Development of Neutron Compton Scattering and Neutron Absorption Methods

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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.