Simultaneous measurement of argon isotopes using microchannel plates

在40Ar/39Ar逐步加热实验中，需要进行快速测量以获得与时间无关的数据集，特别是对于小样本。本研究采用微通道板进行离子检测，并尝试同时测量从36Ar到40Ar的5种氩同位素。微通道板和位置敏感探测器的简单组合不适合用于超高真空系统，因为它需要在100℃以上的温度下烘烤。因此，我们采用了由和歌山工业大学Mizokawa博士和东京城市大学Shiromaru博士设计的带有加权耦合电容器（MBWC）的二维改进步步高方法，同时检测到大气中的36ar，38Ar和40Ar，但该系统不足以进行定量测量。大量的40Ar干扰了36Ar和38AT信号的同时测量，分别约为1 / 300和1 / 1600。该系统可实现二维离子检测，并能有效地调节质谱仪中各同位素的离子光学。设计一维线性通道电子链进行定量测量，与Dune公司的合作使其成为可能。结合二维系统和一个小型质谱仪与一维系统允许离子光学和高灵敏度定量氩质谱容易调谐。两种不同类型的质谱仪的独立发展现在产生了一种新的超小型高灵敏度质谱仪。用离子计数法测量来自位置敏感探测器的信号。开发了测量界面和程序，实现了测量的自动控制。控制和测量单元通过局域网电缆连接。完成了超低体积标准空气与高纯度气体分离的萃取净化系统。

In 40Ar/39Ar stepwise heating experiments, the fast measurements need to be carried out to obtain time-independent data sets, in particular for small samples. In this study, microchannel plates are used for ion detection, and simultaneous measurement of five argon isotopes from 36Ar to 40Ar was attempted.Simple combination of microchannel plates and a position sensitive detector is not suitable in an ultrahigh vacuum system because it needs baking at temperature over 100℃. Thus, we adopted the two dimensional Modified Backgammon method with Weighted coupling Capacitors(MBWC) designed by Drs Mizokawa at Wakayama College of Technology and Shiromaru at Tokyo Metropolitan University.36Ar,38Ar and 40Ar from atmosphere were detected simultaneously, but the system was not enough for quantitative measurements. The large volume of 40Ar disturbs the simultaneous measurement of 36Ar and 38AT signals which is approximately one three hundredth and one sixteen hundredth, respectively. The system allows two dimensional ion detection, and it is effective to adjust ion optics of each isotope in a mass spectrometer.Designing an one-dimensional chain of linear channeltron was considered to make quantitative measurements, and it became possible with coorperation with Dune Inc. Combining the two dimensional system and a small mass spectrometer with one dimensional system allow easy tuning of ion optics and highly sensitive quantitative argon mass spectrometry. Independent developments of two different types of mass spectromenters is now resulting in a new ultra small highly sensitive mass spectrometer.Signals from the position sensitive detector is measured by the ion counting method. The interface and program were developed as well as the automatic control for the measurement. The control and measurement units are connected via LAN cable. The extraction and purification system to separate ultra low volumes of the standard air and high purity gases were completed.