Scaling behavior of the ground-state antihydrogen yield as a function of positron density and temperature from classical-trajectory Monte Carlo simulations

Abstract

Antihydrogen production has reached such a level that precision spectroscopic measurements of its properties are within reach. In particular, the ground-state level population is of central interest for experiments aiming at antihydrogen spectroscopy. The positron density and temperature dependence of the ground-state yield is a result of the interplay between recombination, collisional, and radiative processes. Considering the fact that antihydrogen atoms with the principal quantum number n=15 or lower quickly cascade down to the ground state within 1ms, the number of such states are adopted as a measure of useful antihydrogen atoms. It has been found that the scaling behaviour of the useful antihydrogen yield is different depending on the positron density and positron temperature.

Antihydrogen Synthesis in a Double-Cusp Trap

“…The synthesis ofH does not depend only on the temperature but also on the density of the e + plasma [9]. Figure 5 (a) is the case when a smaller number of e + , 4 × 10 7 , i.e., lower density, were prepared.…”

“…A plasma at lower temperature gives higher yield ofH [9]. It is necessary to mixps with a e + plasma by keeping their relative energy difference as small as possible in order to avoid heating up the plasma.…”

Antihydrogen Formation and Level Population Evolution During Passage Through a Positron Plasma

“…The radiative recombination, spontaneous and stimulated radiative transition rates and black-body radiation calculation is detailed in [1].…”

“…In this work the level population evolution is studied using classical-trajectory Monte Carlo based scattering rate coefficients [1].…”

“…We have used a classical-trajectory Monte Carlo (CTMC) code along with regular atomic codes to generate a scattering database of rate coefficients in various experimentally achievable magnetic field strengths and in low temperature positron plasma conditions. We used these rates to calculate the evolution of level population of antihydrogen during formation, scattering and flight within our experimental conditions [1]. The model and the results are presented.…”