Speaker
Description
Antihydrogen, the bound state of a positron and an antiproton, is a uniquely powerful system for precision tests of fundamental symmetries between matter and antimatter. The ALPHA collaboration synthesises antihydrogen by merging cold positron and antiproton plasmas. The positron temperature limits the number of trapped antihydrogen atoms, thereby constraining the data-taking rate and increasing statistical uncertainties in precision measurements.
We report a major advance using sympathetic cooling of positrons with laser-cooled Be$^+$ ions, reducing temperatures below 10 K, a factor of two colder than with previous methods. When synthesising antihydrogen with this colder positron plasma, the trapping rate increased by an order of magnitude, allowing the accumulation of over 15,000 atoms in under seven hours. Extending this technique to the ALPHA-g apparatus yielded a factor of 20 improvement in antihydrogen production, enabling more precise and efficient measurements of the interaction between gravity and antihydrogen.
This paradigm-shifting technique enhanced precision measurements at ALPHA, such as the 1s-2s transition in antihydrogen, strengthening comparisons with hydrogen and allowing for more sensitive tests of matter-antimatter symmetry.