This was the first time-to-amplitude converter, another of Rossi's contributions to electronic techniques of experimental physics. With absorbers of lead and brass, the number of decays was plotted against time. These decay curves had the same exponential form as those of ordinary radioactive substances, and gave a mean lifetime of 2.3±0.2 microseconds, which was later refined to 2.15±0.07 microseconds. After the war, Rossi discovered that his Italian colleagues, Marcello Conversi and Oreste Piccioni, had performed experiments very similar to his and measured a lifetime consistent with his result.