The Frontiers of Society, Science and Technology ISSN 2616-7433 Vol. 3, Issue 1: 145-150, DOI: 10.25236/FSST.2021.030123 Published by Francis Academic Press, UK -145- Monte Carlo Based Glauber Model in Pb-Pb Collisions at LHC Jiayi Wang 1, *, Jianling Tang 2 , Chutian Gong 3 1 St.Olaf College, Northfield MN, 55057, USA 2 The Australian National University, Canberra, ACT 2600, Australia 3 The Second High School Attached to Beijing Normal University (International campus) Beijing, 100192, China *Corresponding Author: wang34@stolaf.edu Abstract: Glauber model is a model used to describe heavy ion collision process. In this paper, we describe an implementation of a Monte Carlo based Glauber Model calculation used for the PHOBOS experiment, which simulates the collision of two heavy nuclei. The nucleon distribution in two initial Pb nuclei is parameterized with Woods-Saxon. The energy profile is √  = 5.5and inelastic cross- section area, i.e  = 72mb. Geometric quantities such as impact parameter(b), the participant elliptical and triangular eccentricities ( 2 ,  3 ) are studied and presented graphically and quantitatively in this paper. The results for collisions of Pb-Pb are compared with other Glauber model calculations which agrees with the results from other studies to a great extent. In this simulation, a decline trend of  2 and  3 is observed with increasing Npart. The centralities of peripheral events (40 to 50 percent centrality) are  2 ranging from 0.5 to 0.4 and  3 being roughly 0.3. The ratio of  3 to  2 is roughly 0.5 at Npart=0 and 1 at Npart=416 (a hundred percent centrality), showing the significance of triangular flow of the area of intersection. The model can also be used to predict geometric quantities in the LHC experiments and other collision processes. Keywords: Glauber Model, Monte Carlo, Eccentricity, Heavy ion collision, Pb nuclei 1. Introduction The study of individual particles can be rather complicated, however, the correlation between particles gives a clearer picture of the properties and geometric quantities desired. This paper studies Pb- Pb collisions to get a better understanding of matter in a Quark Gluon Plasma (QGP) state. The corresponding correlation studies measure the geometric quantities, i.e Fourier coefficients representing hydrodynamic flow of charged particles emitted from the QGP. Quark Gluon Plasma is believed to be the initial state of the universe and has also been a condition to free the quarks. Scientists have been using heavy ion collision to create the condition of QGP. In those collisions, both nuclei are accelerated to extremely high energy and collide, freeing the nucleons from the nuclei and lead to a brief QGP state before those nucleons get together and form hadrons, which has also been believed to be the initial state of the universe. This brief QGP state has been a great interest of scientific study. Over years, experiments have found out some interesting correlations between particles being generated through the collision such as the directions in which the particles go. These correlations have a lot to do with the intersection geometry of the collision. Scientists once have thought that the initial geometry only contains elliptical flow. However, it has been recently proved that although elliptical flow is a dominant term of the angular correlation, other shapes are also present in the intersection area such as triangular flow[1]. This makes the study of initial intersection collision area essential. However, it is difficult to observe the colliding area through detectors, thus models have been built to simulate the collision process. Glauber Models usually can be classified to two main types, as presented in ([2]), the first class is called “Optical Glauber” with randomly distributed radial coordinates and smooth density under Fermi density function. The second class referred to as Monte Carlo model is what allows us to run multiple trials to get numerical results. i.e geometric quantities presented in results section. In this paper, we propose that there exists a strong inverse proportionality between the Number of participants of collision and the eccentricities and simulate collision based on Monte Carlo Glauber