Influence of Detector Misalingnment on the Ħ Assembly X-Ray Stress Measurement Using a Position Sensitive Proportional Counter as a Detector
Toru GOTO and Yu GONG
Abstract: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 W assembly X-ray stress measurement. The stress errors Dsrd, Dstd and Dskd due to the translation td in the direction of goniometer radius, the translation rd in the direction of diffraction angle and the rotation kd, respectively, were calculated as the value of measured stress sx subtracted by specimen stress s and intrinsic stress sc. It was found that Dsrd, Dstd and Dskd are expressed as a linear relation of rd, td and kd, respectively. The slope of the relation depends on the collimator dimensions, goniometer radius and specimen stress. However, the absolute value of Dsrd, Dstd and Dskd 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 compar ed with those due to specimen mis-setting and collimator misalignment. Key Words:X-ray stress measurement, PSPC, Error in stress measurement, Detector misalignment, Collimator misalignment, Specimen mis-setting