排序方式: 共有27条查询结果,搜索用时 15 毫秒
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基于重离子储存环建立的等时性质谱术(IMS)是测量远离稳定线核素质量的有效工具。但是,采用常规IMS测量缺中子一侧的核素质量时,发现Tz=-1/2和Tz=-1核素的质量测量结果在宽时域范围内存在系统性偏差。本工作利用CSRe直线段上的双飞行时间(TOF)探测器,同时测量了循环离子的周期和速度。利用这些实验信息,对常规IMS质量测量中出现的系统性偏差进行了研究。发现系统偏差是由于储存的离子动量分布不对称以及储存环能量转变参数γt非恒定造成的。在离线数据处理时,发现通过限制动量接收度的大小,可以消除常规IMS质量测量中的系统偏差。这一结果对采用常规IMS进行质量测量具有重要参考价值和指导意义。 相似文献
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根据几种常用放射性核素的寿命计算方法,通过模拟数据研究了直接拟合法、对数时间法、极大似然法、观测时间受限时的极大似然法等四种寿命计算方法的适用范围。当观测时间不受限时,研究了在不同计数下寿命计算方法的适用范围。当观测时间受限时,研究了在不同观测时间窗口下寿命计算方法的适用范围。模拟中选用全剥离离子94mRu44+作为目标核素,得到了不同计数及不同观测时间窗口下的寿命及其误差,并给出了四种方法的适用范围。94mRu44+寿命的模拟结果与在兰州等时性质量谱仪上获得的实验结果在一倍标准偏差范围内一致,从而进一步验证了寿命计算方法的适用范围及模拟数据的可靠性。该模拟结果可为寿命测量实验设计提供理论依据和参考。 相似文献
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The combination of in-flight fragment separator and the isochronous mass spectrometry(IMS) in storage rings have been proven to be a powerful tool for the precision mass measurements of shortlived exotic nuclei. In IMS, the mass-over-charge ratio is only related to the revolution period of stored ions, and the relative mass resolution can reach up to the order of 10−6. However, the instability of the magnetic field of storage ring deteriorates the resolution of revolution period, making it very difficult to distinguish the ions with very close mass-over-charge ratio via their revolution periods. To improve the resolution of revolution periods, a new method of weighted shift correction (WSC) has been developed to accurately correct the influence of the magnetic field instabilities in the isochronous mass measurements of 58Ni projectile fragments. By using the new method, the influence of unstable magnetic fields can be greatly reduced, and the mass resolution can be improved by a factor up to 1.7. Moreover, for the ions that still cannot be distinguished after correcting the magnetic field instabilities, we developed a new method of pulse height analysis for particle identification. By analyzing the mean pulse amplitude of each ion from the timing detector, the stored ions with close mass-over-charge ratios but different charge states such as 34Ar and 51Co can be identified, and thus the mass of 51Co can be determined. The charge-resolved IMS may be helpful in the future experiments of isochronous mass measurement even for N =Z nuclei. 相似文献
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