Gain Mapping of a Micromegas Detector by Localized Beta Emissions

The Texas Active Target detector is a time projection chamber used for Rare Isotope Beam experiments conducted at the Cyclotron Institute at Texas A&M University [1]. A primary component of the TexAT is a micromegas detector, which amplifies and detects electrons resulting from charged particle interactions in the tracking region. This allows for particle track reconstruction, which requires high precision in both energy measurement and position of impact. The micromegas manufacturing process, primarily sheet stretching and curing [2,3] results in mechanical deformities in amplification gap distance. Variations in the gap length exponentially affect the detector response. Therefore, it is important to characterize variations in the gap uniformity. In this work, this uniformity was studied by measuring detector energy response to a localized Sr-90 beta source. The resulting gain map for each detector can then be used to improve the data quality in future experiments.