APCAD - Analysis Program for the Continuous-Angle DSAM

We present a novel method for the analysis of Doppler-broadened γ-ray lineshapes observed by position-sensitive detector systems with the purpose to determine nuclear level lifetimes. This advance of the well-known Doppler-Shift Attenuation Method (DSAM) is specifically tailored to experiments employing γ-ray tracking detectors and takes advantage of the position resolution of these detector systems. The novel continuous-angle Doppler Shift Attenuation Method (caDSAM) is implemented in the comprehensive computer program APCAD for the calculation of Doppler-broadened γ-ray lineshapes, their fit to experimental data and extraction of level lifetimes. Extensions of the method qualifying it for measurements with radioactive and relativistic ion beams as well as for the measurement of “long” level lifetimes of the order of ∼200 ps are presented.我们提出了一种全新方法，用于分析由位置灵敏探测器系统（position-sensitive detector systems）观测到的多普勒展宽γ射线线形（Doppler-broadened γ-ray lineshapes），以测定核能级寿命（nuclear level lifetimes）。该方法是对经典多普勒位移衰减法（Doppler-Shift Attenuation Method，DSAM）的改进，专门适配采用γ射线追踪探测器（γ-ray tracking detectors）的实验，并利用了此类探测器系统的位置分辨能力。我们将这种新型连续角多普勒位移衰减法（continuous-angle Doppler Shift Attenuation Method，caDSAM）集成于综合计算机程序APCAD中，用于计算多普勒展宽γ射线线形、将其与实验数据拟合并提取能级寿命（level lifetimes）。此外，本文还阐述了该方法的拓展应用场景，使其可用于放射性相对论离子束（radioactive and relativistic ion beams）的相关测量，以及测定约200皮秒量级的"长"能级寿命。