Study of positive ion backflow in gaseous detectors by computer simulations

• Grant number: 19/14705-2
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): September 01, 2019
• Effective date (End): August 31, 2020
• Field of knowledge: Physical Sciences and Mathematics - Physics - Nuclear Physics
• Principal researcher: Tiago Fiorini da Silva
• Grantee: Raphael Wictky Sallatti
• Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The invention of micropatterned gaseous detectors has triggered a number of researches and developments in a new generation of gaseous detectors. One particular model has attracted much attention from several research groups: the Gaseous Electron Multiplier (GEM). This technology enables the development of unprecedented spatial resolution detectors capable of high rates of events, as well as having large sensitive areas, increased operational stability and increased radiation resistance. However, other aspects still require developments so that the use of the micropatterned gaseous detectors may be suitable for some specifications of these applications. One of them refers to the backflow of ions in the gas. This is a phenomenon that occurs during the operation of gas detectors and refers to the movement of positive charges (ions) in the gas towards the drift region. Because the ions move much slower than the electrons in the gaseous medium, this backflow of ions generates an accumulation of positive electric charges in the drift region. This accumulation changes the distribution of electric fields inside the detector, generating a change in the gain at high event rates. The aim of this project is for the student to make contact and develop skills in the simulation of gaseous detectors, with the objective of studying the accumulation of positive ions in the amplification region.