The Bequerel experiment

I always desired to reproduce some experiments of first pioneers of radioactivity.

Bequerel exposing some photographic plates to the radioactivity of some uranium rocks obtained some foggy image of the radioactive ore. This very simple experiment gived him the “spark” that let him discovery the radioactivity.

How to reproduce it? Simply! I’ve some 4×5″ photographic chassis and some sheet film from Foma czech analog film factory.

The Foma 100ISO film is what I’m using on my large photography analog cameras.

I’ve exposed this film for 24h to the radioactivity of uraninite, autunite and to the alpha rays of an Americium alpha emitter capsule and also added a piece of image intensifying film from an old x-ray casette to a third chassis and I’ve re-done the experiment hoping to see the screen effectiveness in inproving exposure of the sheet film.

Then, I’ve developed and scanned it.

From the left to the right: photographic sheet film, chassis with uraninite, chassis with autunite and Americium

The result confirm at 100% that the radioactivity from autunite and uraninite could expose the sheet film. The image intensify screen confirm it’s efficency too. I must punctualize that I’ve made two errors inserting or extracting sheet film from the chassis because I’ve exposed it to light for about 40% of the surface. Neverthless I’ve obtained nice results. The Americium alpha rays doesn’t reached the sheet film at all, blocked by the 1mm plastic enclosure and the 2mm inner space between chassis “volet” and fim.

Autunite and uraninite without image intensify screen
Uraninite and autunite with image intensify screen.

Author: l.i.papadopol