Detector efficiency and exposure of Tunka-Rex for cosmic-ray air showers-猫眼课题宝

Tunka-Rex 宇宙射线空气簇射的探测器效率和曝光

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2017

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作者：

O. Fedorov;P. Bezyazeekov;N. Budnev;D. Chernykh;O. Gress;A. Haungs;R. Hiller;T. Huege;Y. Kazarina;M. Kleifges;E. Korosteleva;D. Kostunin;O. Kromer;L. Kuzmichev;V. Lenok;N. Lubsandorzhiev;T. Marshalkina;R. Mirgazov;R. Monkhoev;E. Osipova;A. Pakhorukov;L. Pankov;V. Prosin;F. Schroder;A. Zagorodnikov

Tunka-Rex（Tunka 无线电扩展）是位于西伯利亚的用于宇宙射线探测的天线阵列。之前使用 Tunka-Rex 对宇宙射线进行的研究表明，在确定初级粒子的能量方面具有高精度，并且可以重建流星雨最大值的深度。下一步是重建宇宙射线的质量成分和能谱。该任务中出现的主要问题之一是估计仪器的检测效率以及观测结果的曝光。探测效率取决于初级宇宙射线的特性，例如能量和到达方向，以及仪器的许多参数：阵列密度、接收天线的效率、信号探测阈值、数据采集接受和触发特性。不仅如此，探测器的配置随时间而变化。在测量过程中，探测器的某些部分可能会提供损坏的数据或有时无法运行。在估计检测效率时应考虑所有这些特征。对于每个能量和到达方向，我们估计仪器的检测概率和有效面积。为了估计流星雨的检测概率，我们使用一个简单的蒙特卡罗模型，该模型根据主要能量和到达方向（考虑到地球磁场的几何形状）来预测无线电发射足迹的大小。结合这些方法，我们计算每次运行的事件统计数据和曝光率。这是首次对不规则大型射电阵列的暴露进行精确研究，考虑到最重要的探测特征，该研究将用于通过 Tunka-Rex 测量初级宇宙射线光谱。

Tunka-Rex (Tunka Radio Extension) is an antenna array for cosmic-ray detection located in Siberia. Previous studies of cosmic rays with Tunka-Rex have shown high precision in determining the energy of the primary particle and the possibility to reconstruct the depth of the shower maximum. The next step is the reconstruction of the mass composition and the energy spectrum of cosmic rays. One of the main problems appearing within this task is to estimate the detection efficiency of the instrument, and the exposure of the observations. The detection efficiency depends on properties of the primary cosmic rays, such as energy and arrival direction, as well as on many parameters of the instrument: density of the array, efficiency of the receiving antennas, signal-detection threshold, data-acquisition acceptance, and trigger properties. More than that, the configuration of detector changes with time. During the measurements some parts of the detector can provide corrupted data or sometimes do not operate. All these features should be taken into account for an estimation of the detection efficiency. For each energy and arrival direction we estimate the detection probability and effective area of the instrument. To estimate the detection probability of a shower we use a simple Monte Carlo model, which predicts the size of the footprint of the radio emission as function of the primary energy and arrival direction (taking into account the geometry of Earth's magnetic field). Combining these approaches we calculate the event statistics and exposure for each run. This is the first accurate study of the exposure for irregular large-scale radio arrays taking into account most important features of detection, which will be used for the measurement of primary cosmic-ray spectra with Tunka-Rex.

Measurement of cosmic-ray air showers with the Tunka Radio Extension (Tunka-Rex)