Development of FIREBall with Geant4

Measurement of conversion electrons in coincidence with gamma rays is an important aspect of nuclear structure studies. We are building on the current existing Internal Conversion Electron Ball (ICEBall) mini-orange array of SiLi detectors to construct an improved fInternal ConveRsion Electron Ball (fIREBall) array with improved efficiency and performance.  The current array of six mini-orange Si(Li) detectors will be replaced with six new, thicker Si(Li) detectors and the magnet filters will be replaced with new, optimized designs. The magnetic elements are used to create a field that the electrons follow after being produced in nuclear reactions. The goal is to improve the efficiency of collecting the electrons with a redesign of the magnetic elements. Using a combination of FreeCAD, COMSOL, and Geant4, we created an efficient, working simulation to identify magnet shapes that would improve the absolute efficiency. We have completed preliminary experimental tests of the simulations with our new magnet shapes and will proceed onto repeating a previous experiment on ICEBall, a ^152,154Sm(α,2n)^154,156Gd reaction, to determine the improvements achieved, specifically in coincidence measurements. The results from our magnet tests and details about our upcoming run will be presented.