A point source emitting alpha particles is placed at a distance of 1m from a counter which records any alpha particle falling on its 1 cm 2 window. If the source contains 6.0 × 10 16 active nuclei and the counter records a rate of 50000 counts/second, find the decay constant. Assume that the source emits alpha particles uniformly in all directions and the alpha particles fall nearly normally on the window.

A point source emitting alpha particles is placed at a distance of 1m from a counter which records any alpha particle falling on its 1 cm² window. If the source contains 6.0 × 10¹⁶ active nuclei and the counter records a rate of 50000 counts/second, find the decay constant. Assume that the source emits alpha particles uniformly in all directions and the alpha particles fall nearly normally on the window.

Given, Count received at 1m from source = 50000 counts/cm²sec

As it is a point source, total nuclei radiated from the source

= Counts received per unit area × total area

So,

No. of active nuclei

Now,

∴

1