Development of Light Detectors for Conversion Electron Mossbauer Spectroscopy and Nuclear Scattering of Synchrotron Radiation

1)阐明了新型穆斯堡尔谱仪中安装的快速响应雅普闪烁探测器的性能。2）建立了<57>Fe穆斯堡尔共振闪烁可移动计数器的测量系统。在发射穆斯堡尔谱（EMS）中，S/N效率为400%。即使是常规源的1/10放射性也可以用来测量穆斯堡尔谱，其能量分辨率优于常规方法。3）在SPring 8装置上进行了核共振非弹性散射（NIS）实验。实验结果表明，采用8个APD探测器，在90 min内获得了时间分辨率小于1 ns的NIS光谱。该程序是由核非弹性散射谱估算部分声子态密度的程序。4）测量了（Ba，Sr）（Fe，Co）O_（3-δ）和（Sr，Ca）（Fe，Co）O_（3-δ）的NIS谱。结果表明，在δ=0.5的钙钛矿中观察到8 meV的声子峰，而在钙钛矿中没有观察到8 meV的声子峰。NIS对分析2 - 60 meV范围内的振动态密度是非常有效的。5）利用自行研制的转换电子穆斯堡尔探测器，通过选择电子能量，对不锈钢氧化后的表面和界面进行了表征。通过对超精细分布的分析发现，铁素体不锈钢界面受Cr向表面扩散的影响。溅射奥氏体不锈钢沉积的不锈钢膜由铁素体相组成。内部磁场因加热而增强，在500℃时铁素体相转变为顺磁性奥氏体相。对不同温度下制备的厚度为10 nm的氧化物薄膜的状态也进行了估算。

1) The properties of YAP scintillation detector with fast response installed into new Mossbauer spectrometer were clarified.2) Measurement system for ^<57>Fe Mossbauer resonant scintillation movable counter, was established. In the emission Mossbauer spectra (EMS), the efficiency of S/N was 400%. Even the 1/10 radioactivity of conventional source could be found to measure Mossbauer spectra with the better energy resolution than a conventional method.3) Nuclear resonant inelastic scattering (NIS) was carried out in SPring 8 facility. It was confirmed that NIS spectra were obtained in 90 min using 8 detectors of APD with less than 1 ns time resolution. The program was developed for partial phonon density of states estimated from the nuclear inelastic scattering spectra. Lamb-Mossbauer factors at various temperatures, which are indispensable for quantitative analysis, were obtained from phonon density of states on the base of Debye model.4) NIS spectra of various perovskite such as (Ba, Sr)(Fe, Co)O_<3-δ> and (Sr, Ca) (Fe,Co)O_<3-δ> were measured. It was found that the phonon peak of 8 meV was observed in brownmillerite with δ=0.5, but not in perovskite. NIS is very effective for analysis of the vibrational densities of states from 2 meV to 60 meV.5) The surface and interface of stainless steel oxidized were characterized by selecting die electron energy using a conversion electron Mossbauer detector developed. It is found from the analysis of hyperfine distribution that the interface of ferrite stainless steel was affected by the diffusion of Cr to the surface. The stainless steel film as deposited by sputtering austenitic stainless steel was consisted of ferritic phase. The inner magnetic fields increased by heating., and the ferritic phase was converted into paramagnetic austenitic phase at 500℃. The states of thin oxide films with 10 nm in thickness produced at various temperatures were also estimated.