抽运光中ASE噪声对OPCPA信噪比的影响

惯性约束核聚变快点火实验,要求拍瓦终端输出再压缩的高信噪比超短激光脉冲.在拍瓦前端光参变啁啾脉冲放大(OPCPA)阶段,抽运激光脉冲中由放大的自发辐射(ASE)噪声调制导致的电场强度振幅和相位的随机扰动.将会被传递到信号光的光谱E.使再压缩后主激光脉冲前后出现底座.降低了信号光的信噪比.数值模拟了抽运激光脉冲中ASE噪声对信噪比以及对时间底座的宽度的影响,并探讨了有利于提高超短激光脉冲信噪比的途径.     

Poisson baseline of net-charge fluctuations in relativistic heavy ion collisions

Taking doubly charged particles,positive-negative charge pair production and the effects of volume fluctuations into account,the Poisson baseline of the fluctuations of net-charge is studied.Within the Poisson baseline,the cumulants of net-charge are derived.Comparing to the Skellam baseline of net-charge,we infer that doubly charged particles broaden the distributions of net-charge,while positive-negative charge pairs narrow the distributions.Using the ratios of doubly charged particles and positive-negative charge pairs from neutral resonance decays to the total positive charges from THERMINATOR 2,the first four orders of moments and the corresponding moment products are calculated in the Poisson baseline for Au + Au collisions at (s_(NN))(1/2)= 200 GeV at RHIC/STAR.We find that the standard deviation is mainly influenced by the resonance decay,while the third and fourth order moments and corresponding moment products are mainly modified and fit the data of RHIC/STAR much better after including the effects of volume fluctuations.