Atmospheric pressure dependance of HAWC scaler system
Atmospheric pressure dependance of HAWC scaler system
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HAWC 洁牙机系统的大气压力依赖性
DOI：
10.22323/1.358.1095
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
J. Ryan
中科院分区：
文献类型：
--
作者：
Arun Babu Kollamparambil Paul;A. Lara;J. Ryan
大气压力的变化是由于上面的气柱质量的变化，这反过来又类似于大气密度的变化，并将影响宇宙射线的二次粒子的衰变。地面宇宙射线探测器观测到它们的通量随压力的变化。高海拔水切伦科夫（HAWC）伽马射线天文台由于其高海拔、高正常运行时间和大面积（包括总光电阴极面积）是一个伟大的二次粒子探测器，这使得HAWC标度系统成为太阳调制研究的理想仪器。虽然，为了进行这些研究，有必要隔离和消除大气调制。观测到的每一个PMT的速率都具有太阳和大气调制的特征，这使得测量压力系数变得困难（$\beta_P$）。HAWC点的压力表现出周期性的行为（$\sim$ 12小时），这也反映在标量速率上。利用这一周期性特性对压力调制进行了分离，并对$\beta_P$进行了准确估计。由于压力依赖性是一种物理现象，PMT的估计系数应该是相同的，任何偏离都可能是由于PMT的故障。这使得该方法成为识别故障pmt的有用工具，并帮助我们将它们从分析中分离出来。在此分析中，我们提出了压力系数的估计方法，并利用该方法对HAWC标量数据进行校正，使其适合于太阳调制的研究。
The variation in atmospheric pressure is due to changes in mass of the air column above, which in turn resembles the density variation of atmosphere and will affect the decay of secondary particles of cosmic rays. The ground based cosmic ray detectors observe pressure dependent variation in their flux. The High Altitude Water Cherenkov (HAWC) gamma ray observatory is a great detector of secondary particles because of its high altitude, high uptime, and large area (including total photo-cathode area), which makes the HAWC scaler system an ideal instrument for solar modulation studies. Although, in order to perform these studies it is necessary to isolate and remove the atmospheric modulations. The observed rate in each PMT has signatures of both the solar and atmospheric modulations, which makes it difficult to measure the pressure coefficient ($\beta_P$ ). The pressure at the HAWC site shows a periodic behavior ($\sim$ 12 hours), which also reflects in the scalar rates. This periodic property was used to isolate the pressure modulation and $\beta_P$ were estimated with accuracy. Since the pressure dependence is a physical phenomenon, the estimated coefficients for PMTs should be identical, any deviation from this can be due to malfunction of the PMT. This make this method a useful tool to identify the malfunctioning PMTs and help us to isolate them from the analysis. In this analysis we are presenting the method of estimation of the pressure coefficients and its usage to correct the HAWC scalar data to make it suitable for the solar modulations studies.