Calibration of the Berkeley Gas-filled Separator Through Beam Spot Image Analysis

Super heavy elements (SHEs) are the heaviest elements in the periodic table. They do not naturally exist on Earth and must be created in the lab through complete-fusion neutron-evaporation reactions at particle accelerators. Along with the desired isotope, these collisions primarily produce unwanted reaction products, which must be filtered out. To do this filtering, the SHE research program at Lawrence Berkeley National Lab uses a machine called the Berkeley Gas-filled Separator (BGS). The BGS consists of one quadrupole magnet (Q1), two dipole magnets (M1 and M2), and a vacuum chamber filled with a trace amount, ~0.5 torr, of helium gas. This separates the products of interest from the unwanted reaction products based on different magnetic rigidities in He gas. Each reaction product has its own magnetic rigidity, which is determined by its mass, velocity and the number of electrons that it is missing. The BGS is optimized to send ions of a given magnetic rigidity to a detector. Calibrating the BGS magnets to determine the precise magnetic rigidity for each isotope of interest is a necessary step to take before embarking on the search for the next heaviest element.