Emission Mossbauer Spectroscopy of ^<237>Np Probe in Uranium Compounds.

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This research project was started in order to investigate the physical properties of uranium compounds with strong-correlated electrons by emission ^<237>Np Mossbauer spectroscopy on the basis of new idea that parent ^<237>U nuclei as probes are introduced in U compounds through ^<238>U(gamma, n) reaction. It is also a purpose to establish the emission ^<237>Np Mossbauer spectroscopy to be general and powerful tool for material researches of actinide compounds and alloys. Therefore, the more specific purpose of this work is to develop and construct a spectrometer with sufficient ability for the emission ^<237>Np Mossbauer spectroscopy. The results are summarized as follows.1. A liquid-helium cryostat for the emission ^<237>Np Mossbauer spectroscopy was constructed. In the cryostat, a standard ^<237>NpO_2 absorber is maintained at a constant temperature of 78 K.A sample Mossbauer source put on a long stem whose temperature is controlled between 1.5 K and room temperature can be driven by a precise velocity wave form of *100 mm/sec.2. In the geometry mentioned above, the condition for precise drive of source is surveyed using a absolute velocity calibrator using a laser interferometer which is put in the system in order to observe regularly the precise velocity.3. From the view point of precise drive and velocity calibration, it was confirmed repeatedly that the whole system satisfies the ability demanded for the emission ^<237>Np Mossbauer spectroscopy through measurements of the popular ^<57>Fe Mossbauer effects and the time spectra of interference fringes. Consequently, the whole spectrometer system with sufficient ability for the emission ^<237>Np Mossbauer spectroscopy was completed by the present research project.