Lifetimes of n 1P states in helium

We have determined the lifetimes of helium n 1P states, from the shortest 2 1P (560 ± 14 ps), up to the 10 1P (59.8 ± 1.5 ns). The experiment was performed by measuring the time dependence of UV fluorescence after the resonant excitation of states with pulsed synchrotron light. The apparent lifetimes have been extrapolated to the zero gas pressure limit for each n. Cascade decays of the initially prepared states and the effect of periodic target excitation have been also considered. The results are compared with our MCHF calculations and with other theoretical and experimental values.