Computational investigation of the feasibility touse solid neon moderation for GBAR

The main goal of the GBAR (Graviational Behaviour of Antihydrogen at Rest) experiment is to investigatethe gravitational effect on antimatter by measuring the classical free fall of an antihydrogen atom. The requiredpositrons are created by pair production inside a tungsten target and are moderated using a tungsten mesh. In thisthesis, two schemes are examined to determine the feasibility of replacing the tungsten moderator with a solid neonmoderator which would increase the moderation efficiency from η+,W ≈ 10−3 to η+,Ne ≈ 10−2. For the first scheme,the moderator is placed directly behind the target. We determined the power deposition inside the moderator tobe approximately 60 W which is at least one order of magnitude larger than the available cooling power to keep theneon at the required temperature. For the second scheme, a combination of magnetic fields is applied to separatethe electrons from the positrons before hitting the moderator. The field configuration was optimized leading to 11%to 16% of positrons hitting the moderator that have mostly small kinetic energies. Finally, an energy consideringscoring function was developed which values slow positrons higher and the relevant magnetic fields were optimizedwith respect to reaching the maximal score.