Possibility of Producing Inverted Population in Atomic Beams by Charge Exchange with Atoms

Bailey L. Donnally, Thomas Clapp, William Sawyer +1 more

Mark P. Silverman, F. M. Pipkin

This series of articles will describe a novel method of utilizing optical detection of RF-induced fine structure transitions to investigate the population of excited states of fast hydrogen atoms produced by charge exchange collisions between an initial proton beam and various gas or foil targets. In Part I a model of the charge exchange collision and the interaction of the hydrogen beam with an external oscillatory field are considered within the framework of the density matrix formalism and expressions are obtained for the RF lineshapes in terms of the initial atomic density matrix elements.

R. G. Unanyan

C. H. Storry

Our ATRAP collaboration has now demonstrated a second technique for antihydrogen (H̄) production. Lasers are used for the first time to control the production of H̄ atoms in our cryogenic apparatus at CERN. As suggested in ref. [2] and first reported in ref. [1], lasers excite a thermal beam of cesium (Cs) atoms to a Rydberg state. In a first charge exchange collision one of these laser‐excited Cs atoms (Cs*) and a cold e+ produces positronium (Ps). Our measurements at Harvard([3]) and at CERN([1]) confirm CTMC simulations([2]) that the laser‐selected binding energy in the Cs atom is preserved by the collision and results in Ps with the selected binding energy. A second charge exchange is between one of these Ps atoms and a trapped p̄ . H̄ is produced by this second collision and is expected to again have the same binding energy. One advantage of this technique as discussed in ref. [2] is that the H̄ produced is expected to be extremely cold, at the temperature of the trapped p̄ , allowing for possible confinement of the H̄ atoms in a magnetic trap.

W. Shearer-Izumi

Nafia Rahaman, Russell McLean, Dmitry Budker +1 more

Mid-infrared radiation at 5.23 µm is used to probe the population-inverted 5D 5/2 →6P 3/2 transition in rubidium atoms, key to a widely studied frequency up-conversion scheme that produces coherent blue light. We find that resonant probe light significantly changes the optical properties of the inverted medium, which exhibits high optical gain. The gain has a complex sensitivity to factors such as pump laser detuning, beam alignment, and atomic density. The results are an important step toward characterizing new optical field generation in alkali atoms.