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Application of the alpha transfer reactions at incident energies below the Coulomb barrier to determination of the astrophysical reaction rate

应用入射能量低于库仑势垒的α转移反应来确定天体物理反应速率

基本信息

批准号：
13640292
负责人：
IKEDA Nobuo
金额：
$ 2.24万
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：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

The present study aims to develop a new experimental method of determining the astrophysical nuclear reaction rate by the measurement of the heavy-ion induced transfer reactions at incident energies below the Coulomb barrier with the recoil mass separator which has recently been developed at Kyushu University tandem accelerator laboratory. This separator is designed to achieve highest possible capability of the background rejection in the condition of inverse kinematics. Application of the proposed method to the deduction of the rate of the α-particle induced radiative capture reactions which cross sections are too small to measure directly at the accelerator facilities is expected to provide rich and new information on the evolution of the massive stars.Instrumental developments have been carried out at both the accelerator and the measuring devices for facilitating the observation of the reaction products emitted at center-of-mass angles of 0 and 180 degrees from the transfer reactions in the condition of the inverse kinematics with negligible contamination of the primary beam particles and the background particles associated with a primary beam. At the accelerator, the beam pulsing system and the windowless gas stripper have been developed to derive a pulsed beam of good emittance, essential to the elimination of the background. The detailed investigations on the performance of the mass separator and the response of a silicon semiconductor detector for low energy light-heavy particles have assured the background rejection capability of the measuring system enough to realize the unambiguous measurement. With these developments and investigations, we are about to start the experiments to examine the applicability of the transfer reaction data at low incident energies to the extraction of the astrophysical nuclear reaction rate.

本研究旨在开发一种新的实验方法，通过使用九州大学串联加速器实验室最近开发的反冲质量分离器测量库仑势垒以下入射能量下的重离子诱导转移反应来确定天体物理核反应速率。该分离器旨在在逆运动学条件下实现尽可能高的背景抑制能力。应用所提出的方法来推导截面太小而无法在加速器设施上直接测量的α粒子诱发的辐射捕获反应的速率，有望为大质量恒星的演化提供丰富的新信息。加速器和测量装置都进行了仪器开发，以便于观测在0度和180度质心角发射的反应产物。来自逆运动学条件下的转移反应，主束粒子和与主束相关的背景粒子的污染可忽略不计。在加速器处，开发了光束脉冲系统和无窗气体剥离器，以产生具有良好发射率的脉冲光束，这对于消除背景至关重要。对质量分离器性能和硅半导体探测器对低能轻重粒子响应的详细研究保证了测量系统的背景抑制能力足以实现明确的测量。随着这些进展和研究，我们即将开始实验来检验低入射能量下的转移反应数据对于提取天体物理核反应速率的适用性。