Radiation imaging by a micro photomultiplier using micromachining thchnique

使用微加工技术的微型光电倍增管进行辐射成像

基本信息

批准号：
07458099
负责人：
NAKAZAWA Masaharu
金额：
$ 4.29万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

We have investigated a new position sensitive array type photomultiplier which can be used for a radiation imaging detector operated at very high counting rate such as in SR facilities. This idea is based on miniaturizing a standard photomultiplier tube (PMT). Many miniature holes are formed on the dynode using micromachining technique. These dynode plates are layred with insulators, and bias voltages are applied among plates. Incident electrons to the first dynode plate make secondary electrons on the dynode hole, and these emitted electrons are attracted to the next layred dynode plate. The successive secondary electron emissions occur in each pixel that works like an independent photomultiplier. As to the structure of this dynode hole, two different types of plate dynodes were designed. One had many pyramid shape penetrating holes (100mum*100mum size) which were formed by anisotropic Si etching, and the other had many slanting holes (100mum*80mum size) which were molded by a LIGA like process. Calculated maximum multiplication factors after 12 stages were 10^5 for the pyramid type and 10^7 for the slanting hole type. Both type of dynode plates are fabricated. The electron multiplication factor per one dynode was measured using two dynode plates of each hole configuration. It was 1.62 at the bias voltage of 150V in pyramid hole type, and 2.14 at 400V in slanting hole type. These values agreed with 1.7 (pyramid) and 2.19 (slanting) obtained by Monte Carlo simulation. In order to study the feasibility of a multi-layred device, four pyramid dynodes are stacked in one device. Unfortunately, a charge-up effect was found for the silicon multilayred device which extremely lowers the multiplication facotor. Although this effect must be investigated and overcome, we ensured the feasibility of multilayred devices.

我们已经研究了一种新的位置敏感阵列型光电倍增仪，该型号可用于以非常高的计数速率（例如在SR设施）运行的辐射成像检测器。这个想法基于将标准光电倍增管（PMT）的微型化。使用微加工技术在朝代上形成了许多微型孔。这些驱动器板与绝缘子一起放置，并且板之间施加偏置电压。第一个驱动器板的入射电子在驱动器孔上产生二级电子，这些发射的电子被下一个躺形板吸引。连续的二级电子排放出现在每个像素中的工作，就像独立的光电层流一样。至于该驱动器孔的结构，设计了两种不同类型的板驱动器。一个由各向异性的Si蚀刻形成许多金字塔形状穿透孔（100MUM*100MUM尺寸），另一个是由Liga类似的过程成型的许多倾斜孔（100MUM*80MUM尺寸）。 12阶段后计算出的最大乘法因子为10^5的金字塔类型为10^5，倾斜孔类型为10^7。两种类型的下板均制造。使用每个孔构型的两个驱动器板测量每个一个点的电子乘法系数。在金字塔孔类型150V的偏置电压下为1.62，在倾斜孔中为400V时为2.14。这些值与蒙特卡洛模拟获得的1.7（金字塔）和2.19（倾斜）一致。为了研究多层设备的可行性，将四个金字塔驱动器堆叠在一个设备中。不幸的是，发现了硅多层设备的充电效果，该设备极大地降低了乘法面孔。尽管必须研究和克服这种效果，但我们确保了多层设备的可行性。