Temperature dependence of anti-hydrogen production in the ATHENA experiment

Recombination and cascade of Rydberg antihydrogen

“…We address the limitation of the quasi-steady-state (or quasi-static) assumption used in previous studies of CR recombination. Both the ATRAP and ATHENA experiments involve strong magnetic fields on the order of a few Tesla [9,8], and so we must qualify the predictions reported here since our investigation does not include the effects of external static fields. However, proposed next generation experiments [13] will utilize trap configurations in which the physical region, where recombination takes place, is field free.…”

“…In the ATRAP experiment the antimatter plasma is characterized by a common positron-antiproton temperature of about 4 K [9]. Somewhat higher temperatures are reported for the ATHENA experiment [8]. Positron densities on the order of 10 8 cm −3 are typical [9].…”

“…In the ATRAP experiment, three-body recombination [12] has been invoked as the mechanism responsible for the creation of antihydrogen atoms in excited Rydberg states [11]. In the ATHENA experiment three-body recombination as well as radiative recombination is believed to play a role in the synthesis of antihydrogen [6,8].…”

Antiparticle cloud temperatures for antihydrogen experiments

“…As a result, there are few investigations of the temperature dependence of H formation, and the information that exists is somewhat confusing. For instance, by studying several measures of the H yield (as a proxy for the rate of formation [31]) while T e was raised in a range up to several thousand kelvins, ATHENA found a temperature scaling of the rate according to T (−0.7±0.2) e [32,33]. In a later study, using a modulated rf heating technique, Fujiwara and co-workers [34] were able to model the onset of H annihilation following the removal of the rf to yield a formation scaling law as T (−1.1±0.…”