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Coulomb Excitation with Fluorine-1 8 Isomeric Secondary Beam

氟 1 8 异构二次光束库仑激发

基本信息

批准号：
12640282
负责人：
MORIKAWA Tsuneyasu
金额：
$ 1.98万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

In order to precisely determine the astro-physical nuclear reaction rate at very low energy, which is important for the study of stellar evolutions, a high-resolution recoil mass separator (RMS) has been constructed at the Kyushu university tandem accelerator laboratory (KUTL). By using the differences in the energy and momentum, the RMS is capable of separating with high S/N ratio the reaction products from the primary beams. It is possible to produce the secondary beams of unstable nuclei by using this KUTL RMS system.In the present study, aiming the realization of the spectroscopy with secondary beam induced reactions, we developed the method for production of the secondary beams. The method employs the fusion evaporation reactions of inverse kinematics where heavy projectile from the accelerator and the light target nucleus are combined. By using the inverse kinematics, the reaction products are recoiled into a limited region of forward solid angle with a kinematic energies enough for the secondary reactions.Since the fluorine-18 secondary beam was turned out to be very difficult to produce, due to the limitations in the accelerators and the RMS, we then focused on the development of the sodium-22 secondary beam which is produced by fluorine-19 beam and helium-4 target. It was confirmed that with the present system it is possible to produce the sodium-22 secondary beam at an intensity of more than 10000 cps without any significant contamination originating from the primary beam.We also developed the charged particle detection/monitor system for the secondary beam experiments. The detectors are made of plastic scintillators coupled to position sensitive photo multiplier tubes. The system has the high endurance against irradiation and the fast timing characteristics suitable for the TOP measurements. Further development will be made to realize the spectroscopy by Coulomb excitation experiments with secondary beams.

为了精确确定极低能量下的天体物理核反应速率（这对于恒星演化研究非常重要），九州大学串联加速器实验室（KUTL）建造了高分辨率反冲质量分离器（RMS）。利用能量和动量的差异，RMS能够以高的S/N比从初级束中分离反应产物。利用KUTL RMS系统可以产生不稳定核的次级束，本文以实现次级束感生反应光谱学为目标，研究了产生次级束的方法。该方法采用逆运动学的聚变蒸发反应，其中来自加速器的重射弹和轻靶核相结合。利用逆运动学方法，反应产物被反冲到一个有限的正立体角区域，并具有足够的动能进行二次反应。由于加速器和RMS的限制，F-18二次束很难产生，然后，我们着重研究了由氟-19束流和氦-4靶产生的钠-22次级束流。实验结果表明，利用本系统可以产生强度大于10000 cps的钠-22次级束流，而不会产生来自初级束流的任何明显的污染，并研制了用于次级束流实验的带电粒子探测/监测系统。探测器由塑料放大器和位置敏感光电倍增管组成。该系统具有高的抗辐照能力和快速的定时特性，适合于TOP测量。利用次级束的库仑激发实验实现光谱学将是进一步的发展。