Spectrum of the LED. The red dotted line indicates the ionization threshold of Rb atoms in the first excited 5P 3/2 state. Inset: Level scheme of 85Rb.
Circuit diagram of the pulsed LED. For explanation see text.
Schematics of the experimental setup. Rb atoms are trapped in a magneto-optical trap in the center of a recoil-ion momentum spectrometer and ionized by the light emitted from the LED, which is imaged onto the atom cloud. The aspherical imaging lens has a focal length f = 40 mm. The ions are accelerated towards the MCP detector by the voltage U E and focused in time by the voltage U F before entering the field free drift region with the voltage U D = 0.
Loading curve of MOT with and without the LED. The data points correspond to the fluorescence signal converted into a total number of trapped atoms. The yellow solid lines are a fit of Eq. (1) . The intensity of the LED are I LED = 190 W/m2 and I LED = 370 W/m2, measured at the position of the atom cloud.
Measurement of temporal intensity distributions of the LED in pulsed mode. The LED is pulsed for 30 ns (blue solid curve) or 100 ns (red dashed curve). After a time of flight of 315 μs the ions are detected and have a time spread of 190 ns (blue open circles) and 300 ns (red solid circles) (FWHM), respectively.
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