Systematic errors in energy determination of ultrahigh-energy cosmic rays by fluorescence method

空气荧光技术被用来探测超高能宇宙射线，并估计其能量。最重要的是由不同密度和温度的空气中的电子激发产生的光子产额。本研究的目的是：1.使用β源研究在氮气和干燥空气中辐射的光子产额和激发态寿命随压力的变化关系。通过将实验结果应用于正在进行的HiRes和Auger等实验以及EUSO等空间站计划中的项目，估计了宇宙线能量测定的系统误差。对于(1)，测量了300 nm至430 nm之间15个波段的光子产额。在1013hPa20℃条件下，在0.85 MeV电子激发下，在300~406 nm范围内的总光子产额为3.81±0.13光子/米。对于(2)，我们已经展示了使用能量沉积而不是探测器相机中每个角盒的带电粒子数量来估计初级宇宙线的新方法。给出了每个波长的参数，用于估算能量沉积。

The air fluorescence technique is used to detect ultrahigh-energy cosmic rays, and to estimate their energy. Of fundamental importance is the photon yield due to excitation by electrons in air of various densities and temperatures. The purposes of this research are :1. Using a ^<90>Sr β source to study the pressure dependence of photon yields and the life times of the excited states, for radiation in nitrogen and dry air.2. By applying the experimental results to the on-going experiments such as HiRes and Auger, and the planed project from the space-station such as EUSO, to estimate the systematic errors in energy determination of cosmic rays.For (1), the photon yields in 15 wave bands between 300nm and 430nm have been determined. The total photon yield between 300nm and 406nm (used in most experiments) in excited by 0.85MeV electron is 3.81±0.13 photons per meter at 1013hPa and 20℃. For (2), we have shown the new method to use energy deposition rather than the number of charged particles for each angular bin in the camera of the detector to estimate the primary cosmic rays. Parameters in each wavelength have been given for application to estimate the energy deposition.