A group of atoms is confined to a very small (point-like) volume in a laser-based atom trap. The incident laser light causes each atom to emit 1.0 x 106 photons of wavelength 780 nm every second. A sensor of area 1.0 cm2 measures the light intensity emanating from the trap to be 1.6 nW when placed 25 cm away from the trapped atoms.
Assuming each atom emits photons with equal probability in all directions, determine the number of trapped atoms.