Development of Neutron Compton Scattering and Neutron Absorption Methods

本项目的目的是利用KEK （KENS）的脉冲散裂中子源，研制研制了已研究了很长时间的中子康普顿散射光谱仪和中子共振吸收光谱仪。本课题通过对电气系统、伽玛射线探测器和数据采集系统的进一步改进，成功地实现了两台性能良好的光谱仪。它们被命名为RAT和DOG，并安装在KENS中。RAT谱仪使获得基态波函数psi_0r（^^*）的信息成为可能。利用RAT，我们试图确定氢波函数在KHCO3中的空间分布。所得分布与理论分布非常接近，这可以从新的氢键化合物模型中推导出来。结果表明，氢势可以描述为摩斯型势和不对称势的叠加。狗谱仪可以测定杂质的浓度，甚至在小化合物中也可以观察到杂质的运动。例如，利用DOG，我们成功地确定了Sb/Si半导体中杂质Sb的浓度，并观察了Sb运动的温度依赖性。Sb的浓度约为0.001%。其次，我们观察了高Tc化合物La2-xBaxCuO4中杂质（Ba）运动的温度依赖性，发现在Tc周围有相当大的变化。第三，观察了激光辐照下杂质的运动，研究了电子-声子相互作用对杂质运动的影响。这三个典型的研究结果表明，狗狗可以打开一个新的科学领域的“杂质研究”，也为无损检测和微化学分析提供了进一步的可能性，这在工业上是非常重要的。

Aims of this project is to develop a neutron Compton scattering spectrometer and a neutron resonance absorption spectrometer, which have been investigated, for a long time, utilizing a pulsed spallation neutron source in KEK (KENS). By the further improvements of the electric system, gamma-ray detectors and data-acquisition system in this project, we succeeded to realize these two spectrometers with good performances. Those were named as RAT and DOG,and installed in KENS.RAT spectrometer makes it possible to obtain the information about the ground state wave function psi_0r (^^*). Using the RAT,We tried to determine the space-distribution of hydrogen wavefunction in KHCO3. The obtained distribution is very similar to the theoretical distribution, which can be derived from the new model for the hydrogen bonded compounds. This result show that the hydrogen potential can be described as a superimpose of the Mose-type potential and an asymmetric potential.DOG spectrometer makes it possible to determine the concentration of the impurity and to observe the impurity motion even in the small compound. For example, using the DOG,we succeeded to determine a concentration of the impurity Sb in the semi-conductor Sb/Si and to observe the temperature dependence of the Sb-motion. The concentration of Sb was about 0.001%. Second, we observed the temperature dependence of the impurity (Ba) motion in the high-Tc compound La2-xBaxCuO4, and found a considerable large change around the Tc. Third, we observed the impurity motion under the Laser-irradiation, and studied effects of the electron-phonon interaction on the impurity. The results of those three typical studies indicate that the DOG can open a new scientific field of the 'impurity research', and that the DOG can also provide the further possibility of nondestructive testing and microchemical analysis which are very important in the industrial.