Development of an in-air high-resolution PIXE system

Abstract

A compact, wavelength-dispersive spectrometer was assembled for use in the high-resolution Particle-Induced X-ray Emission (PIXE) analysis in the air of atmospheric pressure. A proton beam up to 2.5 MeV was generated by a tandem accelerator. The proton beam was taken out to the atmosphere from vacuum through an aluminum foil, and collided against the target of analysis. X-ray emitted from the target was diffracted with a flat single crystal and detected by a Position-Sensitive Proportional Counter (PSPC). Both crystal for analysis and PSPC were mounted on a theta-2 thetha goniometer. The X-ray pathway was enveloped with a polyethylene bag and helium gas was enclosed in the bag. Lower detection limit of X-ray energy is 1 keV and simultaneously detectable angular range is 5 deg, which corresponds to 0.0157 deg for 1 channel of PSPC. Fused quartz (SiO2) was irradiated with proton beam of 2.2 MeV, and the emitted spectra of Si-alpha and Si-beta were measured. alpha(sub 1) line and alpha(sub 2) line of K-alpha emitted from KL(sub 0) of singly ionized state, and K-alpha satellite emitted from KL(sub 1) and KL(sub 2) of multiply ionized state were well resolved.

大気圧空気中における高分解能イオン励起X線(PIXE)分析に使用するための、コンパクトな波長分散分光器を組立てた。タンデム型加速器で陽子線(約2.5メガ電子ボルトまで)を発生させた。アルミ箔を透過させて真空中から大気中に陽子を取出し、分析ターゲットを照射した。ターゲットから放出されたX線を平板単結晶で回折し、位置有感比例カウンタ(PSPC)で検出した。θ-2θゴニオメータに分析結晶およびPSPCを据付けた。X線の通路をポリエチレン袋で包み、袋内にヘリウムガスを封入した。X線エネルギーの検出下限は1keVであり、同時検出の角度範囲幅は5度で、PSPCの1チャンネルが0.0157度に対応する。溶融石英(SiO2)を2.2MeV陽子で照射し、発生したSiαおよびSiβのスペクトルを計測した。単価イオン化状態KL(sup 0)から発生したKαのα(sub 1)、α(sub 2)線および多価イオン化状態KL(sup 1)、KL(sup 2)から放出されたKα衛星線を分解できた。