基于本底扣除方法的海水伽马能谱分析研究OA

Lanthanum bromide LaBr3(Ce)scintillation detectors possess excellent energy resolution;however,ra-dioactive impurities in the crystal,such as ¹³⁸La,generate significant intrinsic background radiation.This interfer-ence severely affects the identification of characteristic peaks and the quantitative determination of radionuclide activities,such as ⁴⁰K and ¹³⁷Cs,in seawater.To enhance the applicability of LaBr3(Ce)detectors for marine radio-activity monitoring,this study developed a gamma-ray spectrometry method based on background subtraction.First,a NaI(Tl)scintillation detector,which has negligible intrinsic background,was used as a reference.Combined with the detector efficiency ratio obtained through Monte Carlo simulations,the intrinsic background contribution of the LaBr3(Ce)detector was experimentally separated and subtracted.Furthermore,by establishing a fitting correlation between the channel number and the full width at half maximum of characteristic peaks,the traditional statis-tics-sensitive nonlinear iterative peak-clipping background subtraction algorithm was improved by introducing an adaptive window width.This modification enabled effective removal of environmental background and Compton scattering contributions across the entire gamma spectrum.A 24 h field experiment conducted in the Badaxia sea area,Qingdao,demonstrated that,after processing with the proposed method,the relative error in ⁴⁰K activity de-termination was below 8%.Simultaneously,the minimum detectable activity of ¹³⁷Cs was substantially reduced from 0.234 Bq/L(before background subtraction)to 0.035 Bq/L,achieving performance comparable to that of the NaI(Tl)detector under identical measurement conditions.The spectral processing method developed in this study effectively mitigates the intrinsic background interference in LaBr3(Ce)detectors,providing a reliable technical approach for high-resolution in situ radionuclide detection in seawater.