Protonated Water Clusters in TPC Detector Yunus KAYA ykaya@uludag.edu.tr Protonated water clusters n = 1-9 n = 1 n =2 n = 3 n = 4 n = 5 n = 6 n = 7 n = 8 n = 9 Water is a dipole molecule, and it consists of large protonated water clusters with proton. These clusters are heavier and hence slower than the primary ions. Therefore, It is important to determine the size distribution of protonated water clusters in atmospheric pressure and room temperature. The shapes of clusters vary depending on the orientation of hydrogen bonding, and so clusters are different symmetry We use Gaussian 09 program and density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set. 13. Pisa Meeting on Advanced Detectors 24-30 May 2015, La Biodola, Isola d'Elba (Italy)

The thermodynamic parameters and the most stable structures were determined for all different cluster sizes. The curves of DHºn-1,n, DGºn-1,n, DSºn-1,n and equilibrium constants Kn-1,n with n was plotted to determine the size of protonated water cluster. Protonated water clusters have at stp a size of 6 to 9, which its mass is ca. 127.1-181.2 gmol-1. Conclusion: Ions in wet gases are larger and slower than in dry gases. This modifies ion-induced signals and may lead to increased space charge in large devices such as TPCs. 13. Pisa Meeting on Advanced Detectors 24-30 May 2015, La Biodola, Isola d'Elba (Italy)