Sympathetically Cooling Positrons with Laser Cooled Beryllium Ions for Enhanced Antihydrogen Synthesis

Antihydrogen, the antimatter counterpart of hydrogen, is an ideal system for testing fundamental symmetries between matter and antimatter. However, accumulating sufficient antihydrogen for precision measurements is difficult due to challenges with creating antiproton and positron nonneutral plasmas that are cold and dense enough to form trappable antihydrogen when merged. To address this challenge, we now sympathetically cool positrons with Doppler laser cooled beryllium ions before they are merged with antiprotons. The achieved reduction in positron temperatures increased the antihydrogen trapping rate eight-fold, resulting in a daily availability of 10⁴ anti-atoms.



Here we discuss the positron sympathetic cooling technique and its integration into antihydrogen production. An enabling development that will be presented is the extension of the SDREVC technique to laser cooled beryllium ions, where a strong-drive regime rotating wall is simultaneously applied with evaporative cooling. SDREVC stabilizes the ion number and plasma size and allows tuning of these parameters to optimize positron cooling. We show the dependence of the antihydrogen trapping rate on the laser frequency used for beryllium ion cooling, thereby confirming the critical role of positron temperature in antihydrogen formation.