G. Stancari

Francium sources at Laboratori Nazionali di Legnaro: Design and performance

A facility for the production of radioactive francium is operating at the laboratories of the Istituto Nazionale di Fisica Nucleare (INFN) in Legnaro, Italy. The goal is to collect a cold sample of radioactive atoms in a magneto-optical trap for studies in atomic, nuclear, and particle physics. Production of francium is achieved via the fusion-evaporation reaction Au197(O18,kn)215−kFr generated by a ∼100‐MeV O6+18 beam on a thick gold target. The production target is heated to ∼1200K and kept at a potential of +3kV to enhance Fr diffusion and surface desorption. Average production rates are 0.7×106ions∕s for Fr210 with a primary beam flux of 1012particles∕s, with peaks of 2×106ions∕s. Details are given on the design and construction of the production targets and on the measurements that characterize their performance.

The Legnaro francium magneto-optical trap

Laser cooling and trapping of radioactive atoms represent the new frontier in atomic physics and a new powerful tool in nuclear physics. We are setting up at the INFN-Legnaro National Laboratories a laser cooling facility that has as a first goal the realization of a 210Fr magneto-optical trap. The general outline of the experiment and the improvements of the final trap efficiency are discussed. Some preliminary results are presented.

A francium MOT for atomic parity violation measurements

The apparatus for the production and trapping of francium is described and its performances are reported. Latest results on magneto-optical trapping of Francium are summarized: trapping of 209, 210, 211 Francium isotopes, measurements of their trapping frequencies, measurements of diffusion parameters of Francium ions in yttrium. Future experiments on fundamental physics are presented.

Laser cooling and trapping of radioactive atoms

Laser cooling and trapping techniques made possible during the last two decades important achievements in the atomic physics and quantum mechanics fields. These same techniques can be usefully applied to radioactive atoms by opening new fields of investigations. Nuclear processes can be studied with the atomic physics tools. We focused our attention on Francium radioactive atoms. A magneto-optical trap has been set up at the INFN Legnaro laboratories. Preliminary tests with other stable alkali atoms aimed at an improvement of the MOT collection efficiency are reported. Fast and efficient trap loading of rubidium has been obtained through the light-induced atomic desorption from an organic coating. A larger number of sodium atoms, as compared to monochromatic trapping laser, has been trapped by using a broad-band laser.