Summer Student project report: counting antiprotons in ASACUSA's Cusp trap

Antimatter is an elusive part of our universe, but its understanding is crucial to the development of coherent and well functioning theories. It was first discovered in the 20th century, and its existence was predicted by the physicist Paul Dirac. The most common way to obtain antimatter is through β decay, where a proton will decay into a neutron, a positron as well as a neutrino p → n + β + + νe. The positron is the first antimatter particle to be discovered, which occurred in 1932 by Carl Anderson. To make more complex antimatter structures, large machinery is required. In particular, accelerators are necessary. This allows us to collide charged particles with a target, selecting for a precise reaction yielding the desired antimatter. At CERN, this happens in the antimatter factory [1,2], where protons from the Proton Synchroton are collided with an iridium target to produce antiprotons. Once produced, they can be stored and various properties can be studied. In particular, the ASACUSA collaboration is working towards measuring the hyperfine structure of antihydrogen. To do so, it is crucial to have an estimation of how much antimatter was trapped for a given experiment. This leads to the subject of this report, which concerns some of the antimatter detectors in the ASACUSA collaboration. Firstly, antiproton plasma was dumped onto a microchannel plate-phosphor screen (MCP) detector outside the trap, with the emitted light being recorded by two independent silicon photomultiplier (SiPM) systems. The results were analyzed and compared to control for systematic effects in identifying single annihilation events. Secondly, antiprotons were caused to annihilate inside the trap, at a magnetic field minimum. The annihilation signal was recorded by a scintillator bar system, which is connected to photomultimpliers (PMTs). This system also needs to have its efficiency estimated. To do so, simulations were conducted and analyzed. The ultimate goal was to study these reliability of the detectors of the ASACUSA experiment and characterize their behavior to make better estimates of the amount of antiprotons that are being trapped.