Development and Characterization of Parallel-Plate Avalanche Counters for Nuclear Physics Experiments

Sammanfattning: Parallel-plate avalanche counters, PPACs, are commonly used to detect fission fragments. The PPAC detects them and mark (very accurately) the time of detection. Such measurements can be used to measure the neutron energy (via time-of-flight) to study neutron-induced fission.This project report provides a method that, together with the discussed improvements, allows the fabrication of good quality PPAC detectors. Several PPACs are manufactured and the electrodes are built from 0.9 µm thick mylar foils which are evaporated with a 40-80 nm thin layer of aluminum.The developed PPACs are characterized with well known radioactive Cf and Am sources (the source characterization also found in this report), and compared against each other. Additionally, the PPAC signal amplitude spectrum are found to follow theoretical expectations with regards to angular dependence, gas pressure and an applied electrode voltage.At a specific applied electrode voltage and range of gas pressures (3-9 mbar), the measured time resolutions are 2.24-1.38 ns. A trend is observed for finer time resolutions at higher gas pressures.