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.本研究提出一种新方法，用于分析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（γ-ray）线形，以实现核能级寿命的测定。该方法是经典多普勒位移衰减法（Doppler-Shift Attenuation Method，DSAM）的改进版本，专门针对采用γ射线跟踪探测器（γ-ray tracking detectors）的实验设计，并充分利用此类探测器系统的位置分辨能力。该新型连续角多普勒位移衰减法（continuous-angle Doppler Shift Attenuation Method，caDSAM）已集成于综合计算机程序APCAD中，可完成多普勒展宽γ射线线形的计算、与实验数据的拟合以及能级寿命的提取。本研究还提出了该方法的扩展应用，使其可适用于放射性离子束与相对论性离子束的实验测量，以及对量级约200皮秒（ps）的‘长’能级寿命的测定。