A Historical Note about how the Property was Discovered that Hydrogenated Substances Increase the Radioactivity Induced by Neutrons

TL;DR

This paper revisits the historical discovery that hydrogenated substances enhance neutron-induced radioactivity, revealing it occurred two days earlier than previously documented through analysis of original documents and personal recollections.

Contribution

It provides new historical evidence pinpointing the discovery date as October 20, 1934, based on archival research and comparison with personal accounts.

Findings

Discovery date is October 20, 1934, not two days later as previously thought.

Archival documents support earlier discovery date.

Historical analysis emphasizes the importance of cross-referencing sources.

Abstract

At the "Domus Galilaeana" in Pisa, many original documents and records are kept, which belong to the scientific activity carried out by Enrico Fermi until 1938. I compared those documentary sources with the supported evidences, the personal recollections, concerning the discovery that hydrogenated substances increase the radioactivity induced by neutrons: such a comparison leads to the conclusion that the discovery occurred on October 20th 1934, i.e., two days before the date that all the accounts that have been supported so far report. That suggests that any historical study to come, and regarding the experiments carried out by Fermi and his group on neutrons, cannot neglect to analyse carefully the accounts regarding those experiments and to compare them with the archive records.