Cooling antiprotons in an ion trap

The measurement of the inertial mass of the antiproton and proposed antihydrogen formation experiments require antiprotons stored in ion traps, cooled to very low (4K) temperatures. Techniques to cool the trapped antiprotons from energies around 1 keV are discussed. Coupling to an external circuit produces cooling times of order 10³ s, which may be reduced somewhat with negative feedback. Adiabatic reduction of the trapping potential produces significant cooling when the particle energies are substantially less than the well depth. Most promising is cooling via energy-transferring collisions to a cooled cloud of electrons simultaneously trapped with the antiprotons. Electron cooling times are of order 1 s, and strongly depend on electron number and density.     

A193Ir Mössbauer study of Pt−Ir catalysts prepared by impregnantion of silica with H2MCl6

The state of iridium on Pt?Ir catalysts prepared by impregnation of amorphous silica with H₂IrCl₆ and H₂PtCl₆ was studied by¹⁹³Ir Mössbauer spectroscopy after different steps of preparation. The Ir is adsorbed in its trivalent state, presumably as [IrCl₆]^3?. Calcination in air at 450°C converts this to IrO₂. The metallic clusters formed by subsequent reduction in H₂ at 200°C show a strong tendency towards segregation of Ir and Pt and re-oxidize partially when exposed to air at ambient temperature. In both respects the behaviour is similar to that of samples prepared by co-exchange from [Ir(NH₃)₅Cl]Cl₂ and Pt(NH₃)₄Cl₂. H₂O.     

Photoassociation of sodium in a Bose-Einstein condensate

We form ultracold Na2 molecules by single-photon photoassociation of a Bose-Einstein condensate, measuring the photoassociation rate, linewidth, and light shift of the J = 1, v = 135 vibrational level of the A1 Sigma (+)(u) molecular state. The photoassociation rate constant increases linearly with intensity, even where it is predicted that many-body effects might limit the rate. Our observations are in good agreement with a two-body theory having no free parameters.     

Laser manipulation and cooling of (anti)hydrogen

This paper is a summary of a talk presented at the Antihydrogen Workshop in Munich, July 1992. We discuss the possibilities of laser cooling antihydrogen and the compatibility of laser cooling with the experimental environment needed for the production and trapping of antihydrogen. Most envisioned experiments will require or be enhanced by the production of very cold antihydrogen.