Development of online event selection program for the fluorescence detector of the Telescope Array experiment

在望远镜阵列实验中，空气荧光探测器用于观测超高能宇宙射线。为了重建一次能量小于10**18 eV的最小信号，地面探测器记录的空气淋点粒子到达地面的时间信息可用于空气荧光探测器的事件重建。为了有效地获得表面探测器的低能量事件，设计了一个外部触发器（从空气荧光探测器到表面探测器）。我们研究了这个外部触发器来提高它的性能。研究了用外部触发得到的观测事件。观测到初级能量为10**17.7 ~ 10**18.3 eV的宇宙射线的初步能谱。

Air fluorescence detectors are employed to observe ultra high energy cosmic rays in the Telescope Array experiment. To reconstruct minimum signals with the primary energy less than 10**18 eV, arrival time information of air shower particles on the ground recorded by the surface detectors is useful for event reconstruction of the air fluorescence detectors.An external trigger (from air fluorescence detector to surface detector) was installed to obtain lower energy events of surface detector effectively. We studied this external trigger to improve its performance. The observed events which were obtained with the external trigger are studied. The preliminary energy spectrum of cosmic rays with the primary energy of 10**17.7 to 10**18.3 eV is observed.