Research of Nuclear Excitation by Electron Transition on ^<189>Os

在2001财政年度，我们开发了一个内转换电子探测器与网状硅雪崩光电二极管（硅APD）。该探测器有两个单片Si-APD阵列的thitee像素（3毫米直径），安装在一个真空室。我们使用8.4 keV X射线在光子工厂的束线BL-14 A处测试了探测器。结果表明，由于探测区域内增益cn位置的差异较大，硅APD阵列的能量分辨率比普通器件差。虽然我们不能使用新的Si-APD，但我们试图观察^ Ir的电子跃迁核激发（NEET）<193>，正如我们计划的那样，在真空室中使用一个Si-APD的探测器。实验在SPring-8的BL 09 XU进行。我们成功地观测到了NEET，其几率小于^ Au的十分之一<197>。我们的NEET概率结果为（2.8±0.2）×10^<-9>，而最近的计算值为2.0×10^<-9>。在2002财年，硅APD阵列进行了改进，并在BL-14 A上再次进行了测试。能量分辨率得到改善，并将阵列安装在探测器中。然而，<189>由于改进Si-APD的延迟以及在我们在SPring-8上进行实验的一段时间内加速器中的故障，我们没有机会在^O上执行NEET实验。在2002财政年度之后，在2003年4月，我们试图在<I89>SPring-8的BL 09 XU观测^ Os上的NEET。在实验中，我们使用了另一个Si-APD，因为Si-APD阵列的信噪比比我们预期的要小。在<189>K壳层电离过程中，用该探测器仍然没有观察到^ Os上的NEET。将继续改进探测器，以提高信噪比。

In FY2001, we developed an internal-conversion electron detector with nety silicon avalanche photodiodes (Si-APDs). The detector had two monolithic Si-APD arrays ofthitee pixels (3 mm in diameter), installed in a vacuum chamber. We tested the detector at beamline BL-14A of the Photon Factory using 8.4-keV x-rays. The results had a problem that the energy resolution ofthe Si-APD array was worse than that of a normal device due to a large difference of gains cn position in the detection area. Though we could not use the new Si-APDs, we tried to observe; the nuclear excitation by electrontransition (NEET) on ^<193>Ir, as we scheduled in our plan, with the detector that had one Si-APD in the vacuum chamber. The experiment was done at BL09XU of the SPring-8. We successfully observed NEET, of which probability was less than one tenth otfthat on ^<197>Au. Ourresult of the NEET probability was (2.8±0.2)×10^<-9>, while a recent calculation presented a value of 2.0×10^<-9>. The difference between the results will be discussed.In FY2002, the Si-APD array was improved and tested again at BL-14A. The energy resolution became better and the arrays were installed in the detector. However, we did not have a chance for executing an experiment for NEET on ^<189>Os due to a delay of improving the Si-APD and due to atrouble in the accelerator within a period of our experiment at the SPring-8. After FY2002, in April 2003, we have tried to observe NEET on ^<I89>Os at BL09XU of the SPring-8. In the experiment, we used another Si-APDs because a signal-to-noise ratio of the Si-APD array was smaller than that we expected. With the detector, NEET on ^<189>Os was still not observed in the K-shell ionization. The improvement in the detector for a better signal-to-noise ratio will be continued.