The High-Altitude Water Cherenkov experiment (HAWC) observatory is located 4100 meters above sea level. HAWC is able to detect secondary particles from extensive air showers (EAS) initiated in the interaction of a primary particle (either a gamma or a charged cosmic ray) with the upper atmosphere. Because an overwhelming majority of EAS events are triggered by cosmic rays, background noise suppression plays an important role in the data analysis process of the HAWC observatory. Currently, HAWC uses cuts on two parameters (whose values depend on the spatial distribution and luminosity of an event) to separate gamma-ray events from background hadronic showers. In this work, a search for additional gamma-hadron separation parameters was conducted to improve the efficiency of the HAWC background suppression technique. The best-performing parameters were integrated to a feed-foward Multilayer Perceptron Neural Network (MLP-NN), along with the traditional parameters. Various iterations of MLP-NN's were trained on Monte Carlo data, and tested on Crab data. Preliminary results show that the addition of new parameters can improve the significance of the point source at high-energies (~ TeV), at the expense of slightly worse performance in conventional low-energy bins (~ GeV). Further work is underway to improve the efficiency of the neural network at low energies.
Detection of Near Horizontal Muons with the HAWC Observatory
HAWC（High Altitude Water Cherenkov）伽马射线天文台能够观测到几乎水平轨道的μ子。HAWC位于海拔4100米a.s.l.在墨西哥内格拉火山上。HAWC探测器由300个水箱组成，每个水箱直径为7.3米，高4.5米，密集分布在22，000米$^{2}$的物理区域内。先前和当前的实验已经在海平面或接近海平面处观测到高天顶角（接近水平）μ子。HAWC作为一个hodoscope能够观察多TeV μ子在天顶角大于75度。这是第一个在高海拔测量近水平μ子的实验，并且多个μ子的距离很大（$\geq$ 10 m）。通过观察以光速传播的近水平粒子，这些μ子可以与广泛的空气簇射区分开来。Sierra Negra和Pico de Orizaba火山的邻近提供了对μ子的额外测量，其岩石覆盖物相当于几公里的水。我们将介绍HAWC观测这些μ子事件的角分布和速率
HierArchical Wavelet Coefficients on the Sphere (HAWCS): the Scattering Transform on Spherical Maps
University of British Columbia（不列颠哥伦比亚大学）；Université Paris-Saclay, CNRS/IN2P3, IJCLab（巴黎萨克雷大学，法国国家科学研究中心/法国国家粒子物理研究所，IJCLab）；Institute of Theoretical Astrophysics, University of Oslo（奥斯陆大学理论天体物理研究所）
An Approach to Gamma-Hadron Separation via Measurements of the Middle-UV Fraction of EAS emission by an Imaging Atmospheric Cherenkov Telescope with UV-Sensitive SiPM detectors
