X線エネルギー分布測定の研究

測定系レスポンス・マトリックスの作成と逆行列法による補正について

抄録

The primary X-ray energy distributions from a diagnostic unit were measured with a lithium drifted silicon detector of room temperature type. A pair of wedge shaped collimator was used to reduce the intensity of X-rays to measurable level. The resolution of the system with the detector was improved from 20 keV to 5.0keV for 122 keV gamma rays by a simple cooling apparatus and nitrogen vapor. Measured results for 241Am,57 C o, a n d 1 00 kVp X-rays with WKe, WKf 3 peaks are shown. The response matrix for the system, which is needed in estimating real energy distributions by correcting Gaussian broadening, energy dependence of photopeak efficiency and other effects, was mede by a computer from data of photopeak efficiency, measured FWHM and energy calibrations. Measured spectrum data were smoothed by regressions to second order polynomials on the basis of the least squares method. Corrections for the response of measuring system were performed by the inverse matrix method. The processes are described along with some lines of Fortran program.