Counting correlation analysis of internal conversion electrons excited by nuclear-resonant synchrotron radiation and its application to surface study

本研究项目的目的是探测核共振同步辐射激发的内转换电子，并将其应用于固体表面的高级研究。该项目的第一步是研制时间分辨电子能量分析仪。我们已经设计了两种这样的光谱仪。一种是基于由三级椭球网格组成的延迟场分析器。这种分析仪的特点是探测角度宽，最适合于非常微弱的电子信号。我们利用雪崩光电二极管(雪崩光电二极管)来测量电子。雪崩光电倍增器的信噪比比传统的沟道型电子倍增器高出几百倍。另一种是带有特殊设计的条纹相机的半球偏转式分析器。该系统用于具有良好时间分辨率的角度分辨率测量。最大时间分辨率为20ps。在KEK的NE-3光束线上进行了内转换电子的测量。我们成功地测量了同步辐射辐照后的一个电子发射尾部。测量的样品为Fe_2BO_3。为了阐明延迟发射的本质和新的表面现象，继续对延迟电子发射进行测量。

The aim of this research project is detection of internal-conversion electrons excited by nuclear resonant synchrotron radiation and its application to advanced studies of solid surfaces.The first step of this project was a development of time-resolved electron energy analyzer. We have designed two kind of such spectrometer. One was based on a retarding field analyzer which consists of three stage ellipsoidal mesh grid. The special feature of this analyzer is a wide detection angle most preferable to the very weak electron signal. We have make use of an avalanche phot-diode (APD) to measure electrons. The signal to noise ratio of APD was superior to conventional channel-type electron multiplier by several hundreds. The other type is a hemispherical deflector-type analyzer combined with a specially designed streak-camera. This system is for a angular-resolved measurement with nice time-resolution. Maximum time resolution is 20ps.The measurement of internal-conversion electron was made at NE-3 beamline in KEK.We have successfully measured a tail of electron emission after irradiation of synchrotron radiation. The sample of this measurement was Fe_2BO_<3.> crystal. To elucidate the nature of delayd emission and new surface phenomena, the measurement of delayd electron emission is continued.