Studying the transport of positive ions in micro-patterned gaseous detectors of radiation by computer simulations

• Grant number: 22/10779-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2022
• End date: September 30, 2023
• Field of knowledge: Physical Sciences and Mathematics - Physics - Nuclear Physics
• Principal Investigator: Tiago Fiorini da Silva
• Grantee: Natalia Marie Decroix dos Santos
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 20/04867-2 - High energy physics and instrumentation with the LHC-CERN, AP.ESP

Abstract

The invention of micro-patterned 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 micro-patterned gaseous detectors may be suitable for some specifications of these applications. One of them refers to the back-flow of ions in the gas. This is a phenomenon that 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 back-flow 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. Additionally, the ions may accumulate in the insulating walls, affecting the performance. 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 insulating walls.