Fig. 1. Energy spectra of X-rays passing through different materials (a) 0.1 cm, (b) 0.6 cm

Fig. 2. Response relationship between X-rays and thickness of experimental material (a) Low-energy window, (b) High-energy window

Fig. 3. Structure diagram of four-detector X-ray density-logging instrument

Fig. 4. Effect of internal shield of instrument on count rate of short-spacing detector (a) and long-spacing detector (b)

Fig. 5. Effect of shields thickness between detectors on count rate

Fig. 6. Effect of detector back shield thickness on count rate