Improvement on Analysis Method for X-Ray Arrival Spectrum From High-Altitude Nuclear Detonation

The study of the X-ray arrival spectrum of high-altitude nuclear detonation (HAND) shows that analytical methods offer advantages over Monte Carlo methods in terms of computation speed and the ability to invert the nuclear detonation source term. However, analytical methods have lower accuracy in calculating scattered X-rays in the spectrum arriving at the detector. To address this issue, an analytical method for correcting the X-ray arrival spectrum of HAND is proposed. This study employs a combined blackbody spectrum instead of a single blackbody spectrum to more accurately characterize the spectrum of the X-ray source from a hydrogen bomb detonation. A double-exponential fitting method is used instead of linear interpolation to obtain a more precise mass attenuation coefficient. Correction coefficients derived from Monte Carlo simulations to calibrate the arrival spectrum were corrected by the build-up factor (BUF). In the 2–130-keV energy range, the maximum relative errors between the Monte Carlo arrival spectrum and both the uncorrected for scattering and BUF-corrected arrival spectra are 84.9% and 100.2%, respectively. The proposed method reduces relative errors to within 15%, with a minimum error of less than 0.001%. In addition, its computation time is only 1/39600 of that of the Monte Carlo method. The proposed method provides a solid basis for designing, calibrating space-borne X-ray detectors and inverting the nuclear detonation yield.