LIFETIME MEASUREMENTS OF RYDBERG STATES USING A SAMPLE OF COLD ATOMS

A. L. Oliveira, R. A.D.S. Zanon, K. M. F. Magalh\~aes and L.G. Marcassa

Instituto de F\'{\i}sica de S\~ao Carlos
Universidade de S\~ao Paulo
Cx. Postal 369 - S\~ao Carlos -SP - Brasil
13.560 - 970

We have carried out lifetime measurements of Rydberg states in a sample
of cold trapped Rb. The Rydberg atoms were detected by pulsed field
ionization technique. Due to the low velocity of the atoms we can
observe the time evolution of the Rydberg population during very long
periods ($\gt 30 \mu $s) for high n (n$\gt 25$). Collisional effects are
also observed.