Progress towards an intense beam of positrons created by a Van de Graaff accelerator

Abstract

Abstract A 4MV Van de Graaff accelerator was used to induce the nuclear reaction 12 C(d,n) 13 N in order to produce an intense beam of positrons. The graphite target was heated so the radioactive 13 N would desorb from the bulk into the vacuum. This radioactive gas is frozen onto a cryogenic freezer where it decays to produce an antiparticle beam of positrons. This high current beam is then guided into a superconducting magnet with field strength up to 7 Tesla where the positrons will be stored in a newly designed Micro-Penning-Malmberg trap. Several source geometries have been experimented on and found a maximum antimatter beam with a positron flux of greater than 0.55 ± 0.03 × 10 6 e + s −1 was achieved. This beam was produced using a solid rare gas moderator composed of krypton (Kr) at a temperature of 25 ± 5 K. Due to geometric restrictions on this set up and other loss mechanisms, 10 7 –10 8 e + s −1 of the total number of positrons are lost. Simulations and preliminary experiments suggest a new geometry, currently under testing, will produce a beam of 10 7 e + s −1 or more. The setup and preliminary results for the new geometry will be discussed as well.