<41>钛。在准备本报告时，我们已经成功完成了所有这些 T_z = -3/2 原子核的测量。对于 25 Si 的数据分析已经完成，并且确定了 GT 强度的猝灭因子。在^ 25 Al中的^ 25 Si的同量异位类似物状态中发现了意想不到的大浓度的GT强度。对于其他核，数据分析正在进行中。 T_z = -2 原子核的实验即将开始。