Transmutation

I was reading Oliphant et al. (1934) paper, which is freely available online, on transmutation with heavy hydrogen (deuterium), or normal hydrogen with an extra neutron.  They used a discharge tube with 400,000 volts and a brick wall to screen themselves from X-rays.  They used an ammonium chloride solution with heavy water deposited on an iron target and shot deuterium ions at it.  They seemed to be interested in deuterium's effect on other atoms and almost missed the important result, deuterium-deuterium interactions.  At first they just assumed it was a side effect due to X-rays being produced by the high voltage bombardment.  But when they turned the power down the effect was still there and they realized there was a large number of protons being emitted.  They looked around with a Geiger counter and found out a huge amount of radiation was being produced.  It penetrated 20 cm of lead without any reduction in intensity and they realized it was neutrons being emitted and deducted helium was being generated from the hydrogen nuclei and releasing large amounts of energy. 

It is fun to read about how honest they were that they stumbled onto this effect (hydrogen fusion) without expecting it, but they were smart enough to deduce what was actually going on.