Speaker
Description
The ALPHA colaboration has recently demonstrated laser and microwave spectroscopy of several
different transitions in the antihydrogen atom. Since we typically trap around only twenty
antihydrogen atoms per experimental cycle, in these experiments we choose to accumulate hundreds
of antihydrogen atoms over time scales ranging from tens of minutes to many hours in order to have
a sufficient number of antihydrogen atoms for a given measurement. These long experimental runs
limit the number of experiments that can be performed, especially due to our finite allocation of
the antiproton beam.
To increase the rate of data aquisition, and potentially the precision of future spectroscopic
measurements, we are currently working towards increasing the antihydrogen trapping rate. The
positron temperature is thought to play a vital role in both the rate of antihydrogen formation, and
on the trapping rate of antihydrogen. Currently, positrons that we use for antihydrogen synthesis reach a temperature of around 30K. By lowering the positron temperature, significantly more
antihydrogen atoms should be trapped.
We propose sympathetically cooling the positrons using laser cooled beryllium ions, 9Be+, a
technique that has previously been demonstrated. Simulations in ALPHA have shown that the
temperature of the positrons could potentially be reduced to less than 5K if cooling is maintained
during antihydrogen formation. We have recently demonstrated trapping and laser cooling of
beryllium ions, using an ion source which was designed to operate under the significant constraints
imposed by the ALPHA apparatus. We are currently performing experiments where we mix the
laser cooled ions with positrons and will present our latest results towards sympathetic cooling.
