Influence of Detector Misalignment on the OMEGA Assembly X-Ray Stress Measurement Using a Position Sensitive Proportional Counter as a Detector

摘要

Recently, the position sensitive proportional counter (PSPC) has been becoming popular as a detector for the X-ray stress measurement. However, little information is available in the literature regarding the effects of systematic errors such as specimen mis-setting, collimator misalignment and detector misalignment etc. on the stress measurement using the PSPC. In this paper, the detector misalignment is discussed using a model and a simulation method of the OMEGA assembly X-ray stress measurement. The stress errors DELTA sigma_(rd), DELTA sigma_(td) and DELTA sigma_(kd) due to the translation r_d in the direction of goniometer radius, the translation t_d in the direction of diffraction angle and the rotation k_d, respectively, were calculated as the value of measured stress sigma_x subtracted by specimen stress sigma and intrinsic stress sigma_c. it was found that DELTA sigma__(rd), DELTA sigma_(td) and DELTA sigma_(kd) are expressed as a linear relation of r_d, t_d and k_d, respectively. The slope of the relation depends on the collimator dimensions, goniometer radius and specimen stress. However, the absolute value of DELTA sigma_(rd), DELTA sigma_(td) and DELTA sigma_(kd) were found extremely small for the conditions examined. If the detector is misaligned under the combination of translations and rotation, the stress error is the sum of the errors due to translations and rotation. If the stress is measured under detector misalignment with specimen mis-setting, the stress error is the sum of the errors due to detector misalignment and specimen mis-setting. Under the detector misalignment with collimator misalignment, the stress error is the sum of the errors due to detector misalignment and collimator misalignment. It was concluded that the stress error due to detector misalignment is negligibly small when compared with those due to specimen mis-setting and collimator misalignment.