Direct measurement method of micro-beam X-ray focus based on array detector

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2020-05, Vol.963, p.163751, Article 163751
• Main Authors: Yang, Qiang, Deng, Zhi-peng, Shi, Jia-lei, Ao, Hai-qi, Lai, Wan-chang
• Format: Article
• Language: English
• Subjects: Array detector; Directly measure; Focal spot size; Microbeam fluorescence
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2020.163751

A method for directly measuring the focal spot size and minimum focus position output by micro-beam X-ray is proposed. An experimental device based on portable micro X-ray source and capillary X-ray lens is built, and the experiments are carried out at different distances and under different tube voltages. The measured results are compared with the knife-edge scanning method. The results show: the focal spot size and minimum focus position of X-ray lens are 87μm and 9.798 cm respectively by using an array detector. X-ray array detector can directly measure the size of focal spot and predict the position of the minimum focus. It has the advantages of real-time measurement, available two-dimensional distribution, high cost performance and high efficiency. The device can predict the minimum focus position better, but the measured focal spot size is larger than it measured by knife-edge scanning method due to the influence of the pixel size and energy response of the array detector. The measurement results are related to the size of the pixel unit, measurement threshold and exposure time of an array detector.